Fun fact: Amongst german electical engineers, these are known as "Gleich-riecht-er" (lliterally translates to "he'll smell soon") which is a play on the german word for rectifier, "Gleichrichter"
An "advantage" of the old Selenium rectifiers is that they had a fairly high resistance, with a strong Positive Temperature Coefficient. Which meant that when used in battery chargers they would self regulate the charge current to a safe value. Even when shorted they would just get hot and (usually) not self destruct. I've seen a few old battery chargers where someone had replaced a damaged Selenium rectifier with a modern Silicon rectifier. Which meant that the first time they were shorted, they would blow the fuse (if it had one). A solution is to put a 60W incandescent globe in series with the mains input to provide the missing Positive Temperature Coefficient.
An interesting idea, the 60W lamp, I assume you mean in the transformers primary. I've had luck with halogen headlight globes in the output, more for short/overload protection than battery charging.
@@paulstubbs7678 it's a really old trick for current limiting, literally going back to the vacuum tube era. Not a good idea with switch mode power supplies, but everything else pretty much tolerated or thrived from that usage.
One downside, other than the high voltage drop of the selenium diode was, like electrolytic capacitors, they'd grow leaky just sitting on a shelf. Usually, like the electrolytic, they'd reform under use, but one had to recognize that and allow reformation to occur before final testing of a repaired unit. I did run into an instance of silicon replacement creating problems, lower voltage drop, which was easily enough countered with an NTC thermistor.
Clive, my experience of these is the smell is nearer to swede than rotten eggs. While fault finding on a power station battery charger one night shift, we (three electricians for some reason, so before privatisation) came to a dead end. We sat thinking on a cig break, and one of the guys said " Has someone dropped one?". We all sniffed the air, and as soon as we agreed the smell was swede, the more experienced guy said "It's a selenium rectifier". Job done. Had the team consisted of more polite people, we may have taken a lot longer to find the problem...
Fascinating. I knew of these components, but not how they worked - and certainly not how they failed! The Wikipedia article on them says "During catastrophic failure they produced significant quantities of malodorous and highly toxic fumes that let the repair technician know what the problem was."
They literally were the origin of my ancient smoke emitting diodes joke. And one of the few things that I actually could barely smell. Apparently, some odors aren't carried by the olfactory bulb, but via the trigeminal nerve, typically some of the nastier things get carried that way to the brain.
Early cinema carbon lamps used approximately 70 amps at lowish voltage DC. Usually using a selenium rectifier. I was called a cinema that had lost a show. On entering the foyer I knew exactly what the issue was by that smell. I returned to the car some some diodes. Everyone was really impressed that I could identify the fault without even going into the projection room. Those were the days!!
A while ago I came across a bridge rectifier made of these in a very old 200kV DC power supply. It had hundreds of tiny discs stacked up in cardboard tubes, dozens of the tubes in series, and the whole thing submerged in oil. Despite all signs, the customer didn't believe the rectifiers could have possibly failed, until they opened the tank and were hit by the stench. Several of the cardboard tubes had carbonized, fallen apart, and dumped their discs all over the bottom of the tank. Mouser sold us a lot of microwave oven diodes that day!
There aren't a lot of applications where a 200kV DC supply would ever have been needed. Was it a commercial broadcast radio transmitter? How huge were the condensors and valves?
GE used this system in their VERY early medical LinAcs. Also fairly common (around this sort of voltage) in earlier X-Ray equipment, especially the high energy (high acc. voltage) tube systems used in X-Ray radiotherapy.
@@tactileslut I know electrostatic filters operate from 50kV to 100kV, not sure about 200kV thou. There are no caps or other components after the rectifiers, except the voltage feedback which is a big resistor divider.
I actually have several rectifiers made up of stacked discs in a phenolic tube with brass end plugs, they came in a box of surplus parts I was given, clearly never used; I wonder if they were from a similar arrangement.
Until about a decade or so ago I had a Halfords battery charger that I bought in the 1960s it was a long narrowish box largely filled with an enormous selenium rectifier about a foot long. It was just a half wave rectifier with no smoothing and I am not sure how good it was for a car battery but it worked for 40 years until it erupted in smoke. I still use the leads and croc clips on a solar battery charger so it sort of lives on
Thank you for that OZ, I find it interesting that Halfords were selling shit battery chargers, even back then. As these would clearly do their best to destroy batteries asap, it comes as no surprise that Halfords have always made very good profit out of Battery Sales...
it may have failed due to the rectifier material absorbing atmospheric moisture, some types i've seen 'painted', (mostly high voltage types) , i have a charger bought new in the mid 80s, also spookily halfords branded 😉, and it has a 'contact cooled' selenium rectifier, basically a stack of rectifier plates, no air gap inbetween, and bolted to a metal plate , to dissipate the heat , still works perfectly, at the moment 😉,
i think they fail because of this, plus heat, rather than just 'age', if painted/sealed and run cool, pretty sure they'd last much longer without issues
Selenium rectifiers made their way into consumer electronics as well. Radios and TVs had them. Sometimes you can do a replacement 1:1 with a silicon diode (1N4007), but in other cases you have to add a series resistance to get the voltage within range. This resistor is almost always required when replacing the selenium rectifier in a portable valve radio that runs from both mains and batteries as the valve filaments are DC and have to be within a specific voltage range. They were commonly used in televisions for a while as well, but in those cases, you usually didn't need to add a resistance, or there was already a series resistor (that usually fails) to modify anyway. The US Navy is what really put the end to Selenium over here in the US. In the early 1960s, it was specified that selenium rectifiers were not allowed as silicon rectifiers were far more reliable. I'm sure this trickled through the military requirements over the years. Remember, this was back when it wouldn't be uncommon for a ship to have possibly a few hundred valves in service at a time.
Just guessing: If the voltage had to be as close as 1:1 as possible and have decent current handling, you could throw a few rectifiers in series (and snip their AC terminals). Not as cost effective as a resistor on low currents, but can drop ~2v per package with a bonus heatsink & mounting setup.
@@TinWhisker for sure. People do the diode string trick when switching out a tube rectifier for silicon as well, since a 5Y3 may drop as much as 50-60V, or in general if B+ is too high (higher modern mains voltage, un-ideal transformer etc). Using zener diodes between center tap to ground is a common method. Can drop tons of voltage with a few diodes. In small radio sets, it's not really worth the effort. I've swapped selenium out of small hallicrafters shortwave radio. It actually worked just fine without a dropping resistor, but I added a low value one to get the voltage closer to schematic measurements.
Selenium is indeed photoconductive. Laser printers use a selenium coating on their drums to transiently store a charge from a corona wire. The laser (or LED) exposes the areas not to be printed and those discharge back through the aluminium drum. The unexposed areas hold a charge and pick up toner with it. After depositing the toner, a light exposes the whole width to clear it and the cycle starts again.
Photonicinduction has an old video about a welding machine with selenium rectifiers. As you can imagine, the stacks were absolutely ridiculous in size.
Yep just left a comment about that! I’ve got stacks of these things that either came out of old welders, or new old stock replacements. Some of them must weigh over 20 pounds, about the size of a 3 gallon bucket! I sure as hell don’t want them or have a use for them.
I've got a 1956 P&H 400 amp AC/DC welder...selenium stack in there....plates are many 8-9" square... maybe 60+ of them, big fan blows on them all the time machines is on....machine still works as well as most modern ones...I can do the 'Aluminum' can or 'Razor' blade welds just fine. it goes down to 3 amps....
Selenium was also used in the first solar panels, installed on a rooftop in New York, in the 1880's. Just like the diodes and other components, the selenium was later replaced by silicon in the panels. Of course the one thing, the film Evolution taught us, is there is also selenium in popular dandruff shampoos.
Those were ZnSe based cells IIRC. Selenium is used these days in CIGS (Copper Indium Gallium Selenide) solar cells, which were a big thing years ago as they were at the time cheaper than silicon cells, but their use has died out in most COTS PV modules as silicon prices cratered in the late 2000s and 2010s.
Rotten Eggs smell is usually code name for the smell of various Sulfur compunds. Selenium (34) is the element just below Sulfur (16) in the periodic table and if remember the "Things I Won't Work With" blog correctly the smell is similar but gets MUCH worse as you move down in the that column, so it would make sense that Selenium diode failures could result in the kind of smell you describe.
@@tonywalton1464 Hey, I used a sulphide shampoo for my dandruff back in the day as well. Turned out I actually just had a really sensitive scalp and that shampoo took me all the way from lots of dandruff to bleeding sores, so I suffered the smell and then kept on suffering!
Eggs? Even rotten? Not even close, more like severely rotten garlic with hints of cabbage. It soaks into the walls, and stays there for years. My grandpa's workshop still has hints of that smell, 25 years after the failure. The element itself isn't too terrible to handle, "trollurium" is much worse 😸
@@CuriousFocker Was told this about tellurium by my chemistry teacher in the first year at secondary school. Apparently it affected the breath of the miners too.
Its actually give me nice idea... what about adding "smell" to electronic components so we know what break down? Like adding strawberry flavor to Capacitor, so when it blew up we will know to replace it? And make it in form of small blob that react only when heat is applied so it "release" smell only when specific temperature is reached that normally pop up capacitor. And the same thing for diodes or resistors... It could actually work...
I really like this idea. You could assign smells to each of the digits in the value of the the component, so combined smells would allow you to identify the value of component that had just failed. ‘Mint chocolate rasberry? Well that’s a bad 1k ohm resistor’, you would say.
@@drakefallentine8351 Yes, components already stink in their own ways when they fail. When a cap sharts itself, the smell is a dead giveaway. If you've ever "smelled semiconductor" when a transistor or diode failed; you know the smell of burning silicon - which is readily distinguishable from burning PCB / resistor etc... These smells are faint however, at least when compared to selenium rectifiers - I'd hate to have my house stink out when a diode in the TV fails!
Um, some types of capacitor (paper based X2 class interference suppression types for example) already will give off a distinctive foul smell (good enough to clear a room…)!
I have an old car battery charger with a selenium rectifier inside. I don't have a car so was going to sell it on eBay. After watching this video, i definitely need to replace the selenium rectifier with a moden silicon one before selling it. I wouldn't want it to fail with that horrible smoke.
@mikeselectricstuff you are correct, the fins are heatsinks, the selenium discs are in the middle being compressed by the bolt, i've taken a couple apart before.. I have a selenium rectifier that is about 3" square, most of it is thin aluminium plates, the discs are about 3/4", the middle terminal is between 2 of the discs with no plate, it came from a car battery charger, of about 10 amps, notably the charger had plenty of vent holes
@@simontay4851 depends upon the condition... If it was in good condition i'd personally buy it only because it was original... But sometimes you can't be 100% original, capacitors are a perfect example.
@@simontay4851 I don't know where i heard it (many years ago), but one reason for using selenium was 'because' of the volt drop, many people turn on the charger before connecting it, then touch the clips togehter, or they connect to a very flat battery, from what i was told, th selenium rectifier could take a quick overload, i think modern chargers with silicon also have an inductor in series. i may be wrong on this.
I’ve changed a lot of these. Back in the day replaced them using the BY100 ‘top hat’ silicon diode which was the forerunner of the 1N4007. Record players and tape recorders often used the small aluminium cased contact cooled selenium rectifiers by Siemens, Westinghouse or STC. The smell wasn’t great when they failed but there’s an industrial two part underwater epoxy that when mixed smells like dog **** and seems to stay with you long after you’ve finished using it - give me the selenium smell any day!!
I've never smelled one burning up, but as an electronics buff kid in the 70s I took apart a few old discarded things that used them. My character of a Grandpa who worked on electronics since the 30s was very vocal about what a selenium rectifier smelled like when it burned up- *a dirty fart!* He also called them rectum-fryers.
@@kaitlyn__L It really does. They have one for FIAT (the car manufacturer) and they have an acronym which from it which basically means "problems in every part" very cunning linguists. Edit: It's "Fehler In Allen Teilen"
PSA for those who wanna experiment with those individual plates: the coating (of the semiconductor, i'm not thinking of the paint) contains cadmium, which is really quite bad. Use gloves when you try and fool around with it, and avoid any sanding/scratching of the surface layers!
@@dougankrum3328 Old soldering wire was really something great, but I'm glad they've mostly done away with it. With modern lead and cadmium free solder you'll be fine as long as you've got good Flux
Clive speculated on the use of the fifth diode in the stack. When choke input filters were used, the choke means that current flows continually, so a fifth diode shunted the bridge rectifier, to provide a path for this current when the bridge diodes turn off. Without this extra diode, circuit operation is a lot less efficient and the heat dissipated in the bridge diodes is a lot higher as the choke will try to force the diodes to stay on. If the filter has an input capacitor before the choke, the fifth diode isn't needed and was not included.
I did something similar: Electric arc with a 7kV 50mA F/ART neon transformer heating ammonium bicarbonate.The entire room and the kitchen next to it had the nice smell.
When I first started my electronics hobby in the 60's, I used selenium rectifiers for 150V and 250VDC power supplies, for valve based radios. Don't remember them stinking, but then I never had a new one. Still, memories can be fun. Thanks.
They release acrid smoke when they catastrophically fail until all of the doping is burned away. If you had working selenium rectifiers or long dead rectifiers, they wouldn't smell.
They don't stink when new unless you short something out that puts too much current through them. They stink a filter capacitor in a radio failed and the rectifier blew.
I did four years as a navy engineer and our older ships (built in the mid-1960s), and even some of the older individual systems on our newer ships, have all sorts of these rectifiers scattered throughout the various control circuits. I never actually knew what they did before now, and always just assumed they were some sort of heat sink around some sort of fusible link. Thanks for sharing!
Great Video! I own a private telephone branch exchange made in 1963. It has one of those rectifiers which still works! It’s all huge relays and capacitors, no semiconductor at all! I can take some pictures for you if you like. Yes, those rectifiers are photo sensitive. They used to make selenium light meters for cameras. A lot of cheaper Super-8 cameras had them until the early 1980s. There was a little meter inside the viewfinder or on top of the camera body and you had to keep the pointer inside a rectangle in the center by adjusting the aperture. There were not linear at all, but all that mattered was to keep the pointer inside the rectangle. The smell of them is really bad. In Germany, we like to call them “Gleich-riecht-er”. A rectifier is “Gleichrichter” (Gleich = same, Richtung = direction, so the word literally means “Same direction worker/contraption”). A small change in letters and pronunciation turns it into “It’s about to reek” (Gleich = soon, riecht = smells, er = he/it). The major downside of them is that they always have a great leak current. The leak current actually helps them to operate in a stack and distribute the voltage evenly. If you want to stack diodes, you need to add resistors in parallel to each or some diodes get much more voltage than others and fail. The selenium rectifiers have those resistors built right in. When the leak turns worse (with aging), they heat up until they fail. In the TV series “Mission impossible” (1966), there is an episode (24, “The Train”) where they simulate a train journey inside a hangar with a train car sitting on pistons and a complex system of tapes and amplifiers creating the sounds. Barney, (the engineer) is sitting in front of his consoles when smoke starts to come out from under his seat. He instantly tells his boss that there is a rectifier is going to fail soon but he can hot-swap it without interrupting the simulation. And then you see him doing it using a spare and jumper wires. www.imdb.com/title/tt0649356/ I like this TV series. Almost all the technical stuff which was next to impossible back in the days can be easily replicated by any good maker nowadays. They remote controlled a truck (like the Mythbusters), used a remote controlled drone, they even used some kind of RFID in a poker tablecloth.
It's funny you mention pinsetters, I've had to replace many of these in my Brunswick A2 pinsetters dating all the way back to 1956. I'm pretty sure I still have one or two original rectifiers, they are absolutely massive in size. When they go out, everyone in the building knows about it, they're that stinky. For some reason I'm still able to buy them new via my supplier, but I always choose to get silicon rectifiers cheap via Mouser. Another funny note, is that Otis Elevator company manufactured the Model A pinsetter for Brunswick for the first few years!
Normally, when someone tells me something like, this smells completely awful, I take that with a grain of salt and move on. When Clive says it, I have absolutely no desire to be in a one kilometer radius of the failed part.
sparkplug1018 I promise you, Oh..boy... they do pong. It's very much like H2S, maybe it IS hydrogen sulphide.. Unquestionably...bad eggs or last night's vindaloo! Embarrassing if somebody who doesn't know about them walks into your workshop!
When I was a kid I got a selenium rectifier from my grandfathers junk box and took it apart and made several solar cells from the plates. The rectifier was similar to the gray one you have but the plates were larger.
Not to mention he doesn't even really edit the videos, they're just a single take or series of single takes appended together, yet he's good enough that you don't necessarily realize it right away.
Never ever begs for likes or subscribes or hitting that stupid bell. He just does his thing. It's the only channel I can think of that is 100% content and zero percent fluff.
On a large DC motor in 1972, I swapped out the selinium field rectifier for a modern one. 6 weeks later the field winding burned out. I had forgotten about the voltage drop in the selinium rectifier.
We had several old battery chargers many moons ago when I was an apprentice at the railways that had them (you literally used a forklift to move them!!!) and know that smell.... Yeah there was no way in hell you would be hanging around when one blew... An open septic tank on a hot summers day with a day old dead cow in it is positively roselike in comparison... They are RANK!!!!
Things to be nostalgic about, eh. Dead cow in a well was pretty bad for me. Things leg tore off while trying to pull it out with a chain block on the bucket of the owners tractor. The smell was horrific and the sight more so. Who's up for a game of fishing? In comparison, I always loved the smell of my grandfathers radio room. It had some interesting smell about it that his wife hated the smell of. I know that he also repaired electrical equipment for a number of services. So I've seen some of these things on his shelves and never knew what they were exactly. Some small and others huge. But they all had a funny smell about them. It's my preferred nostalgic memory. I will however, never be able to get the mental image of "an open septic thank on a hot summers day with a day old dead cow in it" Out of my head. Why does my mind picture someone drinking a margarita while sorting that problem out, whilst pitying the bloke swapping out burnt selenium diode rectifiers, I must be a real oddball, I guess.
I started playing with electronics in the '50's and these rectifiers were used in lots of radios and TV's. Just thinking about them brings that rotten egg smell to mind. There was no doubt when one failed.
Me too. Don't recall any of those rectifiers going bad, though (as opposed to old electrolytic capacitors). We used to call them "Philco Junk Sets". Probably be worth a pretty penny today.
Brunswick pinsetters came equipped with those, to convert power to DC for an electric clutch. You could smell them from 10 lanes away when one burned out. We now have the newer style bridge rectifiers installed on them.
I've had the mispleasure of replacing a few blown ones on my pinsetters, usually the older ones smell worse. I love the new silicon rectifiers, they work great.
Another great informative video Clive. Being an old geezer, these selenium rectifiers were state of the art when I was a youngster. A favourite use was in car battery chargers. Whether or not they had some current regulating characteristics I don't know but very often there was no additional current limiting in the charger and the forward voltage of the rectifier and presumably it's fins which made a good heatsink was all there was. If the selenium rectifier was replaced with a silicon one years down the line, it was necessary to add an high power resistor of a few ohms to limit the charging current in line with your comments. I have a selenium rectifier in a mechanical industrial clock from the fifties an it's still working, but I've put a mains tungsten lamp in series with it just in case it goes short circuit.
I've got a 40+ year old car battery charger with selenium rectifier, used when I got it...4 amps, works great....and I also have a 400 Amp 1956 P&H AC/DC arc welder with a very large stack of selenium ....it works about as well as most of the new welders.
Using a ballast resistor in series is a good idea, as Clive mentions, when converting a selenium stack or vacuum tube rectifier to solid state. I sorted out a Collins 51-J3 receiver where the previous owner replaced the pear-shaped old style 5U4 rectifier with a solid state module, but no ballast resistor was added. The increase in B+ was apparently more stress than the PTO oscillator could handle without permanently throwing the linearity off - that was despite having an 0B2 regulator tube right on the frame of the oscillator can. Sometimes a little thought before execution would be a good thing.
I had no idea this type of rectifier existed but I absolutely love learning about this tech! I've just started my "career in retirement," as it were. I did my first project with 110 AC last week. In unrelated news, I've just had my first regulator release its magic smoke. I wonder what caused that? ;)
I managed to get a brushless motor in one of our laboratory robot arms to burn out at least some of its windings because of an incorrectly placed reagent cartridge that it tepidly poked against. I got weird looks when I opened the cover and exclaimed "I smell magic smoke, that can't be good..."
What a blast from the past, a a babyboomer I remember playing with Selenium rectifiers as a kid. I don't remember the specific smell when they let out the magic smoke but it was pretty strong. Only much later did I learn about the harmful effects. Given how nasty they are I'm surprised they are still available as replacements.
I only came across these a few times. One in an old elevator circuit. I was not allowed to touch this circuit as elevators are covered by another qualification with insurance applied. The other was in old control circuits in the steel mill I was working at for 10 years. They were replaced before failure even though they were very reliable.
If you cut one open, there is literally selenium rectifier confetti inside - tens or hundreds of thin sheet meal discs with a selenium dot in the middle that are the individual diodes, and a spring to push them together. At least that's what's in the Russian ones.
Krzysztof Czarnecki I've got three Russian ones myself. TV 13-03. 13KV rated. I've come across ones like Clive has and also small seleniums for higher voltage yet really low current.
I know that smell very well indeed! The company I worked for used to manufacture battery charging equipment. They also wound their own transformers and assembled Selenium rectifiers. The rectifier test department was definitely an area best avoided!
No, it does NOT smell like a fart, it's MUCH worse...! When I was a kid, I put a little plastic box with a switch in the middle of an extension cord. The middle position of the switch was off, one side would directly connect things, and the other side would put a small selenium rectifier in line. Plug a lamp in and you had a sort of a dimmer. I was showing off this device to a neighbor lady after I'd gotten it built, and then progressed to trying various things out when it let that nasty smoke out. I'll never forget that smell. Much more recently, a friend brought over a nice Grundig tube-based console stereo that he wanted me to fix because he liked the sound of it. I traced the problem to a bad rectifier, and was surprised to find that it was selenium. I put a terminal strip in there and some 1N4007 diodes, and it worked just fine after that. Finding a similar rectifier in my box of diodes, that one went right into the trash. I have a couple of other ones around salvaged from something or other, painted blue. I remember these being in electronics stores I'd go into as a kid and being rated at "500mA". I've absolutely no intension of using them in anything, I just kept them because they look cool... :-) You'd typically see a pair of these along with a pair of electrolytic capacitors in a voltage doubler circuit in some transformerless B&W TVs.
I was also a TV engineer in the late 60's and 70's, and they used them as the mains rectifier with a 200V DC bus on the valve TVs, absolutely dangerous if you touched the live bus, we use to replace them with a BY127 rectifier if my brain is correct, also you had to make sure the bus was discharged before sticking your fingers in.
Thank you Clive, that brought back unpleasant memories from fifty years ago. My first permanent job in 1969 was reconditioning IBM keypunches and verifiers. The older machines used selenium rectifiers in the power supplies for the valves and relays. I was surprised by the stink the first time one failed in our large workshop. I doubt anyone's farts smell as bad! Imagine how bad it would be in a WWII aircraft. Voltage drop was a problem in 1950s DC power supplies. E.G. Both my '00 Gauge' railway and my brothers ''Scalextric' required 12V but the transformer needed to supply 16V RMS. I would often trick my brother into leaving the track by cutting power to my car as he was approaching a corner! Adding a large capacitor to the DC output resulted in faster cars and little variation in voltage with load.
Yeah, 1969...for me it was the Telegraph Machines...the 'new' ones had electronics, transistors and still operated on 48 volts to work with the rest of the copper lines (that are still 48 volts). The teletypes used 120 VAC input, power supply converted to 48 Volts DC. They still needed 120 VAC as there were induction motors driving the printer and tape/keyboard decoder...all that was mechanical.....lots of tiny parts...100's of springs...
This helped me troubleshoot and fix a 1950's Lincoln Fleetwelder 200 arc welder with a non-functioning Arc Strike Circuit. Replaced with an ECG 400V, 40A PRV bridge rectifier - thanks!
I would describe the smell as a combination of sulfur/rotten eggs + garlic + an acrid burning resistor + bloated skunk critter on the side of the road.
The Dynaco stereo system my father built from a kit ("Dynakit"!) in the early or mid 1960s used a selenium stack rectifier in one critical circuit instead of a "normal" vacuum tube. I feel certain I read in the manual they used it for its lower noise, though now I cannot recall if it was in the preamplifier or the FM tuner component. I do clearly remember the rectifier was painted green. 😀
Probably the PAS-3 preamp. Used a selenium bridge in the filament circuit to run some of the tube filaments (probably the phono preamp) on DC to reduce hum.
Brings back memories, thanks Clive. In the 70s and 80s my Dad had a small yacht with an Ailsa Craig outboard motor with built in generator. In the transom was a car battery fed by a blue painted Selenium rectifier having about 4 or 5 plates. This is how navigation lights were run before silicon diodes and solar panels!!
Thanks for sharing this! I’ve troubleshooted an electric panel for a russian big lathe with several selenium diodes. I did not meet anyone who had that experience before. Big hello from Brazil all the best.
5:10 the extra diode would probably be the ground connection for the bridge, making the other negative output be available to supply a negative bias to whatever. This 'backbias' circuit was often supplied by feeding the bridge to ground via a suitable value resistor but in this case they've used a diode, possibly for a more constant voltage drop. And yeah, the pong these things produced when overloaded was horrific.
Hi Clive, I recall in the '60's ., I often used to check the selenium rectifiers of the Ecko TV's with a series lamp of around 60 watts. If they were faulty it was easily detected and often they would arc and produce wonderful "farts"". Yes I am an old fart too!. Love your posts and please keep them up! Cheers, Roger.
When these failed on a TV( very long time ago) we'd bung a BY127 in, dead bug style, and the customer had to put up with the smell till it died away. When tripplers went on TV's (selenium stick rectifiers), we used to tie the faulty ones for return to stores, to the back bumper of the van, so the stench was outside the cab. You wouldn't believe the number of people who asked if it was a speed trap radar jamming device of some type!
Back in the 1960's I was working as an apprentice Radio & TV engineer and these were quite common on older TV sets, when they failed we left them in place and connected a diode to one end with a wirewound heavy-duty porcelain type resistor in series then removed the other lead from the end of the failed rectifier and connected it to the wire wound resistor. The old rec was just left in place to support the diode and resistor.
This video brought back a stinky memory! I was in a college electronics class in 1971 and one of the students was doing a lab assignment. There was a question in the book asking what would happen if a capacitor shorted and the idiot shorted out the circuit to see what would happen instead of just thinking about it. I was across the room when I heard a loud pop and smelled one of the worse smells ever! He had shorted a power supply that used a Selenium Rectifier.
That's the reason why they were called "stink stacks" - that acrid smell. I have a bridge rectifier that looks much like a selenium rectifier, but it has copper oxide on the plates. 🤔👍🤗
Dear Clive, every time I tunein, you're dissecting an old nemesis of mine, this, the rectifier from a 1964 Triump Tiger 650 twin. Big old rectifier about an inch and a quarter square, two tall, on an aluminum heat sink wasting the "excess power" generated by the Lucifer electrics, or more commonly known, Lucas, which seldom have sufficient, much less "excess electric power". On the other hand, components always dump voltage and heat regardless whether it's beneficial, or detrimental. You always bring back warm memories from my youth, back in the late sixties, early seventies. You can run that engine without a battery, rectifier, anything, enough to run the points, engine, straight on the ac generated, barely. Got over a hundred miles that way back about 76. Thanks, always a pleasure!!
It's amazing how many A2's are still in use. I'm currently working on an interface for them to utilize an open-source scoring and league tracking program. Would love to get in touch for technical advice.
The very first electronics repair I ever did, as a lad of 11 or 12, was replacing the selenium rectifier and filter cap in my dad's Sarkes Tarzian table radio, which makes sense since the company that made the radio was a big manufacturer of selenium rectifiers. Named for the Armenian immigrant who founded the company, and an extremely important company in the history of radio and especially television---- they were at the forefront of TV camera and video electronics, and owned a network of broadcast studios. Look up the history of the man and his company, it is a long and fascinating story.
Interesting, I built a small radio from instructions in Electronics Illustrated in 1959 or so, it used a modern silicon rectifier...Sarkes Tarzian...for 60+ years now, I always wondered where that name came from....very interesting, because I'd already read a lot about Nikola Tesla.
The YT algorithm dropped this and I thought WTF for. Didn’t understand a thing but ended up watching the whole thing with interest. Guess the algorithm knows me better than I thought.
I find it interesting that both Sulfur and Selenium form smelly compounds and are both in the Oxygen family of elements in the periodic table. Their outer shells have the same number of electrons and exhibit similar Chemistry. Maybe these similarities cause them both to react with the odor receptors in our noses in the same way?
I would guess that it's to do with the common ion sizes of oxygen being smaller, the bulk of atoms infleunce their reactivity and shape of the molecules it forms.
I have two orange ones I've had since I was a kid. My dad got them from Bell Aerospace where he was project manager on the Agena rocket engines (Saturn and Apolla rockets). My dad passed away last September, but I recently ran across those two diodes. Thanks for the explanation and differences between selenium and silicon!
Thanks for the interesting video. It brought back memories from my days doing maintenance on 3 kw Telefunken FM transmitters in the 70's. The output amplifier ran at around 3.5 kv and cathode current was around 1.2 amps. The 3ph rectifier was made up of multiple banks of selenium stacks.
I don’t know why but “Went the way of things that go out of fashion. It went out of fashion” is just really pleasing to me for some reason. I love non-silicon semiconductors. You can tell the ways they led to silicon’s eventual dominance. But they’re also very interesting unto themselves. I also like seeing older sci-fi which assumed we’d still be using germanium and selenium and so forth hundreds of years from now. Which makes me think about how 2D material research is only just in its infancy with graphene. And how we’re finding various doped semiconductors are just as useful if not more useful than pure carbon in the same kind of lattice for certain uses. You have to imagine they’ll find many more such uses in the next few centuries, with more and more specific formulations. So modern sci-fi which says the computers are graphene… might sound as silly in the future as the earlier example I gave!
You've got to blow one up on camera and inhale the fumes whilst giving us a live report! Do put at least two or three cameras onto the subject of destruction just in case of awesomeness ensuing 😁😁😁
That's one of these times where I WISH we would have Smell-o-vision. I remember the videos of clive blowing stuff up and tearing down big stuff - Now I slightly wish I could experience him letting out the magic horrible smoke, we both nearly choke, have a laugh and then go and have a pint. I really love the videos and I always have the urge to pop on ebay and buy random stuff to just tinker with it.
Went bang and stank the whole room out. I can imagine everyone running away while coughing and gagging either thinking someone just shit themselves or the rectifier failed. I just noticed Clive you don't have a three phase full bridge rectifier with the four that you talked about which I'm guessing is an entirely different type if rectifier compared to the ones you talked about.
You need to watch the latest Great Scott video, he just uses the German word for a three phase full bridge rectifier (literally a six-pole full bridge rectifier, sechspull-something)
Thanks! I've known about these for 30 years but never knew why they looked like that! My first bike, a Honda CL175 had one under the seat. It was probably the only part of that bike I didn't replace, mess with or bother to learn about, as it always charged fine. I recently restored a CB175 for a friend and seeing that bright orange selenium rectifier under the seat brought me back!
Model railroad transformers up until the 1970's or so also used selenium rectifiers. I recall the transformers would give off a slight, odd smell when hot.
Selenium: "I stink. I'll give you garlic breath, metal mouth taste, awful BO and bleeding." Also Selenium: "You must eat me or suffer selenium deficiency and ultimately die." 🤷♂️
Or, as some of us might call them, Satan's fart packs! Usually, if replacing a selenium rectifier with silicon in say, an audio amp, or vintage radio/TV, it's customary to insert a resistor in series to compensate for the difference in voltage drop between silicon and selenium.
I am 73 years old, but I never needed to replace a selenium rectifier. The closest I came to that situation is changing a 6H6 with a transistor. My cousin had an old Rogers Majestic multi-band radio, from about 1937-8. Ron told me that the radio didn't work and asked me to look at it. I had doubts about it but I found the 6H6 had an open filament. He had no money, I had about the same, so I worried about it and decided to replace the 6H6 with a silicon transistor that I happened to have. The radio worked until he died 45 years later.
Always watch your vids, never leave a comment telling you how interesting and enlightening your content is, and how much you absolutely deserve to be on the front page of TH-cam. THAT CHANGES TODAY.
Get a case of White Castle sliders go to the bar eat them along with the pickled eggs and a few beers and the next morning you can clear out the office ! We used to do that to dispatch when we got forced to work Saturday !!
i was eating at a burger joint a long time ago, and the little girl in the corner with her family say " ewwww smells like egg " 30 seconds later i can confirm the fart smelled like egg
I’ve replaced so many of those damned things, and dread it every time! You’d be surprised how common they are, in industrial and precision test equipment. I get a them sporadicly every few months… From a wide variation of clients and equipment. Finding a substitution, can be difficult if it’s damaged or has no identifying marks. And in many cases, it’s in a device that’s either really rare, or so old there’s no available documentation/pictures. Damn hard to find a substitute, if you can’t identify the original or characterize it in anyway. Can be a real bitch. Especially if you’re an idiot… like myself🤪😁
If it's in such old devices I wonder if those companies owning the equipment got rid of the service manuals at some point. Depends a bit on the market segment but I remember a lot of old equipment coming with useful diagrams and specifications, unlikely to see that today for most stuff as an end user.
One blew up in Radio Shop in my High School (1969). It smelled like a combination of rotten eggs and rotten garlic. Not too surprising since its chemical properties are halfway between those of sulfur and tellurium (compounds of which reek of garlic), and selenium is between those elements in the Periodic Table. And yes, if I ever find one in a piece of gear I immediately replace it with an equivalent silicon device plus an appropriate resistor as required.
One site I used to look after (in the 1990's) had a 2kW AM transmitter from the 1950's used as an emergency backup. It originally used Mercury Rectifier tubes. There were two of these in the spares. When they were difficult to get, they attached Selenium rectifier stacks onto the tube bases. There were two of these in spares. When selenium rectifiers became difficult to get, they soldered silicon diodes onto the tube bases. THere were two of these in the spare parts as well. There was about 50 years of history on the shelf just in these rectifiers. The transmitter was replaced in the early 2000's and I don't know where all this history ended up. Sorry to necro-post, but TH-cam just suggested this video today.
I worked in an old mill that used them. The winding machines used 90 volt DC magnetic clutches. The selenium rectifiers used were about 2 feet long and 6 inches square. I asked where they go them and was told they came from a B-17 from WW2. This was in the 80's. They had modern digital timers running the clutches relays and the old selenium rectifiers to get the DC power. It was a real crazy rig up.
These were common in old 405 line Television sets. When I was young, I disassembled many of these old sets, to extract the components. Being about eight years old at the time, there were very few components I knew how to use. The big line transformers the wax paper and big aluminium tin capacitors, and the focusing ring magnets. Later, at around 12 years old, I converted a few TVs to primitive oscilloscopes, using the audio amp to provide Y deflection and the frame amp to give a low speed X deflection time base. . Old TV sets had a range of distinct smells, ranging from burning dust on the valve tops, scorched paxolin pcb resin, the result of the valve heaters, smouldering carbon from underrated potentiometers, to ozone from the EHT, but the smell of burning selenium rectifier, is one, that once smelt, never to be forgotten. Selenium is toxic, though it is reputed to be in some anti-dandruff products. Chemists who work with its compounds can absorb it through the skin and develope very unpleasant body odour and garlic breath as a result.
When I was a kid back in the late 60s, I had a Matchbox-branded slot car racing toy that looked like a kind of cheap-and-nasty Scalextric setup, but instead of applying power to a pair of tracks, with pickup brushes under the cars, this toy had one central motor that drove a long spring around the track, and the cars had a plastic pin underneath that engaged with the spring, thus making the whole thin much cheaper as the cars didn't have to include a motor, and the system would work with any of the Matchbox toy car range. Anyway, it eventually broke down and was duly dismantled, and the power supply for it (around 6V DC if I remember correctly) consisted on just a basic transformer and a selenium rectifier (no capacitor of course as it was just driving a small DC motor) Since other products available at the time were already including silicon rectifiers, I get the impression that either the toy was already outdated when I had it, or the manufacturer just had a stock of ancient components that they wanted to use up
I swear you are the only person that can make a rectifier entertaining & everything else for that matter. One minute you are stabbing a lithium battery or playing with mini chainsaws then next your diagnosing a component on a pcb or carbonating a beverage. By far the best subscription I ever made.
I was recently converting an AC garden light power supply to DC, managed to mix up the pins on the bridge rectifier and as soon as I plugged it in the smoke escaped. That was a silicone rectifier and it smelled bad enough. I can only imagine how bad a selenium rectifier would be. BTW: I remember seeing selenium rectifiers in the old radios I played around with in my youth and they were common on motorcycles until at least the early '70s.
Nice to see your Dual Full-wave Bridge Selenium Rectifier, looks like it was configured for a specific application. Long ago, while going for my EE Degree, I worked as a Test Supervisor at a nearby General Instrument / Radio Receptor Factory. They manufactured Selenium Rectifiers of all types and sizes. Most were dipped in Green paint. When they failed, I kind of liked the smell, more metallic than malodorous. Maybe I just got used to that smell, which has not killed me yet. Failed Electrolytic Capacitors smelled much worse to me. For those seeking the smell specified in the title of this video, try smelling a bottle of the "health" supplement NAC.
I came across this during my apprenticeship as a radio and tv technician. The German name for rectifier is “Gleichrichter” but the nickname for this type was “Gleich riecht er” which means it soon starts smelling. Yes and the smell is like rotten eggs.
When I was an apprentice with the Post Office back in the early 1970s I spent some time in the local repeater station. This was on the ground floor of an 11 storey building. A selenium rectifier fire in a Signalling Unit 18B (a 500Hz/20Hz ringer for private circuits) permeated through the entire 11 floors within a few hours of the event. It lingered in the repeater station for many weeks. Once experienced, never forgotten! Some interesting facts here sbout these rectifiers, especially regarding use in bzttery chargers. I have some relatively recent chargers ( manufacturerd in the past 40years or so) that still used selenium rectifiers. Now I know why!
You are 100% correct on the odor they give off when they blow. Horrible smell that will clear your nasal passages!! And if you think a bad cold will save you, you are sadly mistaken as you will taste it instead. Once you smell it you will never forget it.
About a hundred years ago I repaired teletype machines. Some of the machines in our inventory were Kleinschmidt models 20 and 25 and they had selenium rectifiers in their power supply. Smelling like a fart doesn't begin to describe the odor these things produce when they burn out. At worse its more like burning flesh. The only time I experienced this odorous treat I would have gladly preferred a fart smell.
Fun fact: Amongst german electical engineers, these are known as "Gleich-riecht-er" (lliterally translates to "he'll smell soon") which is a play on the german word for rectifier, "Gleichrichter"
was about to post this
There is an alternate fun theory, that the word, rectifier was a derivation of the phrase "rectum fire".
@@judonomobic That doesn't make any form of sense.
@@sn0wt1ger Neither does the Biden precidency but thats still a thing.
@@mikaellindqvist5599 More than the Former Loser!
An "advantage" of the old Selenium rectifiers is that they had a fairly high resistance, with a strong Positive Temperature Coefficient. Which meant that when used in battery chargers they would self regulate the charge current to a safe value. Even when shorted they would just get hot and (usually) not self destruct. I've seen a few old battery chargers where someone had replaced a damaged Selenium rectifier with a modern Silicon rectifier. Which meant that the first time they were shorted, they would blow the fuse (if it had one). A solution is to put a 60W incandescent globe in series with the mains input to provide the missing Positive Temperature Coefficient.
Totally correct, I have seen many transformers fry when people replaced them with silicon in battery charging applications.
An interesting idea, the 60W lamp, I assume you mean in the transformers primary.
I've had luck with halogen headlight globes in the output, more for short/overload protection than battery charging.
@@paulstubbs7678 (a 50watt 12volt halogen (or two paralleled) series wired between charger and lead acid is good for battery)
@@paulstubbs7678 it's a really old trick for current limiting, literally going back to the vacuum tube era. Not a good idea with switch mode power supplies, but everything else pretty much tolerated or thrived from that usage.
One downside, other than the high voltage drop of the selenium diode was, like electrolytic capacitors, they'd grow leaky just sitting on a shelf. Usually, like the electrolytic, they'd reform under use, but one had to recognize that and allow reformation to occur before final testing of a repaired unit.
I did run into an instance of silicon replacement creating problems, lower voltage drop, which was easily enough countered with an NTC thermistor.
Clive, my experience of these is the smell is nearer to swede than rotten eggs. While fault finding on a power station battery charger one night shift, we (three electricians for some reason, so before privatisation) came to a dead end. We sat thinking on a cig break, and one of the guys said " Has someone dropped one?". We all sniffed the air, and as soon as we agreed the smell was swede, the more experienced guy said "It's a selenium rectifier". Job done. Had the team consisted of more polite people, we may have taken a lot longer to find the problem...
"We sat thinking on a cig break, and one of the guys said " Has someone dropped one?"
🤣🤣🤣🤣🤣
I didn't know rutabaga had a smell...
Fascinating. I knew of these components, but not how they worked - and certainly not how they failed! The Wikipedia article on them says "During catastrophic failure they produced significant quantities of malodorous and highly toxic fumes that let the repair technician know what the problem was."
It's a design feature!
Seems like a nice neutral understatement.
I remember reading this ages ago and thinking "... we still use the stink to find where the problem is"
... It just stinks a LOT less apparently.
They literally were the origin of my ancient smoke emitting diodes joke.
And one of the few things that I actually could barely smell. Apparently, some odors aren't carried by the olfactory bulb, but via the trigeminal nerve, typically some of the nastier things get carried that way to the brain.
Early cinema carbon lamps used approximately 70 amps at lowish voltage DC. Usually using a selenium rectifier. I was called a cinema that had lost a show. On entering the foyer I knew exactly what the issue was by that smell. I returned to the car some some diodes. Everyone was really impressed that I could identify the fault without even going into the projection room. Those were the days!!
🤠🤘🙏
A while ago I came across a bridge rectifier made of these in a very old 200kV DC power supply. It had hundreds of tiny discs stacked up in cardboard tubes, dozens of the tubes in series, and the whole thing submerged in oil. Despite all signs, the customer didn't believe the rectifiers could have possibly failed, until they opened the tank and were hit by the stench. Several of the cardboard tubes had carbonized, fallen apart, and dumped their discs all over the bottom of the tank. Mouser sold us a lot of microwave oven diodes that day!
There aren't a lot of applications where a 200kV DC supply would ever have been needed. Was it a commercial broadcast radio transmitter? How huge were the condensors and valves?
you'd think they would have used selenium stick diodes
GE used this system in their VERY early medical LinAcs. Also fairly common (around this sort of voltage) in earlier X-Ray equipment, especially the high energy (high acc. voltage) tube systems used in X-Ray radiotherapy.
@@tactileslut I know electrostatic filters operate from 50kV to 100kV, not sure about 200kV thou. There are no caps or other components after the rectifiers, except the voltage feedback which is a big resistor divider.
I actually have several rectifiers made up of stacked discs in a phenolic tube with brass end plugs, they came in a box of surplus parts I was given, clearly never used; I wonder if they were from a similar arrangement.
Until about a decade or so ago I had a Halfords battery charger that I bought in the 1960s it was a long narrowish box largely filled with an enormous selenium rectifier about a foot long. It was just a half wave rectifier with no smoothing and I am not sure how good it was for a car battery but it worked for 40 years until it erupted in smoke. I still use the leads and croc clips on a solar battery charger so it sort of lives on
Lead Acids almost don't care about ripple. Some frequencies and amplitudes are actually good for conditioning the plates. :)
Thank you for that OZ, I find it interesting that Halfords were selling shit battery chargers, even back then. As these would clearly do their best to destroy batteries asap, it comes as no surprise that Halfords have always made very good profit out of Battery Sales...
it may have failed due to the rectifier material absorbing atmospheric moisture, some types i've seen 'painted', (mostly high voltage types) , i have a charger bought new in the mid 80s, also spookily halfords branded 😉, and it has a 'contact cooled' selenium rectifier, basically a stack of rectifier plates, no air gap inbetween, and bolted to a metal plate , to dissipate the heat , still works perfectly, at the moment 😉,
i think they fail because of this, plus heat, rather than just 'age', if painted/sealed and run cool, pretty sure they'd last much longer without issues
It was a darn site better for the batteries than the silicone diode equivelent
Selenium rectifiers made their way into consumer electronics as well. Radios and TVs had them. Sometimes you can do a replacement 1:1 with a silicon diode (1N4007), but in other cases you have to add a series resistance to get the voltage within range. This resistor is almost always required when replacing the selenium rectifier in a portable valve radio that runs from both mains and batteries as the valve filaments are DC and have to be within a specific voltage range. They were commonly used in televisions for a while as well, but in those cases, you usually didn't need to add a resistance, or there was already a series resistor (that usually fails) to modify anyway.
The US Navy is what really put the end to Selenium over here in the US. In the early 1960s, it was specified that selenium rectifiers were not allowed as silicon rectifiers were far more reliable. I'm sure this trickled through the military requirements over the years. Remember, this was back when it wouldn't be uncommon for a ship to have possibly a few hundred valves in service at a time.
As opposed to the few billion silicon valves typical today ...
Yeh, domestic car battery chargers often used selenium rectifiers.
Just guessing: If the voltage had to be as close as 1:1 as possible and have decent current handling, you could throw a few rectifiers in series (and snip their AC terminals). Not as cost effective as a resistor on low currents, but can drop ~2v per package with a bonus heatsink & mounting setup.
@@TinWhisker for sure. People do the diode string trick when switching out a tube rectifier for silicon as well, since a 5Y3 may drop as much as 50-60V, or in general if B+ is too high (higher modern mains voltage, un-ideal transformer etc). Using zener diodes between center tap to ground is a common method. Can drop tons of voltage with a few diodes.
In small radio sets, it's not really worth the effort. I've swapped selenium out of small hallicrafters shortwave radio. It actually worked just fine without a dropping resistor, but I added a low value one to get the voltage closer to schematic measurements.
I remember them from my TV repair days. That used nappy smell was a great tell tale.
Selenium is indeed photoconductive. Laser printers use a selenium coating on their drums to transiently store a charge from a corona wire. The laser (or LED) exposes the areas not to be printed and those discharge back through the aluminium drum. The unexposed areas hold a charge and pick up toner with it. After depositing the toner, a light exposes the whole width to clear it and the cycle starts again.
Photonicinduction has an old video about a welding machine with selenium rectifiers. As you can imagine, the stacks were absolutely ridiculous in size.
Yep just left a comment about that! I’ve got stacks of these things that either came out of old welders, or new old stock replacements. Some of them must weigh over 20 pounds, about the size of a 3 gallon bucket!
I sure as hell don’t want them or have a use for them.
It's not a welder. It's from an old cinema to power the arc lamp.
@@TheManLab7 oh yeah you're right.
Here it is btw: th-cam.com/video/t_YBOfnS__Y/w-d-xo.html
I've got a 1956 P&H 400 amp AC/DC welder...selenium stack in there....plates are many 8-9" square... maybe 60+ of them, big fan blows on them all the time machines is on....machine still works as well as most modern ones...I can do the 'Aluminum' can or 'Razor' blade welds just fine. it goes down to 3 amps....
@@TheManLab7 years ago i worked cinema arc lamp projection, one night a selenium blew, not nice
Selenium was also used in the first solar panels, installed on a rooftop in New York, in the 1880's. Just like the diodes and other components, the selenium was later replaced by silicon in the panels.
Of course the one thing, the film Evolution taught us, is there is also selenium in popular dandruff shampoos.
Those were ZnSe based cells IIRC.
Selenium is used these days in CIGS (Copper Indium Gallium Selenide) solar cells, which were a big thing years ago as they were at the time cheaper than silicon cells, but their use has died out in most COTS PV modules as silicon prices cratered in the late 2000s and 2010s.
We need tiny amounts of selenium in our diet, usually from leafy greens, to have healthy bones and teeth.
WOW, had too look that up,.. i'm so impressed by the past... people came and went , cities built and destroyed, all before we were born
That was a good film but the ending was rubbish.
Selenium is still used in some photodiodes. Photodiodes are just mini solar cells, so I suppose it makes sense.
Rotten Eggs smell is usually code name for the smell of various Sulfur compunds.
Selenium (34) is the element just below Sulfur (16) in the periodic table and if remember the "Things I Won't Work With" blog correctly the smell is similar but gets MUCH worse as you move down in the that column, so it would make sense that Selenium diode failures could result in the kind of smell you describe.
My Dad used to use Selsun dandruff shampoo. As the name suggests, the active ingredient is selenium sulphide. Lovely stuff.
The next element below Selenium is Tellurium. If the rectifiers had been made with Tellurium the smell would be 10x worse.
@@tonywalton1464 Hey, I used a sulphide shampoo for my dandruff back in the day as well. Turned out I actually just had a really sensitive scalp and that shampoo took me all the way from lots of dandruff to bleeding sores, so I suffered the smell and then kept on suffering!
Eggs? Even rotten? Not even close, more like severely rotten garlic with hints of cabbage. It soaks into the walls, and stays there for years. My grandpa's workshop still has hints of that smell, 25 years after the failure. The element itself isn't too terrible to handle, "trollurium" is much worse 😸
@@CuriousFocker Was told this about tellurium by my chemistry teacher in the first year at secondary school. Apparently it affected the breath of the miners too.
Its actually give me nice idea... what about adding "smell" to electronic components so we know what break down? Like adding strawberry flavor to Capacitor, so when it blew up we will know to replace it? And make it in form of small blob that react only when heat is applied so it "release" smell only when specific temperature is reached that normally pop up capacitor. And the same thing for diodes or resistors... It could actually work...
I really like this idea. You could assign smells to each of the digits in the value of the the component, so combined smells would allow you to identify the value of component that had just failed. ‘Mint chocolate rasberry? Well that’s a bad 1k ohm resistor’, you would say.
@Akinaro @@jastervoid You two are a couple of flippin' geniuses!
There is a fine line between "genius" and "idiot"
@@drakefallentine8351 Yes, components already stink in their own ways when they fail.
When a cap sharts itself, the smell is a dead giveaway.
If you've ever "smelled semiconductor" when a transistor or diode failed; you know the smell of burning silicon - which is readily distinguishable from burning PCB / resistor etc...
These smells are faint however, at least when compared to selenium rectifiers - I'd hate to have my house stink out when a diode in the TV fails!
Um, some types of capacitor (paper based X2 class interference suppression types for example) already will give off a distinctive foul smell (good enough to clear a room…)!
I always thought the fins were just heatsinks, and the bits between them were the diodes. I remember seeing them in old TVs and car battery chargers
Woah, i've been assuming wrongly for years...
I have an old car battery charger with a selenium rectifier inside. I don't have a car so was going to sell it on eBay. After watching this video, i definitely need to replace the selenium rectifier with a moden silicon one before selling it. I wouldn't want it to fail with that horrible smoke.
@mikeselectricstuff you are correct, the fins are heatsinks, the selenium discs are in the middle being compressed by the bolt, i've taken a couple apart before..
I have a selenium rectifier that is about 3" square, most of it is thin aluminium plates, the discs are about 3/4", the middle terminal is between 2 of the discs with no plate, it came from a car battery charger, of about 10 amps, notably the charger had plenty of vent holes
@@simontay4851 depends upon the condition... If it was in good condition i'd personally buy it only because it was original... But sometimes you can't be 100% original, capacitors are a perfect example.
@@simontay4851 I don't know where i heard it (many years ago), but one reason for using selenium was 'because' of the volt drop, many people turn on the charger before connecting it, then touch the clips togehter, or they connect to a very flat battery, from what i was told, th selenium rectifier could take a quick overload, i think modern chargers with silicon also have an inductor in series. i may be wrong on this.
I’ve changed a lot of these. Back in the day replaced them using the BY100 ‘top hat’ silicon diode which was the forerunner of the 1N4007. Record players and tape recorders often used the small aluminium cased contact cooled selenium rectifiers by Siemens, Westinghouse or STC. The smell wasn’t great when they failed but there’s an industrial two part underwater epoxy that when mixed smells like dog **** and seems to stay with you long after you’ve finished using it - give me the selenium smell any day!!
I've had those things short circuit.
I've never smelled one burning up, but as an electronics buff kid in the 70s I took apart a few old discarded things that used them. My character of a Grandpa who worked on electronics since the 30s was very vocal about what a selenium rectifier smelled like when it burned up- *a dirty fart!* He also called them rectum-fryers.
That also translates into German: Gleichrichter = rectifier, "gleich riecht er" ~ "getting smelly", nickname for selenium rectifiers.
Sehr gute Bemerkung :)
Ya Jens, Das translates auch zu "Stinken Scheisse Rauch Nasehalten Clivenarsch Hose."
German has some of the best puns.
@@Mike_Hughes No gefingerpoken! Only watchen the blinkenlights, ;)
@@kaitlyn__L It really does. They have one for FIAT (the car manufacturer) and they have an acronym which from it which basically means "problems in every part" very cunning linguists.
Edit:
It's "Fehler In Allen Teilen"
PSA for those who wanna experiment with those individual plates: the coating (of the semiconductor, i'm not thinking of the paint) contains cadmium, which is really quite bad.
Use gloves when you try and fool around with it, and avoid any sanding/scratching of the surface layers!
Cadmium....yeah, really bad when heated, that's why they removed it from silver solder, although it really made the solder 'flow-out' very well.
@@dougankrum3328 Old soldering wire was really something great, but I'm glad they've mostly done away with it. With modern lead and cadmium free solder you'll be fine as long as you've got good Flux
Nah experiments are more fun when there's risk involved
@@Kyharra Yeah, but I like my bones.
@@qwertykeyboard5901 bones are just temporary energy is eternal
Clive speculated on the use of the fifth diode in the stack. When choke input filters were used, the choke means that current flows continually, so a fifth diode shunted the bridge rectifier, to provide a path for this current when the bridge diodes turn off. Without this extra diode, circuit operation is a lot less efficient and the heat dissipated in the bridge diodes is a lot higher as the choke will try to force the diodes to stay on. If the filter has an input capacitor before the choke, the fifth diode isn't needed and was not included.
So, combined with a neon "F.A.R.T." transformer, this would make a good stinkbomb? :P
Now just put an ionizer on it!
I did something similar: Electric arc with a 7kV 50mA F/ART neon transformer heating ammonium bicarbonate.The entire room and the kitchen next to it had the nice smell.
I used to own one. 15 kV . One hell of a device. Happily sold it for 120 € I think some time back. 😏
When I first started my electronics hobby in the 60's, I used selenium rectifiers for 150V and 250VDC power supplies, for valve based radios. Don't remember them stinking, but then I never had a new one. Still, memories can be fun. Thanks.
They release acrid smoke when they catastrophically fail until all of the doping is burned away. If you had working selenium rectifiers or long dead rectifiers, they wouldn't smell.
@@mayshack Well, there you go. Never burned one up. I over-designed my radios.
Memories of FOUL 💩 SMELLS are not fun! 👎😂
@@marcse7en Well, I would agree.
They don't stink when new unless you short something out that puts too much current through them. They stink a filter capacitor in a radio failed and the rectifier blew.
I did four years as a navy engineer and our older ships (built in the mid-1960s), and even some of the older individual systems on our newer ships, have all sorts of these rectifiers scattered throughout the various control circuits.
I never actually knew what they did before now, and always just assumed they were some sort of heat sink around some sort of fusible link. Thanks for sharing!
Great Video!
I own a private telephone branch exchange made in 1963. It has one of those rectifiers which still works! It’s all huge relays and capacitors, no semiconductor at all! I can take some pictures for you if you like.
Yes, those rectifiers are photo sensitive.
They used to make selenium light meters for cameras. A lot of cheaper Super-8 cameras had them until the early 1980s. There was a little meter inside the viewfinder or on top of the camera body and you had to keep the pointer inside a rectangle in the center by adjusting the aperture. There were not linear at all, but all that mattered was to keep the pointer inside the rectangle.
The smell of them is really bad. In Germany, we like to call them “Gleich-riecht-er”. A rectifier is “Gleichrichter” (Gleich = same, Richtung = direction, so the word literally means “Same direction worker/contraption”). A small change in letters and pronunciation turns it into “It’s about to reek” (Gleich = soon, riecht = smells, er = he/it).
The major downside of them is that they always have a great leak current. The leak current actually helps them to operate in a stack and distribute the voltage evenly. If you want to stack diodes, you need to add resistors in parallel to each or some diodes get much more voltage than others and fail. The selenium rectifiers have those resistors built right in.
When the leak turns worse (with aging), they heat up until they fail.
In the TV series “Mission impossible” (1966), there is an episode (24, “The Train”) where they simulate a train journey inside a hangar with a train car sitting on pistons and a complex system of tapes and amplifiers creating the sounds. Barney, (the engineer) is sitting in front of his consoles when smoke starts to come out from under his seat. He instantly tells his boss that there is a rectifier is going to fail soon but he can hot-swap it without interrupting the simulation. And then you see him doing it using a spare and jumper wires.
www.imdb.com/title/tt0649356/
I like this TV series. Almost all the technical stuff which was next to impossible back in the days can be easily replicated by any good maker nowadays. They remote controlled a truck (like the Mythbusters), used a remote controlled drone, they even used some kind of RFID in a poker tablecloth.
It's funny you mention pinsetters, I've had to replace many of these in my Brunswick A2 pinsetters dating all the way back to 1956. I'm pretty sure I still have one or two original rectifiers, they are absolutely massive in size.
When they go out, everyone in the building knows about it, they're that stinky. For some reason I'm still able to buy them new via my supplier, but I always choose to get silicon rectifiers cheap via Mouser.
Another funny note, is that Otis Elevator company manufactured the Model A pinsetter for Brunswick for the first few years!
Normally, when someone tells me something like, this smells completely awful, I take that with a grain of salt and move on.
When Clive says it, I have absolutely no desire to be in a one kilometer radius of the failed part.
sparkplug1018
I promise you, Oh..boy... they do pong.
It's very much like H2S, maybe it IS hydrogen sulphide..
Unquestionably...bad eggs or last night's vindaloo!
Embarrassing if somebody who doesn't know about them walks into your workshop!
@@MauriatOttolink Hydrogen selenide, H2Se. en.wikipedia.org/wiki/Hydrogen_selenide
@@bobweiss8682
Ah... That explains it. Certainly smells like H2S!
@@bobweiss8682 A late thank you!
I was next to a very old TV set when its selenium rectifier failed with a loud pop. The smell was unforgettable.
When I was a kid I got a selenium rectifier from my grandfathers junk box and took it apart and made several solar cells from the plates. The rectifier was similar to the gray one you have but the plates were larger.
Electronron1, what color was the cell I think I had one as a kid kinda brownish? liberated from a satellite program.
@@anullhandle If I remember correctly they were painted a light blue, but that was 60 years ago so I could be mistaken.
I’ve been following you for a couple of years and I love your simple yet effective way of presenting everything. No fancy set or green screens, etc.
*nods* eyes straight down on the bench, as if we have HIS eyes. 100% focus, no distractions.... ... well... other then baking cakes with high voltage.
@@ICountFrom0 his electron flow delicacies leave Gordon Ramsey speechless
Not to mention he doesn't even really edit the videos, they're just a single take or series of single takes appended together, yet he's good enough that you don't necessarily realize it right away.
Never ever begs for likes or subscribes or hitting that stupid bell. He just does his thing. It's the only channel I can think of that is 100% content and zero percent fluff.
On a large DC motor in 1972, I swapped out the selinium field rectifier for a modern one. 6 weeks later the field winding burned out. I had forgotten about the voltage drop in the selinium rectifier.
We had several old battery chargers many moons ago when I was an apprentice at the railways that had them (you literally used a forklift to move them!!!) and know that smell.... Yeah there was no way in hell you would be hanging around when one blew... An open septic tank on a hot summers day with a day old dead cow in it is positively roselike in comparison... They are RANK!!!!
Things to be nostalgic about, eh. Dead cow in a well was pretty bad for me.
Things leg tore off while trying to pull it out with a chain block on the bucket of the owners tractor. The smell was horrific and the sight more so. Who's up for a game of fishing?
In comparison, I always loved the smell of my grandfathers radio room. It had some interesting smell about it that his wife hated the smell of. I know that he also repaired electrical equipment for a number of services.
So I've seen some of these things on his shelves and never knew what they were exactly. Some small and others huge.
But they all had a funny smell about them. It's my preferred nostalgic memory.
I will however, never be able to get the mental image of "an open septic thank on a hot summers day with a day old dead cow in it" Out of my head. Why does my mind picture someone drinking a margarita while sorting that problem out, whilst pitying the bloke swapping out burnt selenium diode rectifiers, I must be a real oddball, I guess.
I started playing with electronics in the '50's and these rectifiers were used in lots of radios and TV's. Just thinking about them brings that rotten egg smell to mind. There was no doubt when one failed.
It was probably the DOG 💩! 👎😂
@@marcse7en :-)
Me too. Don't recall any of those rectifiers going bad, though (as opposed to old electrolytic capacitors). We used to call them "Philco Junk Sets". Probably be worth a pretty penny today.
Brunswick pinsetters came equipped with those, to convert power to DC for an electric clutch.
You could smell them from 10 lanes away when one burned out.
We now have the newer style bridge rectifiers installed on them.
I've had the mispleasure of replacing a few blown ones on my pinsetters, usually the older ones smell worse. I love the new silicon rectifiers, they work great.
Another great informative video Clive. Being an old geezer, these selenium rectifiers were state of the art when I was a youngster. A favourite use was in car battery chargers. Whether or not they had some current regulating characteristics I don't know but very often there was no additional current limiting in the charger and the forward voltage of the rectifier and presumably it's fins which made a good heatsink was all there was. If the selenium rectifier was replaced with a silicon one years down the line, it was necessary to add an high power resistor of a few ohms to limit the charging current in line with your comments. I have a selenium rectifier in a mechanical industrial clock from the fifties an it's still working, but I've put a mains tungsten lamp in series with it just in case it goes short circuit.
I've got a 40+ year old car battery charger with selenium rectifier, used when I got it...4 amps, works great....and I also have a 400 Amp 1956 P&H AC/DC arc welder with a very large stack of selenium ....it works about as well as most of the new welders.
Using a ballast resistor in series is a good idea, as Clive mentions, when converting a selenium stack or vacuum tube rectifier to solid state. I sorted out a Collins 51-J3 receiver where the previous owner replaced the pear-shaped old style 5U4 rectifier with a solid state module, but no ballast resistor was added. The increase in B+ was apparently more stress than the PTO oscillator could handle without permanently throwing the linearity off - that was despite having an 0B2 regulator tube right on the frame of the oscillator can. Sometimes a little thought before execution would be a good thing.
A blast from the past. I learn electronics use those rectifiers. The smell , was like rotting cabbage when they went pop
I had one of these stacks on an old CB350 Honda, vintage 1968. Glad the modern regulators are so much better.
LOL
Watching a Febreez commercial at the intro with "smells like a fart" on the TN was beyond hilarious.
I had no idea this type of rectifier existed but I absolutely love learning about this tech! I've just started my "career in retirement," as it were. I did my first project with 110 AC last week. In unrelated news, I've just had my first regulator release its magic smoke. I wonder what caused that? ;)
Electronics=Smoke, magic and mirrors. If a mirror gets broken it lets out the smoke which contains the magic. 😁
I managed to get a brushless motor in one of our laboratory robot arms to burn out at least some of its windings because of an incorrectly placed reagent cartridge that it tepidly poked against. I got weird looks when I opened the cover and exclaimed "I smell magic smoke, that can't be good..."
You know, I've never been able to find a small can of 'replacement smoke'....
@@dougankrum3328 😂 Don't forget to repair the cracked mirror before installing the new smoke.
What a blast from the past, a a babyboomer I remember playing with Selenium rectifiers as a kid. I don't remember the specific smell when they let out the magic smoke but it was pretty strong. Only much later did I learn about the harmful effects.
Given how nasty they are I'm surprised they are still available as replacements.
I only came across these a few times. One in an old elevator circuit. I was not allowed to touch this circuit as elevators are covered by another qualification with insurance applied. The other was in old control circuits in the steel mill I was working at for 10 years. They were replaced before failure even though they were very reliable.
There were also selenium "stick" rectifiers for televisions either on the EHT winding, or on the focus circuit for colour tv's
And if it FAILED, did everybody blame the DOG 💩? 😂😂😂
colooooor tv you say?
@@TheSaltyExplorer Yes, coloUr
If you cut one open, there is literally selenium rectifier confetti inside - tens or hundreds of thin sheet meal discs with a selenium dot in the middle that are the individual diodes, and a spring to push them together. At least that's what's in the Russian ones.
Krzysztof Czarnecki I've got three Russian ones myself. TV 13-03. 13KV rated. I've come across ones like Clive has and also small seleniums for higher voltage yet really low current.
I know that smell very well indeed!
The company I worked for used to manufacture battery charging equipment. They also wound their own transformers and assembled Selenium rectifiers.
The rectifier test department was definitely an area best avoided!
I smelled one of these for the first time today. I'm never going to forget this smell.
No, it does NOT smell like a fart, it's MUCH worse...!
When I was a kid, I put a little plastic box with a switch in the middle of an extension cord. The middle position of the switch was off, one side would directly connect things, and the other side would put a small selenium rectifier in line. Plug a lamp in and you had a sort of a dimmer. I was showing off this device to a neighbor lady after I'd gotten it built, and then progressed to trying various things out when it let that nasty smoke out. I'll never forget that smell.
Much more recently, a friend brought over a nice Grundig tube-based console stereo that he wanted me to fix because he liked the sound of it. I traced the problem to a bad rectifier, and was surprised to find that it was selenium. I put a terminal strip in there and some 1N4007 diodes, and it worked just fine after that. Finding a similar rectifier in my box of diodes, that one went right into the trash.
I have a couple of other ones around salvaged from something or other, painted blue. I remember these being in electronics stores I'd go into as a kid and being rated at "500mA". I've absolutely no intension of using them in anything, I just kept them because they look cool... :-)
You'd typically see a pair of these along with a pair of electrolytic capacitors in a voltage doubler circuit in some transformerless B&W TVs.
Not a minute of break with SAVORY videos from BigClive ! Thanks for all the flavors, with or without mains voltage !
This reminds me of when i was a TV field engineer. I could dectect a failed EHT tray by the smell that hit you as the customer opened the door..
EHT trays....I forgot about those !
I was also a TV engineer in the late 60's and 70's, and they used them as the mains rectifier with a 200V DC bus on the valve TVs, absolutely dangerous if you touched the live bus, we use to replace them with a BY127 rectifier if my brain is correct, also you had to make sure the bus was discharged before sticking your fingers in.
@@billyboy8820 It was a risky job back then.
Thank you Clive, that brought back unpleasant memories from fifty years ago.
My first permanent job in 1969 was reconditioning IBM keypunches and verifiers. The older machines used selenium rectifiers in the power supplies for the valves and relays. I was surprised by the stink the first time one failed in our large workshop. I doubt anyone's farts smell as bad! Imagine how bad it would be in a WWII aircraft.
Voltage drop was a problem in 1950s DC power supplies. E.G. Both my '00 Gauge' railway and my brothers ''Scalextric' required 12V but the transformer needed to supply 16V RMS. I would often trick my brother into leaving the track by cutting power to my car as he was approaching a corner! Adding a large capacitor to the DC output resulted in faster cars and little variation in voltage with load.
Yeah, 1969...for me it was the Telegraph Machines...the 'new' ones had electronics, transistors and still operated on 48 volts to work with the rest of the copper lines (that are still 48 volts). The teletypes used 120 VAC input, power supply converted to 48 Volts DC. They still needed 120 VAC as there were induction motors driving the printer and tape/keyboard decoder...all that was mechanical.....lots of tiny parts...100's of springs...
This helped me troubleshoot and fix a 1950's Lincoln Fleetwelder 200 arc welder with a non-functioning Arc Strike Circuit. Replaced with an ECG 400V, 40A PRV bridge rectifier - thanks!
I would describe the smell as a combination of sulfur/rotten eggs + garlic + an acrid burning resistor + bloated skunk critter on the side of the road.
The Dynaco stereo system my father built from a kit ("Dynakit"!) in the early or mid 1960s used a selenium stack rectifier in one critical circuit instead of a "normal" vacuum tube. I feel certain I read in the manual they used it for its lower noise, though now I cannot recall if it was in the preamplifier or the FM tuner component. I do clearly remember the rectifier was painted green. 😀
Probably the PAS-3 preamp. Used a selenium bridge in the filament circuit to run some of the tube filaments (probably the phono preamp) on DC to reduce hum.
Brings back memories, thanks Clive.
In the 70s and 80s my Dad had a small yacht with an Ailsa Craig outboard motor with built in generator. In the transom was a car battery fed by a blue painted Selenium rectifier having about 4 or 5 plates.
This is how navigation lights were run before silicon diodes and solar panels!!
Thanks for sharing this! I’ve troubleshooted an electric panel for a russian big lathe with several selenium diodes. I did not meet anyone who had that experience before. Big hello from Brazil all the best.
5:10 the extra diode would probably be the ground connection for the bridge, making the other negative output be available to supply a negative bias to whatever. This 'backbias' circuit was often supplied by feeding the bridge to ground via a suitable value resistor but in this case they've used a diode, possibly for a more constant voltage drop.
And yeah, the pong these things produced when overloaded was horrific.
Had one fail recently in one of my master clock controllers, fortunately it just went high resistance without much bad smell.
Hi Clive,
I recall in the '60's ., I often used to check the selenium rectifiers of the Ecko TV's with a series lamp of around 60 watts. If they were faulty it was easily detected and often they would arc and produce wonderful "farts"". Yes I am an old fart too!. Love your posts and please keep them up! Cheers, Roger.
When these failed on a TV( very long time ago) we'd bung a BY127 in, dead bug style, and the customer had to put up with the smell till it died away.
When tripplers went on TV's (selenium stick rectifiers), we used to tie the faulty ones for return to stores, to the back bumper of the van, so the stench was outside the cab.
You wouldn't believe the number of people who asked if it was a speed trap radar jamming device of some type!
I was playing with an old valve radio many years ago and something went pop. I couldn't understand how such a bad smell came from it. Now I know.
Issac Asimov has a story where the an outpost on another planet needs selenium for its power systems, and the robot goes mad while trying to get it.
Runaround, by Isaac Asimov.
It takes place on Mercury.
Back in the 1960's I was working as an apprentice Radio & TV engineer and these were quite common on older TV sets, when they failed we left them in place and connected a diode to one end with a wirewound heavy-duty porcelain type resistor in series then removed the other lead from the end of the failed rectifier and connected it to the wire wound resistor. The old rec was just left in place to support the diode and resistor.
This video brought back a stinky memory! I was in a college electronics class in 1971 and one of the students was doing a lab assignment. There was a question in the book asking what would happen if a capacitor shorted and the idiot shorted out the circuit to see what would happen instead of just thinking about it. I was across the room when I heard a loud pop and smelled one of the worse smells ever! He had shorted a power supply that used a Selenium Rectifier.
That's the reason why they were called "stink stacks" - that acrid smell.
I have a bridge rectifier that looks much like a selenium rectifier, but it has copper oxide on the plates. 🤔👍🤗
very small copper oxide rectifiers were commonly used in Volt-Ohm meters for the AC volt/AC current ranges.
Seems like a good option to get the Nosulous Rift back up and running... 😁
You'll have to root it to enable the sulfur extensions. (And for good reason!)
That smell is unique.
When my tube radio gave up, I immediately knew which component has gone.
Dear Clive, every time I tunein, you're dissecting an old nemesis of mine, this, the rectifier from a 1964 Triump Tiger 650 twin. Big old rectifier about an inch and a quarter square, two tall, on an aluminum heat sink wasting the "excess power" generated by the Lucifer electrics, or more commonly known, Lucas, which seldom have sufficient, much less "excess electric power". On the other hand, components always dump voltage and heat regardless whether it's beneficial, or detrimental. You always bring back warm memories from my youth, back in the late sixties, early seventies. You can run that engine without a battery, rectifier, anything, enough to run the points, engine, straight on the ac generated, barely. Got over a hundred miles that way back about 76. Thanks, always a pleasure!!
Funny that you mentioned pinsetter.
I happen to be one of the last "A" Brunswick A-2 model mechanics. (Retired)
It's amazing how many A2's are still in use.
I'm currently working on an interface for them to utilize an open-source scoring and league tracking program. Would love to get in touch for technical advice.
@@SwervingLemon if you need any pointers let me know, I work on a lot as well. Converted As, A2s, Japanese.
@@SwervingLemon
Any time
@@EthanCGamer It's still on the horizon because I have to wrap up two other projects first, but I'll be taking you both up on that.
@@SwervingLemon
I designed a motor pause device using SSR'S.
Never produced it.
Motor would shut down after 60 seconds until ball detect.
Definitely a bridge rectumfire, then.
The very first electronics repair I ever did, as a lad of 11 or 12, was replacing the selenium rectifier and filter cap in my dad's Sarkes Tarzian table radio, which makes sense since the company that made the radio was a big manufacturer of selenium rectifiers. Named for the Armenian immigrant who founded the company, and an extremely important company in the history of radio and especially television---- they were at the forefront of TV camera and video electronics, and owned a network of broadcast studios. Look up the history of the man and his company, it is a long and fascinating story.
Interesting, I built a small radio from instructions in Electronics Illustrated in 1959 or so, it used a modern silicon rectifier...Sarkes Tarzian...for 60+ years now, I always wondered where that name came from....very interesting, because I'd already read a lot about Nikola Tesla.
The YT algorithm dropped this and I thought WTF for. Didn’t understand a thing but ended up watching the whole thing with interest. Guess the algorithm knows me better than I thought.
I had a few motorcycles back in the day that had them...
BMW 3 ccm longstroke
I find it interesting that both Sulfur and Selenium form smelly compounds and are both in the Oxygen family of elements in the periodic table. Their outer shells have the same number of electrons and exhibit similar Chemistry. Maybe these similarities cause them both to react with the odor receptors in our noses in the same way?
I would guess that it's to do with the common ion sizes of oxygen being smaller, the bulk of atoms infleunce their reactivity and shape of the molecules it forms.
I have two orange ones I've had since I was a kid. My dad got them from Bell Aerospace where he was project manager on the Agena rocket engines (Saturn and Apolla rockets). My dad passed away last September, but I recently ran across those two diodes. Thanks for the explanation and differences between selenium and silicon!
"I have two orange ones I've had since I was a kid."
Should probably see a doctor. 😁
Thanks for the interesting video. It brought back memories from my days doing maintenance on 3 kw Telefunken FM transmitters in the 70's. The output amplifier ran at around 3.5 kv and cathode current was around 1.2 amps. The 3ph rectifier was made up of multiple banks of selenium stacks.
I don’t know why but “Went the way of things that go out of fashion. It went out of fashion” is just really pleasing to me for some reason.
I love non-silicon semiconductors. You can tell the ways they led to silicon’s eventual dominance. But they’re also very interesting unto themselves.
I also like seeing older sci-fi which assumed we’d still be using germanium and selenium and so forth hundreds of years from now.
Which makes me think about how 2D material research is only just in its infancy with graphene. And how we’re finding various doped semiconductors are just as useful if not more useful than pure carbon in the same kind of lattice for certain uses. You have to imagine they’ll find many more such uses in the next few centuries, with more and more specific formulations.
So modern sci-fi which says the computers are graphene… might sound as silly in the future as the earlier example I gave!
You've got to blow one up on camera and inhale the fumes whilst giving us a live report! Do put at least two or three cameras onto the subject of destruction just in case of awesomeness ensuing 😁😁😁
Thanks for shouting out to the bowling pinsetter maintenance world! That's where I use the old school selenium rectifier.
That's one of these times where I WISH we would have Smell-o-vision.
I remember the videos of clive blowing stuff up and tearing down big stuff - Now I slightly wish I could experience him letting out the magic horrible smoke, we both nearly choke, have a laugh and then go and have a pint.
I really love the videos and I always have the urge to pop on ebay and buy random stuff to just tinker with it.
The particulate/smoke is a dirty red colour. You could often see which layer had failed.
Went bang and stank the whole room out.
I can imagine everyone running away while coughing and gagging either thinking someone just shit themselves or the rectifier failed.
I just noticed Clive you don't have a three phase full bridge rectifier with the four that you talked about which I'm guessing is an entirely different type if rectifier compared to the ones you talked about.
Basically the same with two extra diodes.
You need to watch the latest Great Scott video, he just uses the German word for a three phase full bridge rectifier (literally a six-pole full bridge rectifier, sechspull-something)
@@rpavlik1 Sechspuls-Brückenschaltung is the word you're looking for :)
Thanks!
I've known about these for 30 years but never knew why they looked like that! My first bike, a Honda CL175 had one under the seat. It was probably the only part of that bike I didn't replace, mess with or bother to learn about, as it always charged fine. I recently restored a CB175 for a friend and seeing that bright orange selenium rectifier under the seat brought me back!
Model railroad transformers up until the 1970's or so also used selenium rectifiers. I recall the transformers would give off a slight, odd smell when hot.
Selenium: "I stink. I'll give you garlic breath, metal mouth taste, awful BO and bleeding."
Also Selenium: "You must eat me or suffer selenium deficiency and ultimately die."
🤷♂️
Or, as some of us might call them, Satan's fart packs! Usually, if replacing a selenium rectifier with silicon in say, an audio amp, or vintage radio/TV, it's customary to insert a resistor in series to compensate for the difference in voltage drop between silicon and selenium.
I am 73 years old, but I never needed to replace a selenium rectifier. The closest I came to that situation is changing a 6H6 with a transistor. My cousin had an old Rogers Majestic multi-band radio, from about 1937-8. Ron told me that the radio didn't work and asked me to look at it. I had doubts about it but I found the 6H6 had an open filament. He had no money, I had about the same, so I worried about it and decided to replace the 6H6 with a silicon transistor that I happened to have. The radio worked until he died 45 years later.
Always watch your vids, never leave a comment telling you how interesting and enlightening your content is, and how much you absolutely deserve to be on the front page of TH-cam. THAT CHANGES TODAY.
Imagine eating a whole jar of pickled eggs and then laughing so hard, you shit your pants! Oh the stank!
Whenever I try to type the word s**t, I get a WARNING on Pinterest! Is s**t allowed on TH-cam? 👍😂
Get a case of White Castle sliders go to the bar eat them along with the pickled eggs and a few beers and the next morning you can clear out the office ! We used to do that to dispatch when we got forced to work Saturday !!
i was eating at a burger joint a long time ago, and the little girl in the corner with her family say " ewwww smells like egg " 30 seconds later i can confirm the fart smelled like egg
@@marcse7en In comments never had any problem with it, or any other swear word for that matter. . In the video, I don't know.
I’ve replaced so many of those damned things, and dread it every time!
You’d be surprised how common they are, in industrial and precision test equipment.
I get a them sporadicly every few months… From a wide variation of clients and equipment.
Finding a substitution, can be difficult if it’s damaged or has no identifying marks.
And in many cases, it’s in a device that’s either really rare, or so old there’s no available documentation/pictures.
Damn hard to find a substitute, if you can’t identify the original or characterize it in anyway.
Can be a real bitch.
Especially if you’re an idiot… like myself🤪😁
If it's in such old devices I wonder if those companies owning the equipment got rid of the service manuals at some point. Depends a bit on the market segment but I remember a lot of old equipment coming with useful diagrams and specifications, unlikely to see that today for most stuff as an end user.
One blew up in Radio Shop in my High School (1969). It smelled like a combination of rotten eggs and rotten garlic. Not too surprising since its chemical properties are halfway between those of sulfur and tellurium (compounds of which reek of garlic), and selenium is between those elements in the Periodic Table.
And yes, if I ever find one in a piece of gear I immediately replace it with an equivalent silicon device plus an appropriate resistor as required.
One site I used to look after (in the 1990's) had a 2kW AM transmitter from the 1950's used as an emergency backup.
It originally used Mercury Rectifier tubes. There were two of these in the spares.
When they were difficult to get, they attached Selenium rectifier stacks onto the tube bases. There were two of these in spares.
When selenium rectifiers became difficult to get, they soldered silicon diodes onto the tube bases. THere were two of these in the spare parts as well.
There was about 50 years of history on the shelf just in these rectifiers. The transmitter was replaced in the early 2000's and I don't know where all this history ended up.
Sorry to necro-post, but TH-cam just suggested this video today.
I worked in an old mill that used them. The winding machines used 90 volt DC magnetic clutches. The selenium rectifiers used were about 2 feet long and 6 inches square. I asked where they go them and was told they came from a B-17 from WW2. This was in the 80's. They had modern digital timers running the clutches relays and the old selenium rectifiers to get the DC power. It was a real crazy rig up.
These were common in old 405 line Television sets. When I was young, I disassembled many of these old sets, to extract the components. Being about eight years old at the time, there were very few components I knew how to use. The big line transformers the wax paper and big aluminium tin capacitors, and the focusing ring magnets. Later, at around 12 years old, I converted a few TVs to primitive oscilloscopes, using the audio amp to provide Y deflection and the frame amp to give a low speed X deflection time base. .
Old TV sets had a range of distinct smells, ranging from burning dust on the valve tops, scorched paxolin pcb resin, the result of the valve heaters, smouldering carbon from underrated potentiometers, to ozone from the EHT, but the smell of burning selenium rectifier, is one, that once smelt, never to be forgotten.
Selenium is toxic, though it is reputed to be in some anti-dandruff products. Chemists who work with its compounds can absorb it through the skin and develope very unpleasant body odour and garlic breath as a result.
When I was a kid back in the late 60s, I had a Matchbox-branded slot car racing toy that looked like a kind of cheap-and-nasty Scalextric setup, but instead of applying power to a pair of tracks, with pickup brushes under the cars, this toy had one central motor that drove a long spring around the track, and the cars had a plastic pin underneath that engaged with the spring, thus making the whole thin much cheaper as the cars didn't have to include a motor, and the system would work with any of the Matchbox toy car range.
Anyway, it eventually broke down and was duly dismantled, and the power supply for it (around 6V DC if I remember correctly) consisted on just a basic transformer and a selenium rectifier (no capacitor of course as it was just driving a small DC motor)
Since other products available at the time were already including silicon rectifiers, I get the impression that either the toy was already outdated when I had it, or the manufacturer just had a stock of ancient components that they wanted to use up
Was it a blue power supply? I may have had one that powered many of my projects for years.
I swear you are the only person that can make a rectifier entertaining & everything else for that matter.
One minute you are stabbing a lithium battery or playing with mini chainsaws then next your diagnosing a component on a pcb or carbonating a beverage.
By far the best subscription I ever made.
I was recently converting an AC garden light power supply to DC, managed to mix up the pins on the bridge rectifier and as soon as I plugged it in the smoke escaped. That was a silicone rectifier and it smelled bad enough. I can only imagine how bad a selenium rectifier would be.
BTW: I remember seeing selenium rectifiers in the old radios I played around with in my youth and they were common on motorcycles until at least the early '70s.
Nice to see your Dual Full-wave Bridge Selenium Rectifier, looks like it was configured for a specific application.
Long ago, while going for my EE Degree, I worked as a Test Supervisor at a nearby General Instrument / Radio Receptor Factory. They manufactured Selenium Rectifiers of all types and sizes. Most were dipped in Green paint. When they failed, I kind of liked the smell, more metallic than malodorous. Maybe I just got used to that smell, which has not killed me yet.
Failed Electrolytic Capacitors smelled much worse to me.
For those seeking the smell specified in the title of this video, try smelling a bottle of the "health" supplement NAC.
I came across this during my apprenticeship as a radio and tv technician. The German name for rectifier is “Gleichrichter” but the nickname for this type was “Gleich riecht er” which means it soon starts smelling. Yes and the smell is like rotten eggs.
When I was an apprentice with the Post Office back in the early 1970s I spent some time in the local repeater station. This was on the ground floor of an 11 storey building. A selenium rectifier fire in a Signalling Unit 18B (a 500Hz/20Hz ringer for private circuits) permeated through the entire 11 floors within a few hours of the event. It lingered in the repeater station for many weeks. Once experienced, never forgotten! Some interesting facts here sbout these rectifiers, especially regarding use in bzttery chargers. I have some relatively recent chargers ( manufacturerd in the past 40years or so) that still used selenium rectifiers. Now I know why!
When I worked at 'Home Radio' in MItcham about 1972, we were still selling these. Still working in some of my home made test equipment...
You are 100% correct on the odor they give off when they blow. Horrible smell that will clear your nasal passages!! And if you think a bad cold will save you, you are sadly mistaken as you will taste it instead. Once you smell it you will never forget it.
Old school! The first electronics I played with back in the 60's all had them in the power supply.
About a hundred years ago I repaired teletype machines. Some of the machines in our inventory were Kleinschmidt models 20 and 25 and they had selenium rectifiers in their power supply. Smelling like a fart doesn't begin to describe the odor these things produce when they burn out. At worse its more like burning flesh. The only time I experienced this odorous treat I would have gladly preferred a fart smell.
Just serviced my old battery charger and it is equipped with these selenium rectifiers and i was very faschinated by this technology.