You sir, are a master educator. I've worked in both K-12 and adult education/training for computer technicians. Your explanations,pacing, and use of visuals are awesome.
Great video but there's one very important thing missing at the beginning of the video. The capacitor from the microwave holds a massive amount of voltage and sometimes the resistor that is responsible for bleeding out the capacitor fails, creating a deadly trap for whoever touches it. ALWAYS SAFELY DISCHARGE ANY CAPACITORS YOU ARE WORKING WITH AND MAKE SURE THAT YOU ARE COMFORTABLE WORKING WITH HIGH VOLTAGE BEFORE YOU ATTEMPT TO BUILD THIS POWER SUPPLY. Every year people die because they put they hand where they are not supposed to.
@@davestorm6718 In other words (same meaning) a relay with normally closed contacts wired from capacitor to ground, when AC is being applied, will trigger the opposite, (open state) to allow the capacitor to hold electric charge. The event of failure of that relay is something to keep in mind.
I will add AWESOME since it was not used yet. I spent a career in electronics and related tasks, but I have never seen a finer video. Even for myself it presents great explanations and illustrations for a good basic ohms law review. I look forward to the rest of your presentations. I agree with the other constructive comments especially those related to safety. I might add a caution to remove all jewelry when working with these voltages. Safety here can not be over stated. Thank you
This is exactly the Microwave Transformer video that I have been looking for. Clear explanation of the process and most importantly clear explanation of how these transformers behave.
Excellent video, brilliant explanation. The power transformer still has a shunt in between the coils as well. I have de-shunted the MOT and used them successfully for zapping wasps.
My mind is blown, I have watched 10's of videos on microwaves, MOTs, and magnetron's, and this is the best and most comprehensive, you deserve more subscribers, and I'm sure you'll have them if your other content is as great as this.
So true. See how many questions on what it can be used for. Even in a professional electrical context, such a device would require multiple layers of isolation safety and certainly not a 1 technician job. Personally, I reckon it is negligent posting such videos for morons to copy. If there is some 'need' to demonstrate Ohms Law calculations, etc, then do it at low voltage level.
When i was 18 or 19 i built a slightly less lethal version of this and wired it up to the metal sprung seat base in my Opel Manta to prevent it from being stolen, i powered it from 1 of the battery packs from the Power Banks we used to manufacture they were 5 ah 2.2v yuasa cells in series giving a 50 volt supply i think it was. I had a warning label printed in the windows and the car never gad an attempt made upon it to steal it.
Great comment I have worked in the comms field since I was in my teens ( now 67 ) and I have a healthy respect for any voltage. I still got zapped pretty bad by accident had HV transformer on a static mat I know conductive didn't register this was a danger. !! My fault.
I really enjoy your way of presenting all the components. I wish more people would be as educational as yourself. thank you and kudos for a great learning experience 👏
So much here to appreciate. A very well organized sequence with supporting calculations, consistent tempo and a great lecture voice. Just outstanding. In this design, I can’t help wonder about output lead insulation proximity to the enclosure face holes, and potential for plasma arcing through the chassis. I see great care with the panel face wing nut lugs, but the two cables seem very close. I’d love to understand how he arrived at the cable insulation.
I am totally in awe with the cadence and speed of your lecture. Most of the electrical stuff is beyond me but I am now studying how you speak in the video. I hope to emulate you (in a different subject). Thank you.
Brilliant. I happened to have all the components around to follow along and build. I did have some beefy resistors and a 40k probe, so I was able to test my own numbers. 6,303Vdc with no load. I learnt so much from this. Thank you.
aaaand, the good youtuber I found who's explaining stuff using the right ways that work with my brain, he actually stopped making videos years ago, this is happening too often, very sad.
Kudos my friend, that is probably the best explanation of a proper calculation test of any power supply I've ever seen and heard. I can't wait to see some of your other videos and I will be building one of these power supplies with of course a active cooling fan. Thanks again
One of the best electronics youtube videos I have seen. In fact I will just rate it the best! You would make an excellent teacher for electronics, as the best teachers are the ones who can simplify a complex subject like you have with this one. An important video to teach right also, as safety is a massive concern here. Looking at the below comments, I'm not the only one who appreciates the clarity of this video. A big thank you for your efforts, so much appreciated! :)
Very much appreciate the detailed explanation and accompanying illustrations. This will help since my Tesla inspired “coil for electromagnets” to convert concentrated solar power driving a Tesla turbine. Thanks for the help and tips for not getting pulverized.
What a beautiful , simple ,no nonsense explaination,……..! Speech so calm . Precise ! He seems to be a teacher with a degree in science , electronics ? If so , his students are very lucky….! Hardware design,…..impeccable , Like a Swiss Watch,……
Brilliant presentation. So clear and concise! I have built a couple of these with "full wave" full wave to get about 2kV. Be aware that some transformers have one of the HT leads internally connected to ground which makes the useless for this purpose.
Virtuality ALL microwave transformers have one external HV secondary connection, and the other leg connected to the chassis ground. This was clearly shown in this video. . The "full wave doubler" circuit shown here does not reference the chassis ground, it produces The high voltage (pulsed) DC is created between 2 terminals that are both independent from mains and chassis ground. . Therefore, all microwave transformers are suitable for this application, however 2 identical microwave machines will need to be disassembled to get the 2 x HV diodes and 2 x 2100V capacitors needed.
Yes, having one secondary lead ground referenced could mean trouble if the output of this supply had either the negative or positive output lead ground referenced. Also what about insulation resistance of the capacitors to ground?
Great video. I've used the same full wave doubler you use. Works well with zvs drivers powering AC flybacks too. You can double and even triple the voltage of your ferrite core transformers.
I use 2 of them and a full wave bridge circuit. Just feed the primary in opposite phase. Now you can ground the transformers case to safety ground and use the 2 hot leads with a single diode each for full wave rectification. I have bought identical cheap 1.2kw microwave ovens for exact this purpose. The combined cost is still cheaper than a new dedicated HV transformer. I remove the two heater winding and rewind them. One feeds the tube heater, the other produces 12V for the electronic and relays. I run a 1300w RF amp with that circuit and it works well. It can do 1500w when the amp is switched to class C for digital. Many microwave oven transformers are current limited by the use of magnetic shunts. One can remove those to draw full current from the transformer
Thank you for talking through all the steps in your video so clearly and completely. For safety reasons I would never attempt to build this project as I am totally blind: however I found your video informative and educational and really enjoyed the content and it refreshed a lot of my knowledge on power theory.
First off, I really enjoyed the content on this video. I'll consider this as a reference for my own projects using a uWave oven transformer based supply. Considering the potential danger here, I did want to make some comments on safety. Having worked at Los Alamos National Labs in the Pulse Power world for many years, I was made to go to extensive high voltage safety courses yearly. It was not my intent to be a nit-picker but some things I saw in the video *triggered* me so I felt I should say something. A. The leather/cotton gloves are a *no no*. If they become damp, or the working environment is humid, those particular gloves can be more dangerous to rely on than not using gloves at all. B. Your power switch (IMO) is too close to the work. One should create a safety operating procedure for working with high voltage that does not involve exposing the operator to undue proximity to the high voltage work to energize or de-energize the system. C. We were taught to *always assume the system is energized* and in the case of high voltage systems with storage capacitors, we were to create an operating procedure for safing the system. One component of safing the system was a discharging procedure, and then a safing (shorting) procedure. Typically the discharging was done with a *shorting hook* or some kind of insulated probe, a grounding clip, and usually an integral discharge resistor. Finally the system would be *strapped* or shorted across the output leads for maintenance, configuration, or storage. E. I recommend an insulated guard around HV connections to mitigate accidental contact of the operator against the terminals or creating an unintentional HV circuit with extraneous conductors that might come in contact with the terminals during operation. I thought the safety glasses recommendation was a very good one. Having had high power components explode and hit me in the face, I can attest to their value in this kind of work And finally, for your own safety, I recommend you lead your presentation with a disclaimer. :D
The large capacitors in microwave ovens usually have integral self-discharging resistors (either 1 mega-ohm or perhaps 10 mega-ohms), hidden inside the can but connected across the terminals. So if left alone for long enough, a device like this will eventually discharge itself. But for capacitors from other sources, where you have no idea if they might have internal resistors, I would agree to put a self-discharge resistor in.
Just found your channel, and yes master educator. I love electronics since i was 5years old. but i felt that math was for people that needed it. found out the hard way later in life going back to school. Thank you for your time explaining the importance of mathematics in electronics
Great video. I like the narration and the high detail. Also for explaining not just how to make the supply but where each component came from and what it's original purpose was.
@@mckanebullerlee3020 All high voltage transformers with a variac control have a built in limit switch at zero volt position in a holding circuit. So the high voltage will not be turned ON at power up. User has to bring the variac dial to zero to enable the unit. Regards
Better to have a switch, with a variac. It’s just basic safety measures of electronics of this lab “platform” type. Flipping a switch with instant 110Vac is risky business for specimens and yourself. This is highly dangerous video BTW!
Fantastic video, I would recommend to call the transformator metal for zero, and the two outputs for +3000 and -3000, just as your sehematic say at 23:22 Another problem is ripple at full load is very dominant, and at no load the 2100V rated capacitors are charged to 3kV, also an important note : some capacitors contain the diode, and also some times a 2100V "zener" in older owens the zener is a an extra diode acros the diode, and the normal diode is the one to chassis.
What an exceptionally clear and well-presented video and nicely-done project! I’m sad you’re not making videos any more, but I can on,y imagine the amount of effort that went into this. I’ve permanently filed this, as I’ve wanted a high voltage power supply for some time now :-)
HI Jim, I have never seen a video like this in my entire life and 20 years of experience in Electrical Engineering. You method of explaning with crystal clear details and calculations is beyond explanation. This is a must for electrical engineering student. I liked your video and shared it with my students. Thank you so much for tons of educational material in this very simple power supply design but it has a lot in it. Regards.
I taught myself how to fix microwaves as a young man I had my own buisness fixing broken electronics. I made thousands of dollars. I attended ITT COLLEGE but couldn't afford to continue my education so I went to the library and studied each day and brought my lunch
Best TH-cam video I have seen. I love that you know your material and you don't waist time. If I could give you an award for best video I would. I have kept the parts of an old microwave around for many years thinking I may have a use for them. Watching your video I was wandering what I would use a 6k dc power supply for?
An excellent video, with very precise articulation of the engineering analysis. Am curious about what you will use this for - possibly as the plate transformer for an HF linear amplifier?
This is too much voltage and too little current for any tubes that would fall into the category as linear amplification for SSB in ham radio service. Half that voltage would be about right and let you pull the rated transformer secondary current.
*WARNING!* Those attempting reproduction of Jim's design take note! The Output Terminal labeled *"ZERO"* is *DEADLY!* Properly labeled, it should read *Output Common* or at the very least ... *"Common"!* Simultaneously touching the *"Zero Terminal"* and Earth Ground, water pipes or any electrical chassis at ground potential could *KILL YOU!* Personally, I'd be labeling the "Zero Terminal "* with industry recognized danger symbols and graphics! Hell, at these voltages I'd be *EXTRA VERBOSE* with my labeling! Aside from that unfortunate oversight, Jim's video is excellent! Voltage Doubler circuit theory was clear, concise and accurate. The *Salvage and Re-purpose* segments were also excellent and easy listening! I subscribed within the first few minutes of it!!! Wakodahatchee Chris
Oops! I just noticed that your schematic indicates that your metal enclosure is not grounded! That's an industry standard No - No! Metal cases MUST be grounded when connecting to mains. As it stands now lethal voltages are present between the Zero and 6000 volt terminals and the Zero Terminal and the Transformer Core and any metal making contact with the Core. If I'm wrong, please correct me.
@@cdrive5757- the 2 x HV connections are not referenced to ground. Well, they are isolated by the diodes and capacitors so it's not 100% safe. The 3rd terminal makes no sense to me, neither does having huge exposed wing nuts o those terminals... totally irresponsible and unsafe.
@@cdrive5757 - well no, of course I didn't read "all the replies". Simply because there are NO replies, except for your second comment to yourself... ... I am the first person to reply here 🙄
Brilliant video and graphics for any budding young electrical engineer. Wish my early days electrical engineering lecturer had had the same skills as you have...some 60 years ago.
Thanks for the brilliant technical description. As below wonder what I would do with this power supply? Thanks for the video, looking forward to more of the same.
I was confused for a while since I've always used a straight line and an arc line to represent a capacitor and 2 straight lines in parallel to present a contact points after you explained it I caught on, great job at instructing
Yikes! That would make you the only one in the world that uses such a symbol, which is unsafe! There is an international standard: - The two parallel lines is ALWAYS a capacitor, and it is used when the capacitor can survive being charged in BOTH directions. - The one straight and one arc line is ALSO a capacitor, but a special sub-type that can ONLY survive being charged in ONE direction. - A contact point is A SWITCH and such are ALWAYS drawn with a conductor-line that is broken at an angle, such that if the angle is straightened out the whole component just becomes a straight line.
Thank you. I think you explained this quite well and still accurate while leaving out a few more technical physics matters. It is interesting how often these units are often thrown away while there are components that still have many years of life left. Thank you for your video. I am going to build this and maybe add a voltage doubler to have a nice gas laser power supply.
I love the amount of information and extensive education in basic electricity. Great video, thank you for the upload. Although, this video is extraordinary in it's information and instructions I fear it is lost on 95% of those watching it as they don't want the how and why's of the project, they want the black and white, "put this there and that's there" mindless instructions. Society today has been groomed for zombification and care nothing for the education over instant gratification. Sadly.
As stated, he did a great job of going through all of the math, and explaining everything, how ever you seriously scrued up on the output, as you mentioned it is a doubler, and if you were using a supply transformer with a floating secondary, you could call the output "0 & 6,000 volts, but that is not what you have. Because the transformer secondary is one end grounded, the output is actually two 3100 volt half wave supplies in series, which is a plus and minus 3100 volts to chassis, so by labeling the one side 0 volts and the other 6,000 you have given a false representation of what is actually present, and if someone builds this Supply and connects the 0 volt side of the power supply to the chassis of there project, it will cause the power supply chassis to be + 3100 volts above the chassis of there project. And I can tell from your explanation of the build that you are smart enough to know how dangerous this could be. I'm sure it was just an oversight, but a dangerous one at this voltage level, as you mentioned, it's well inside the lethal range, so please correct this on your video before there is a tragic accident!!!
Oops! I just noticed that your schematic indicates that your metal enclosure is not grounded! That's an industry standard *No - No!* Metal cases MUST be grounded when connecting to mains. As it stands now lethal voltages are present between the Zero and 6000 volt terminals and the Zero Terminal and the Transformer Core and any metal making contact with the Core. If I'm wrong, please correct me.
Just in case someone still wonders about the ground. The metal case is grounded by the green wire connecting the middle prong of the power supply cable and the metal case seem at 25:27 in the video. So you would need to use good 3 prong power supply cable on a proper 3-prong grounded outlet. The author mentioned he used a computer power supply cable for it.
Great sir highly apprciated and greatceffort and well scoped video and very very well elaborated for every single person hope to see your farther videos
Very meticulous,comprehensive explanation👍...It's like when I'm explaining for my buddy the repair of his guitar amp,he is about to go haywire🤣....but I don't go to this much details.Well I'm having fun of course😀
Oh yeah, FEMALE output connectors would eliminate a SERIOUS shock / short accident...which will happen sooner or later in this front panel design! THANKS AGAIN FOR THE GREAT VIDEO!!
Good, educational video, but people, pleaae learn the AC/DC rectification fundamentals on low voltage. I advise against building this particular arrangement. The primary winding on the transformer is NOT designed to work on floating 3kV level. It works only because a well built transformer uses huge safety margins (and required to be HiPot tested). Look at how much insulation is on the secondary side and almost none on the primary! Several aspects of the mechanical build is also a major safety issue. You do NOT use wing nuts and bare metal connectors on 230V even, let alone at 6kV. The output terminals should be insulated and a connector rated for at least 6kV continuous use should be used. There should be a visual indication that the output voltage is present on the terminals. Ideally it should continuosly indicate as long as the voltage is still above 50V (!), even when the primary is switched off already. There should be some sort of interlock which is, when not enabled, does not allow switching on the output. HV capacitors and test circuit outputs are usually required to be SHORTED to each other and to earth when not enabled, otherwise it is UNSAFE to touch. On typical proper lab testing systems one level of interlock on the safety enclosure is responsible for shorting the outputs and a second level to enable the HV power. This seems ridiculosly complicated and inconvenient but the energy and voltage at these levels can kill you instantly. Like PhotonicInduction said: You will be dead before you hit the floor.
Great instructional video you have here. I like it. Your description of the oscilloscope is very good. Could you do an O-Scope video on operating a Scope from a newbies point of view, please? I would like to see what yo come up with!
Yikes! I'd be nervous working with a HV PS that has a metal chassis and metal wing nuts, even if I built it. I would want an internal metal chassis but an external plastic or wood case. Large banana jacks for the the connections and a plastic switch for on/off. Still you have to be mighty careful working with the output!
I really appreciated this video. Unlike some guys on TH-cam who endanger themselves and others you clearly know what you're doing. Also, got to love a Tek 475!
Excellent description of the circuits. Great job. I work with high power high voltage daily in my job. I like this project very much and don't want to see anyone injured and that pain placed on you. As well as possible legal liability. So, please let me share a few critical observations. 1. This IS NOT a project for beginners. Period. 2. The meter you are using at the 30:00 minute mark is either 20K/volt or, worse yet, 1K/volt. That will present a 20K ohm load in parallel with your sense resistor giving an inaccurate reading. Take this resistance into consideration as well. I calculate this to be 952.3 ohms for the total sense resistance. 3. The output terminals on this supply are outright criminal. The relief openings behind the bolts are FAR TOO SMALL for safety. Please find some proper recessed high voltage terminals and matching plugs. It is far too easy to contact these terminals and DIE INSTANTLY. 4. Go to the automotive parts store and purchase spark plug wire, 20KV break down at a minimum, for your leads. I use 40KV rated wire on my 6KV supply here in my home lab. 5. You should bring out the ground and then relabel the out put terminals "+3000V" and "-3000V", labeling the ground "0V". This gives the option of a grounded 3KV supply ("safer") or a floating 6KV supply by ignoring the ground (0V) terminal. 7. If you place a variac transformer on the primary side of the HV transformer, you now have a zero to full voltage high voltage power supply. My commercial HV supply (Leybold) does exactly this. LAST COMMENT. You can see how I use my commercial high voltage power supply in my video entitled, "PhiloCam Part 16 - Power supply problem proven beyond a doubt".
12:37 for those who are curious about the number 0.707 which is the result of calculating Vpeak -> Vrms Vpeak*sqrt(1/2)=Vrms => Vpeak*1/sqrt(2)=Vrms both, sqrt(1/2) and 1/sqrt(2) ≈ 0.707 (well, 0.70710678… to be precise-ish) (sqrt(2)≈1.414 -> 1/1.414≈0.707) In the end, Vpeak/sqrt(2)=Vrms
THANKS FOR THE GREAT VIDEO!!! As an upgrade, you could put another capacitor in parallel with EACH of the existing two for more smoothing (two more caps). A volt meter using a voltage divider for calibration would be nice (maybe one for current also...this one would be easy to use as-is). A VARIAC at the AC input would make a great 'variable' DC supply. WARNING: Be aware that the variac can step the input above 120VAC! The only thing that bothers me is the voltage rating of the caps...close...espically if variac driven at the higher voltage region.
Good Sir - I used your tutorial - it is one of the best on TH-cam. Thanks! It worked perfectly. Now I have two questions, but first some background. - I wanted to throttle down the output voltage so I put a variac on the AC input. This worked very well when all I had on it was a volt meter. My project also calls for pulsing the high voltage. I am currently doing that with two solid state relays. One to connect the positive output to the load and the other to connect the negative output to the load. They pulse at exactly the same rate and are driven by the same driver - both on and both off at the same time. they are being pulsed on for about 50 millisec out of 110ms cycle time. I have to isolate the ground for my project. When I turned on the variac with only a minimal load with the outputs of the power supply hooked to the load through the pulsing relays, the variac started buzzing and then a wisp of smoke! I shut it down immediately. The variac has a 20 amp fuse but it did not blow. After my hands stopped shaking I removed the pulse, hooked it up to a voltmeter, and it worked just like before. Now for my questions - 1 Why would this happen? 2. Would it likely work if I pulsed the input to the variac instead of the DC output from the power supply? Thanks! Mark Cooper
Every time you disconnect the transformer, it produces a MASSIVE spike of high voltage high current "Back EMF" through the primary winding. This will often damage the solid state relays and is probably being passed back to the variac. Furthermore, there is a huge inrush current proportional to the point in the mains waveform when the power is applied. A microwave transformer is not designed for pulsed operation, but to run continuously for seconds or miinutes at a time. The control circuits of the microwave will have some small protection for the switching relay, to ensure that it doesn't arc too much. But these are nowhere need strong enough to protect against switching at about 10Hz that you are trying to do. . The bottom line is that you should use a transformer that's designed for pulsed operation, for example an automotive spark plug coil. To make your existing circuit work you need to add some seriously heavy duty protection against Back EMF on the primary side, and that will be complicated by the fairly high switching frequency.
Adding to my previous comment... if you are actually trying to run the transformer continuously the use Solid State relays to switch the ~5KV outputs... ... that cannot work, as the SSR's will almost certainly not be rated to handle that kind of voltage. . The SSR's are probably flashing over and creating a dead short circuit on the output side, or have already been completely fried. . The fuse on the cardiac will only blow at several times greater than it's rated Current. So the fact that it didn't blow doesn't mean that you weren't pulling >20A from it. If the load is pulsed then you might need to be pulling 100A at 50% duty cycle before that 20A fuse will open. In the meantime, the carbon brush is dying anyway, probably causing the smoke you saw. . BTW I overloaded my variac quite badly when trying to run it with small normal transformers wired "backwards" to create higher output voltages. There is something about the load profile of the transformer windings that creates an excessive current draw, even with no load applied to the output of my step up transformer.
I think you need to explain that anyone building this or messing with a microwave does so at their own risk !! You did say these voltages can be fatal, Im adding also cause terrible burns. I'm somewhat puzzled why anyone needs such a high voltage power supply. The only purpose I can think of is an RF linear amplifier. I shudder to think of an inexperienced person attempting to build this power supply or even attempting to probe these voltages. These voltages can jump gaps, and if you dont understand, please stay clear of this project. It will kill you !! I hope nobody is injured or killed after trying to duplicate this project. It is very dangerous !!
Thanks, for the great value, well set out,very clear and consice really appreciate a different perspective,a much more truer depiction, of current flow schematics 🧐✅🏆,
I fear these instructions will enable incompetent people to build something that is very damn dangerous! This thing can and will KILL YOU! I don't know the extent of liability for which you would be held accountable, but this is not something an untrained individual should be fooling with.,.. I sure hope no one gets killed.
Hi there and thanks for the upload, very informative but (as others have already said) as a professional EE, I must raise major safety concerns for any inexperienced or careless person who might try to copy your work. With the suggested wing-nut connectors and gardening gloves, and no power warning light, this is probably the most dangerous project I have seen recently. Please don't build anything like this if you have ANY doubts, and do watch my video about safety aspects of using microwave oven transformers. At least one person has been killed by a MOT. On the technical side, the transformer waveform is badly distorted because the core is heavily into saturation due to the cost-cutting with short windings and a narrow magnetic path. This saturation causes the transformer to pull more current and heat up even on no load. If you are stripping two microwaves, you can solve this by running two transformers, with the primaries in series and the secondaries in series, with the transformer cores joined to form a centre-tap which could be grounded through a high-voltage resistor for a slight safety improvement.
If you want to get a little more current out of it, remove the magnetic shunts from the transformer. There should be two little metal wedges stuck between the primary and secondary windings.
28:10 "of course, there's a risk of shock" - a wee bit of an understatement. 10 mA going through a flexor muscle will prevent its relaxation - grab that wire and somehow complete the circuit and you won't be able to drop it. An indicator light to know it's powered and some bleeding resistors across those capacitors would be good to have.
i’m not qualified to say this is a perfect video. but it’s refreshing to not hear distracting “music” or other ambient sounds, useless stuttering n suffixes n prefixes like um, ah, nnn boring us. clear pictures is really pleasing. u sound like my brother, an EEE. or r u an audiobook reader with that pleasant voice n good delivery? being a jack-of-all-trades, this wuzn’t totally satisfying 4 me. i’d preferd the last 15 minutes b used 2 show me the potential of this creation. :o)))
You sir, are a master educator. I've worked in both K-12 and adult education/training for computer technicians. Your explanations,pacing, and use of visuals are awesome.
It caught my attention that when you start loosing the context he switches and re gains your focus. Amazing skills.
Hands down, one of the best damn explanations of the electronic parts of a microwave and their function i have seen
Great video but there's one very important thing missing at the beginning of the video. The capacitor from the microwave holds a massive amount of voltage and sometimes the resistor that is responsible for bleeding out the capacitor fails, creating a deadly trap for whoever touches it. ALWAYS SAFELY DISCHARGE ANY CAPACITORS YOU ARE WORKING WITH AND MAKE SURE THAT YOU ARE COMFORTABLE WORKING WITH HIGH VOLTAGE BEFORE YOU ATTEMPT TO BUILD THIS POWER SUPPLY. Every year people die because they put they hand where they are not supposed to.
put in bleeder resistors over each cap - perhaps a relay that, when unpowered, engages the bleeders (so they don't interfere with the load)
Reading this made me feel a jolt go up my arm 🤣
@@davestorm6718 In other words (same meaning) a relay with normally closed contacts wired from capacitor to ground, when AC is being applied, will trigger the opposite, (open state) to allow the capacitor to hold electric charge. The event of failure of that relay is something to keep in mind.
those capacitors already have resistors built in
The capacitor holds up to 21000 volts
I will add AWESOME since it was not used yet. I spent a career in electronics and related tasks, but I have never seen a finer video. Even for myself it presents great explanations and illustrations for a good basic ohms law review. I look forward to the rest of your presentations. I agree with the other constructive comments especially those related to safety. I might add a caution to remove all jewelry when working with these voltages. Safety here can not be over stated. Thank you
Everyone seems to be impressed by the depth of the video… I was flabbergasted when he used the stick to point components. I wish everyone did that!!!
This is exactly the Microwave Transformer video that I have been looking for. Clear explanation of the process and most importantly clear explanation of how these transformers behave.
Excellent video, brilliant explanation. The power transformer still has a shunt in between the coils as well. I have de-shunted the MOT and used them successfully for zapping wasps.
My mind is blown, I have watched 10's of videos on microwaves, MOTs, and magnetron's, and this is the best and most comprehensive, you deserve more subscribers, and I'm sure you'll have them if your other content is as great as this.
It's a refreshing thing to see a man that's intelligence he is calculations are exactly right
😂😂Up
Anyone who needs this much of an explanation of Ohm's law and voltage dividers has no business working with such high voltages.
I agree absolutely.
So true. See how many questions on what it can be used for.
Even in a professional electrical context, such a device would require multiple layers of isolation safety and certainly not a 1 technician job.
Personally, I reckon it is negligent posting such videos for morons to copy. If there is some 'need' to demonstrate Ohms Law calculations, etc, then do it at low voltage level.
When i was 18 or 19 i built a slightly less lethal version of this and wired it up to the metal sprung seat base in my Opel Manta to prevent it from being stolen, i powered it from 1 of the battery packs from the Power Banks we used to manufacture they were 5 ah 2.2v yuasa cells in series giving a 50 volt supply i think it was. I had a warning label printed in the windows and the car never gad an attempt made upon it to steal it.
Shut up, loosers, it's survival of the fittest
Great comment I have worked in the comms field since I was in my teens ( now 67 ) and I have a healthy respect for any voltage. I still got zapped pretty bad by accident had HV transformer on a static mat I know conductive didn't register this was a danger. !! My fault.
This feels like a proof of one of those crazy questions from a physics textbook. Thank you for a imaginative learning experience.
Thank you for this magnificently produced presentation. I never leave comments but this one deserved it.
What a confident, clear explanation of how the microwave oven works and how it is to be used as a 6 kV power supply. Magnificent listening to you.
I really enjoy your way of presenting all the components. I wish more people would be as educational as yourself. thank you and kudos for a great learning experience 👏
So much here to appreciate. A very well organized sequence with supporting calculations, consistent tempo and a great lecture voice. Just outstanding. In this design, I can’t help wonder about output lead insulation proximity to the enclosure face holes, and potential for plasma arcing through the chassis. I see great care with the panel face wing nut lugs, but the two cables seem very close. I’d love to understand how he arrived at the cable insulation.
I am totally in awe with the cadence and speed of your lecture. Most of the electrical stuff is beyond me but I am now studying how you speak in the video. I hope to emulate you (in a different subject). Thank you.
Brilliant. I happened to have all the components around to follow along and build. I did have some beefy resistors and a 40k probe, so I was able to test my own numbers. 6,303Vdc with no load. I learnt so much from this. Thank you.
Superb! TH-cam needs more content creators like yourself! Interesting, practical, and educational. Just wonderful, thank you.
Outstanding analysis! And excellent explanations! Thank you!
aaaand, the good youtuber I found who's explaining stuff using the right ways that work with my brain, he actually stopped making videos years ago, this is happening too often, very sad.
Excellent quality! Very well explained as well. Keep up the good work.
One of the best explanations I have ever had the pleasure of following....
Very informative video. Nice explenation. Now i also know how a microwave works.
not one mention , of the Electrocution potential , how smooth is that!
Kudos my friend, that is probably the best explanation of a proper calculation test of any power supply I've ever seen and heard. I can't wait to see some of your other videos and I will be building one of these power supplies with of course a active cooling fan. Thanks again
One of the best electronics youtube videos I have seen. In fact I will just rate it the best! You would make an excellent teacher for electronics, as the best teachers are the ones who can simplify a complex subject like you have with this one. An important video to teach right also, as safety is a massive concern here. Looking at the below comments, I'm not the only one who appreciates the clarity of this video. A big thank you for your efforts, so much appreciated! :)
well said
Really good quality, and almost perfectly edited
Would love to see more videos from you. Just stumbled across your content.
Very much appreciate the detailed explanation and accompanying illustrations. This will help since my Tesla inspired “coil for electromagnets” to convert concentrated solar power driving a Tesla turbine. Thanks for the help and tips for not getting pulverized.
What a beautiful , simple ,no nonsense explaination,……..!
Speech so calm . Precise !
He seems to be a teacher with a degree in science , electronics ?
If so , his students are very lucky….!
Hardware design,…..impeccable ,
Like a Swiss Watch,……
Brilliant presentation. So clear and concise!
I have built a couple of these with "full wave" full wave to get about 2kV. Be aware that some transformers have one of the HT leads internally connected to ground which makes the useless for this purpose.
Virtuality ALL microwave transformers have one external HV secondary connection, and the other leg connected to the chassis ground. This was clearly shown in this video.
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The "full wave doubler" circuit shown here does not reference the chassis ground, it produces The high voltage (pulsed) DC is created between 2 terminals that are both independent from mains and chassis ground.
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Therefore, all microwave transformers are suitable for this application, however 2 identical microwave machines will need to be disassembled to get the 2 x HV diodes and 2 x 2100V capacitors needed.
Yes, having one secondary lead ground referenced could mean trouble if the output of this supply had either the negative or positive output lead ground referenced. Also what about insulation resistance of the capacitors to ground?
Great video. I've used the same full wave doubler you use. Works well with zvs drivers powering AC flybacks too. You can double and even triple the voltage of your ferrite core transformers.
I use 2 of them and a full wave bridge circuit. Just feed the primary in opposite phase. Now you can ground the transformers case to safety ground and use the 2 hot leads with a single diode each for full wave rectification. I have bought identical cheap 1.2kw microwave ovens for exact this purpose. The combined cost is still cheaper than a new dedicated HV transformer. I remove the two heater winding and rewind them. One feeds the tube heater, the other produces 12V for the electronic and relays. I run a 1300w RF amp with that circuit and it works well. It can do 1500w when the amp is switched to class C for digital. Many microwave oven transformers are current limited by the use of magnetic shunts. One can remove those to draw full current from the transformer
Thank you for talking through all the steps in your video so clearly and completely. For safety reasons I would never attempt to build this project as I am totally blind: however I found your video informative and educational and really enjoyed the content and it refreshed a lot of my knowledge on power theory.
I like your presentation. Precise and concise. I enjoyed it.
First off, I really enjoyed the content on this video. I'll consider this as a
reference for my own projects using a uWave oven transformer based supply.
Considering the potential danger here, I did want to make some comments on
safety.
Having worked at Los Alamos National Labs in the Pulse Power world for
many years, I was made to go to extensive high voltage safety courses yearly.
It was not my intent to be a nit-picker but some things I saw in the video
*triggered* me so I felt I should say something.
A. The leather/cotton gloves are a *no no*. If they become damp, or
the working environment is humid, those particular gloves can be more dangerous
to rely on than not using gloves at all.
B. Your power switch (IMO) is too close to the
work. One should create a safety operating procedure for working with high
voltage that does not involve exposing the operator to undue proximity to the
high voltage work to energize or de-energize the system.
C. We were taught to *always assume the system is energized* and in the
case of high voltage systems with storage capacitors, we were to create an
operating procedure for safing the system. One component of safing the system
was a discharging procedure, and then a safing (shorting) procedure. Typically
the discharging was done with a *shorting hook* or some kind of insulated
probe, a grounding clip, and usually an integral discharge resistor. Finally
the system would be *strapped* or shorted across the output leads for maintenance,
configuration, or storage.
E. I recommend an insulated guard around HV connections to mitigate accidental
contact of the operator against the terminals or creating an unintentional
HV circuit with extraneous conductors that might come in contact with the terminals
during operation.
I thought the safety glasses recommendation was a very good one. Having had high power
components explode and hit me in the face, I can attest to their value in
this kind of work
And finally, for your own safety, I recommend you lead your presentation with a disclaimer. :D
Thanks, you saved me the trouble.
The large capacitors in microwave ovens usually have integral self-discharging resistors (either 1 mega-ohm or perhaps 10 mega-ohms), hidden inside the can but connected across the terminals. So if left alone for long enough, a device like this will eventually discharge itself. But for capacitors from other sources, where you have no idea if they might have internal resistors, I would agree to put a self-discharge resistor in.
I wondered, if he got his pictures mixed up or something? Leather gloves is a no no and a no brainer for this application.
Shut up..
@@lloydevans2900 That's right. They're called "Bleeder resistors".
Just found your channel, and yes master educator. I love electronics since i was 5years old. but i felt that math was for people that needed it. found out the hard way later in life going back to school. Thank you for your time explaining the importance of mathematics in electronics
Great video. I like the narration and the high detail. Also for explaining not just how to make the supply but where each component came from and what it's original purpose was.
You have taken a lot of time patiently explaining things. A variac and a voltmeter at the primary wood be added advantage. Thank you
Variac integration would be a lot safer...
@@mckanebullerlee3020 All high voltage transformers with a variac control have a built in limit switch at zero volt position in a holding circuit. So the high voltage will not be turned ON at power up. User has to bring the variac dial to zero to enable the unit. Regards
Better to have a switch, with a variac. It’s just basic safety measures of electronics of this lab “platform” type. Flipping a switch with instant 110Vac is risky business for specimens and yourself. This is highly dangerous video BTW!
Fantastic video, I would recommend to call the transformator metal for zero, and the two outputs for +3000 and -3000, just as your sehematic say at 23:22
Another problem is ripple at full load is very dominant, and at no load the 2100V rated capacitors are charged to 3kV, also an important note : some capacitors contain the diode, and also some times a 2100V "zener" in older owens the zener is a an extra diode acros the diode, and the normal diode is the one to chassis.
this is so reminiscent of those old school educational films. pure delight!
What an exceptionally clear and well-presented video and nicely-done project! I’m sad you’re not making videos any more, but I can on,y imagine the amount of effort that went into this.
I’ve permanently filed this, as I’ve wanted a high voltage power supply for some time now :-)
HI Jim, I have never seen a video like this in my entire life and 20 years of experience in Electrical Engineering. You method of explaning with crystal clear details and calculations is beyond explanation. This is a must for electrical engineering student. I liked your video and shared it with my students. Thank you so much for tons of educational material in this very simple power supply design but it has a lot in it. Regards.
Oh my my. I have never seen a better explained video on the subject.
Very detailed and crystal-clear explanation. Well Done. Love it.
I taught myself how to fix microwaves as a young man I had my own buisness fixing broken electronics. I made thousands of dollars. I attended ITT COLLEGE but couldn't afford to continue my education so I went to the library and studied each day and brought my lunch
Best TH-cam video I have seen. I love that you know your material and you don't waist time. If I could give you an award for best video I would. I have kept the parts of an old microwave around for many years thinking I may have a use for them. Watching your video I was wandering what I would use a 6k dc power supply for?
ya, this is really really well done! Thankyou, im a beginner trying to learn and this was marvelous!! im in need of more powerful adjectives....
An excellent video, with very precise articulation of the engineering analysis. Am curious about what you will use this for - possibly as the plate transformer for an HF linear amplifier?
It's for a DIY Electric Chair. Doesn't matter if it's noisy.
This is too much voltage and too little current for any tubes that would fall into the category as linear amplification for SSB in ham radio service. Half that voltage would be about right and let you pull the rated transformer secondary current.
@@johntoe6127
Yeah, those exposed HV terminals are screaming "touch me, please!".
*WARNING!* Those attempting reproduction of Jim's design take note! The Output Terminal labeled *"ZERO"* is *DEADLY!* Properly labeled, it should read *Output Common* or at the very least ... *"Common"!* Simultaneously touching the *"Zero Terminal"* and Earth Ground, water pipes or any electrical chassis at ground potential could *KILL YOU!* Personally, I'd be labeling the "Zero Terminal "* with industry recognized danger symbols and graphics! Hell, at these voltages I'd be *EXTRA VERBOSE* with my labeling!
Aside from that unfortunate oversight, Jim's video is excellent! Voltage Doubler circuit theory was clear, concise and accurate. The *Salvage and Re-purpose* segments were also excellent and easy listening! I subscribed within the first few minutes of it!!!
Wakodahatchee Chris
Oops! I just noticed that your schematic indicates that your metal enclosure is not grounded! That's an industry standard No - No! Metal cases MUST be grounded when connecting to mains. As it stands now lethal voltages are present between the Zero and 6000 volt terminals and the Zero Terminal and the Transformer Core and any metal making contact with the Core. If I'm wrong, please correct me.
@@cdrive5757- the 2 x HV connections are not referenced to ground. Well, they are isolated by the diodes and capacitors so it's not 100% safe. The 3rd terminal makes no sense to me, neither does having huge exposed wing nuts o those terminals... totally irresponsible and unsafe.
@@johncoops6897 Did you bother to read all the replies to my original post 2 years ago? I think your comments were covered .
@@cdrive5757 - well no, of course I didn't read "all the replies". Simply because there are NO replies, except for your second comment to yourself...
... I am the first person to reply here 🙄
@@johncoops6897 I'm sorry but I counted 7 or eight, not including my replies to those that addressed me.
Excellent video and great graphics. I'm impressed. Thanks for making it.
Very thorough explanation of the build.
Brilliant video and graphics for any budding young electrical engineer.
Wish my early days electrical engineering lecturer had had the same skills as you have...some 60 years ago.
Thanks for the brilliant technical description.
As below wonder what I would do with this power supply?
Thanks for the video, looking forward to more of the same.
Wow so many great comments here and yes this is brilliantly presented, thank you and looking forward to more great content.
What an excellent presentation. Very professional, and very informative.
This the best video ever about microwave operation. Thank you.
I was confused for a while since I've always used a straight line and an arc line to represent a capacitor and 2 straight lines in parallel to present a contact points after you explained it I caught on, great job at instructing
Yikes! That would make you the only one in the world that uses such a symbol, which is unsafe! There is an international standard:
- The two parallel lines is ALWAYS a capacitor, and it is used when the capacitor can survive being charged in BOTH directions.
- The one straight and one arc line is ALSO a capacitor, but a special sub-type that can ONLY survive being charged in ONE direction.
- A contact point is A SWITCH and such are ALWAYS drawn with a conductor-line that is broken at an angle, such that if the angle is straightened out the whole component just becomes a straight line.
Ditto on the last comment. Definitely a top tier presentation. Thank you very much. ⭐️⭐️⭐️⭐️
Thank you. I think you explained this quite well and still accurate while leaving out a few more technical physics matters. It is interesting how often these units are often thrown away while there are components that still have many years of life left. Thank you for your video. I am going to build this and maybe add a voltage doubler to have a nice gas laser power supply.
Very good presentation, images and communication made the video outstanding.
I love the amount of information and extensive education in basic electricity. Great video, thank you for the upload.
Although, this video is extraordinary in it's information and instructions I fear it is lost on 95% of those watching it as they don't want the how and why's of the project, they want the black and white, "put this there and that's there" mindless instructions. Society today has been groomed for zombification and care nothing for the education over instant gratification. Sadly.
I've added a new word to my lexicon: zombification.
i wish you were instructor in my navy electronics school. well explained!
Excelent !!!!!
Clear. Complete, practical , concise.
As stated, he did a great job of going through all of the math, and explaining everything, how ever you seriously scrued up on the output, as you mentioned it is a doubler, and if you were using a supply transformer with a floating secondary, you could call the output "0 & 6,000 volts, but that is not what you have. Because the transformer secondary is one end grounded, the output is actually two 3100 volt half wave supplies in series, which is a plus and minus 3100 volts to chassis, so by labeling the one side 0 volts and the other 6,000 you have given a false representation of what is actually present, and if someone builds this Supply and connects the 0 volt side of the power supply to the chassis of there project, it will cause the power supply chassis to be + 3100 volts above the chassis of there project. And I can tell from your explanation of the build that you are smart enough to know how dangerous this could be. I'm sure it was just an oversight, but a dangerous one at this voltage level, as you mentioned, it's well inside the lethal range, so please correct this on your video before there is a tragic accident!!!
No, it is as he stated. What we have here is a one stage voltage doubler. So 6000 V.
Oops! I just noticed that your schematic indicates that your metal enclosure is not grounded! That's an industry standard *No - No!* Metal cases MUST be grounded when connecting to mains. As it stands now lethal voltages are present between the Zero and 6000 volt terminals and the Zero Terminal and the Transformer Core and any metal making contact with the Core. If I'm wrong, please correct me.
The schematic might lack it but it's present in the actual supply - th-cam.com/video/OBQTBgFjFsQ/w-d-xo.html
At 6:00 he grounds it but he grounds it to the same transformer ... ain't you supposed to ground it to EARTH ?? PLS RESPOND
@@PORTEnSious It finds Earth Ground through the green conductor in power cable.
Wakodahatchee Chris
Just in case someone still wonders about the ground. The metal case is grounded by the green wire connecting the middle prong of the power supply cable and the metal case seem at 25:27 in the video. So you would need to use good 3 prong power supply cable on a proper 3-prong grounded outlet. The author mentioned he used a computer power supply cable for it.
What are you talking about about he explains with incredible detail.
Very informative. You should be a teacher. You are great at conveying your knowledge...
You have a great narrative voice.
Great sir highly apprciated and greatceffort and well scoped video and very very well elaborated for every single person hope to see your farther videos
This video is insanely well made, good job!
Very meticulous,comprehensive explanation👍...It's like when I'm explaining for my buddy the repair of his guitar amp,he is about to go haywire🤣....but I don't go to this much details.Well I'm having fun of course😀
i just watched this whole video and i dont really know anything about electrical engineering but this is cool
Very nice step by step explanation.
Oh yeah, FEMALE output connectors would eliminate a SERIOUS shock / short accident...which will happen sooner or later in this front panel design!
THANKS AGAIN FOR THE GREAT VIDEO!!
Very good explanation and Safety Tips. I just wish I'd seen it a few years ago before I blew up my expensive Fluke meter.
This is the best explain i ever heard.❤
What an analysis. A whole course to someone like me, done in style.
nice informing and detailed information and calculations -- very professional!!! thx a lot
Good, educational video, but people, pleaae learn the AC/DC rectification fundamentals on low voltage.
I advise against building this particular arrangement. The primary winding on the transformer is NOT designed to work on floating 3kV level. It works only because a well built transformer uses huge safety margins (and required to be HiPot tested). Look at how much insulation is on the secondary side and almost none on the primary!
Several aspects of the mechanical build is also a major safety issue.
You do NOT use wing nuts and bare metal connectors on 230V even, let alone at 6kV. The output terminals should be insulated and a connector rated for at least 6kV continuous use should be used.
There should be a visual indication that the output voltage is present on the terminals. Ideally it should continuosly indicate as long as the voltage is still above 50V (!), even when the primary is switched off already.
There should be some sort of interlock which is, when not enabled, does not allow switching on the output.
HV capacitors and test circuit outputs are usually required to be SHORTED to each other and to earth when not enabled, otherwise it is UNSAFE to touch.
On typical proper lab testing systems one level of interlock on the safety enclosure is responsible for shorting the outputs and a second level to enable the HV power.
This seems ridiculosly complicated and inconvenient but the energy and voltage at these levels can kill you instantly.
Like PhotonicInduction said:
You will be dead before you hit the floor.
Every so often while watching this "but trust me on the sunscreen" went through my head.
Very cool teacher.
..big Buda boom..in there..
Be careful.
Great instructional video you have here. I like it. Your description of the oscilloscope is very good. Could you do an O-Scope video on operating a Scope from a newbies point of view, please? I would like to see what yo come up with!
Very precise presentation .. thank you !!
Very informative. Tore the heck outta many discarded units and ended up with a few heavy ass milk crates full of M.O.T.'s
Yikes! I'd be nervous working with a HV PS that has a metal chassis and metal wing nuts, even if I built it. I would want an internal metal chassis but an external plastic or wood case. Large banana jacks for the the connections and a plastic switch for on/off. Still you have to be mighty careful working with the output!
NICE video. I like to see video's that are well presented full of accurate scientific information, and concise and useful. Excellent.
I really appreciated this video. Unlike some guys on TH-cam who endanger themselves and others you clearly know what you're doing. Also, got to love a Tek 475!
Excellent description of the circuits. Great job. I work with high power high voltage daily in my job. I like this project very much and don't want to see anyone injured and that pain placed on you. As well as possible legal liability.
So, please let me share a few critical observations.
1. This IS NOT a project for beginners. Period.
2. The meter you are using at the 30:00 minute mark is either 20K/volt or, worse yet, 1K/volt. That will present a 20K ohm load in parallel with your sense resistor giving an inaccurate reading. Take this resistance into consideration as well. I calculate this to be 952.3 ohms for the total sense resistance.
3. The output terminals on this supply are outright criminal. The relief openings behind the bolts are FAR TOO SMALL for safety. Please find some proper recessed high voltage terminals and matching plugs. It is far too easy to contact these terminals and DIE INSTANTLY.
4. Go to the automotive parts store and purchase spark plug wire, 20KV break down at a minimum, for your leads. I use 40KV rated wire on my 6KV supply here in my home lab.
5. You should bring out the ground and then relabel the out put terminals "+3000V" and "-3000V", labeling the ground "0V". This gives the option of a grounded 3KV supply ("safer") or a floating 6KV supply by ignoring the ground (0V) terminal.
7. If you place a variac transformer on the primary side of the HV transformer, you now have a zero to full voltage high voltage power supply. My commercial HV supply (Leybold) does exactly this.
LAST COMMENT. You can see how I use my commercial high voltage power supply in my video entitled, "PhiloCam Part 16 - Power supply problem proven beyond a doubt".
No comment how he has the frame of the Microwave Oven Transformer floating, and mounted on G10/FR4 board material?
12:37 for those who are curious about the number 0.707 which is the result of calculating Vpeak -> Vrms
Vpeak*sqrt(1/2)=Vrms => Vpeak*1/sqrt(2)=Vrms
both, sqrt(1/2) and 1/sqrt(2) ≈ 0.707 (well, 0.70710678… to be precise-ish) (sqrt(2)≈1.414 -> 1/1.414≈0.707)
In the end, Vpeak/sqrt(2)=Vrms
THANKS FOR THE GREAT VIDEO!!!
As an upgrade, you could put another capacitor in parallel with EACH of the existing two for more smoothing (two more caps). A volt meter using a voltage divider for calibration would be nice (maybe one for current also...this one would be easy to use as-is). A VARIAC at the AC input would make a great 'variable' DC supply.
WARNING: Be aware that the variac can step the input above 120VAC!
The only thing that bothers me is the voltage rating of the caps...close...espically if variac driven at the higher voltage region.
Very Nice Video well informative THNX
Good Sir - I used your tutorial - it is one of the best on TH-cam. Thanks! It worked perfectly. Now I have two questions, but first some background. - I wanted to throttle down the output voltage so I put a variac on the AC input. This worked very well when all I had on it was a volt meter. My project also calls for pulsing the high voltage. I am currently doing that with two solid state relays. One to connect the positive output to the load and the other to connect the negative output to the load. They pulse at exactly the same rate and are driven by the same driver - both on and both off at the same time. they are being pulsed on for about 50 millisec out of 110ms cycle time. I have to isolate the ground for my project.
When I turned on the variac with only a minimal load with the outputs of the power supply hooked to the load through the pulsing relays, the variac started buzzing and then a wisp of smoke! I shut it down immediately. The variac has a 20 amp fuse but it did not blow. After my hands stopped shaking I removed the pulse, hooked it up to a voltmeter, and it worked just like before. Now for my questions -
1 Why would this happen?
2. Would it likely work if I pulsed the input to the variac instead of the DC output from the power supply?
Thanks!
Mark Cooper
Every time you disconnect the transformer, it produces a MASSIVE spike of high voltage high current "Back EMF" through the primary winding. This will often damage the solid state relays and is probably being passed back to the variac. Furthermore, there is a huge inrush current proportional to the point in the mains waveform when the power is applied.
A microwave transformer is not designed for pulsed operation, but to run continuously for seconds or miinutes at a time. The control circuits of the microwave will have some small protection for the switching relay, to ensure that it doesn't arc too much. But these are nowhere need strong enough to protect against switching at about 10Hz that you are trying to do.
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The bottom line is that you should use a transformer that's designed for pulsed operation, for example an automotive spark plug coil. To make your existing circuit work you need to add some seriously heavy duty protection against Back EMF on the primary side, and that will be complicated by the fairly high switching frequency.
Adding to my previous comment... if you are actually trying to run the transformer continuously the use Solid State relays to switch the ~5KV outputs...
... that cannot work, as the SSR's will almost certainly not be rated to handle that kind of voltage.
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The SSR's are probably flashing over and creating a dead short circuit on the output side, or have already been completely fried.
.
The fuse on the cardiac will only blow at several times greater than it's rated Current. So the fact that it didn't blow doesn't mean that you weren't pulling >20A from it. If the load is pulsed then you might need to be pulling 100A at 50% duty cycle before that 20A fuse will open. In the meantime, the carbon brush is dying anyway, probably causing the smoke you saw.
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BTW I overloaded my variac quite badly when trying to run it with small normal transformers wired "backwards" to create higher output voltages. There is something about the load profile of the transformer windings that creates an excessive current draw, even with no load applied to the output of my step up transformer.
I think you need to explain that anyone building this or messing with a microwave does so at their own risk !! You did say these voltages can be fatal, Im adding also cause terrible burns. I'm somewhat puzzled why anyone needs such a high voltage power supply. The only purpose I can think of is an RF linear amplifier. I shudder to think of an inexperienced person attempting to build this power supply or even attempting to probe these voltages. These voltages can jump gaps, and if you dont understand, please stay clear of this project. It will kill you !! I hope nobody is injured or killed after trying to duplicate this project. It is very dangerous !!
woow week of lesson i taught in electronic class in course i reminded from this video within few minutes
Thanks, for the great value, well set out,very clear and consice really appreciate a different perspective,a much more truer depiction, of current flow schematics 🧐✅🏆,
I fear these instructions will enable incompetent people to build something that is very damn dangerous! This thing can and will KILL YOU! I don't know the extent of liability for which you would be held accountable, but this is not something an untrained individual should be fooling with.,.. I sure hope no one gets killed.
Hi there and thanks for the upload, very informative but (as others have already said) as a professional EE, I must raise major safety concerns for any inexperienced or careless person who might try to copy your work. With the suggested wing-nut connectors and gardening gloves, and no power warning light, this is probably the most dangerous project I have seen recently. Please don't build anything like this if you have ANY doubts, and do watch my video about safety aspects of using microwave oven transformers. At least one person has been killed by a MOT.
On the technical side, the transformer waveform is badly distorted because the core is heavily into saturation due to the cost-cutting with short windings and a narrow magnetic path. This saturation causes the transformer to pull more current and heat up even on no load. If you are stripping two microwaves, you can solve this by running two transformers, with the primaries in series and the secondaries in series, with the transformer cores joined to form a centre-tap which could be grounded through a high-voltage resistor for a slight safety improvement.
How is it I have I not found you, until now?
You have left no questions unanswered!
Nice work! New subscriber!👍🇺🇸
Fantastic, thank you so much for sharing your wealth of knowledge.
If you want to get a little more current out of it, remove the magnetic shunts from the transformer. There should be two little metal wedges stuck between the primary and secondary windings.
28:10 "of course, there's a risk of shock" - a wee bit of an understatement. 10 mA going through a flexor muscle will prevent its relaxation - grab that wire and somehow complete the circuit and you won't be able to drop it.
An indicator light to know it's powered and some bleeding resistors across those capacitors would be good to have.
i’m not qualified to say this is a perfect video. but it’s refreshing to not hear distracting “music” or other ambient sounds, useless stuttering n suffixes n prefixes like um, ah, nnn boring us. clear pictures is really pleasing. u sound like my brother, an EEE. or r u an audiobook reader with that pleasant voice n good delivery? being a jack-of-all-trades, this wuzn’t totally satisfying 4 me. i’d preferd the last 15 minutes b used 2 show me the potential of this creation. :o)))
Excellent delivery