It is a rating for unrectified AC voltage. The 450V AC rectified is almost equal to the 650V DC rating. There also are AC caps, which will stay at the voltage level they had in the moment they were unplugged and can also reach the rectified voltage. Technically their voltage can even exceed the AC voltage peak, if there is also an inductor, which discharges it's energy into the cap.
@@IMSAIGuy Try preconditioning the screwdriver first on smaller low voltage caps. If you convert the screwdriver tip into a carbon resistor it will discharge the large caps more slowly!
I screwed an expensive audio amp when I opened the lid and my screwdriver accidentally hit a big cap. I didn't care about the screwdriver but after that I had to listen to a hummingbird singing along with my speakers.
I think you should build one using an arduino to control the discharge. Make it really complicated! Be sure to have it WIFI capable too! Otherwise use a 50 ohm 5 watt resistor and be done with it!
Might want to use an ESP32 as Arduinos don't have the power to update high res displays at 30+ fps. plus you'd need both Bluetooth and WiFi. You could pulse the shorting resistor while monitoring it's temperature while displaying remaining voltage plus an estimate of how long it will take to reach zero.
Don't forget to add two factor authentication and send usage statistics to Google cloud services so it can be then analyzed and appropriate ad be displayed in the middle of discharging.
That would have been useful a few months ago when I was working on a switching power supply. I was discharging the big capacitor on the primary side through a resistor attached to a pair of clip leads. It worked great except for the one time that I forgot to disconnect power before discharging the capacitor. It was spectacular! After the fireworks display, I was left with a rectangular pit in my workbench (i.e. my dining room table) with black scorch marks all around it. Fortunately, the table was one of those rustic slab tables, so I was able to convince my wife that the damage looked like a natural flaw in the wood.
looks like zener 4.7 or 5.1v. So mosfet 2n100 has less than 0.7A current flow at this gate voltage. And 1D transistor with 7.5R shunt resistor limits mosfet at 0.6v/7.5R = 80mA.
Seems a bit complicated when a simple resistor will do the job. Of course you'll need different values for discharging a CRT at kV vs a tube circuit at just 100s of volts. Also never forget that capacitors will regain voltage after you discharged them, so you will want to short them with a wire after discharging to keep the voltage at zero.
They do eventually self-discharge to a few volts, to nothing.... but, the big ones might take some time. And it's the high voltage ones that need to be respected...if one doesn't want to die.
I got one, but it only discharged our 820kF capacitor down to 3.9V. A tragic crowbar disaster ensued. Though no digits were lost, a very exuberant "YIKES!" was had. a new crowbar is in the budget.
looks like just another death trap! rated up to 650V with one layer of heat shrink over some of the tracks. the probes exposed. etc. Good job they got it checked by UL for safety, they did didn't they. 🙂
Not sure if Uncle Kim Cuck Augustus here in the uk! They said they have not see it, but feel anyone using it on 650V may not be able to complain in person so its OK 🙂 @@IMSAIGuy
This thingy will blow up rather quickly when you really connect it to 450VAC as the MOSFET will have to dissipate >30W. The advantage of such a circuit over a resistor is that you can use it over a huge voltage range and you have an indicator that clearly tells you when the cap is discharged. I made a similar tool for work as we had to discharge 200V electrolytics. I put a PTC in the current sense to prevent thermal destruction in case of abuse.
Voltmeters also leak... more than capacitors. 12V/200k=60uA collector current needs only Vb=0.4-0.5 V. Plus, the collector and drain also leaks. I doubt whether the current source had reached its constant current region.
I kinda like it, especially the pins. Looks much easier to get a good connection with than the flimsy leads of most resistors. And the LED gives you a discharge indication. I mean, I have just used a resistor up until now, but this thing is tempting...
@@Agent24Electronics add a circuit with an LED to the resistance and you have an indication too, that's how my discharger works (described in a separate comment)
I just stumbled across one, too. But it seems you are missing diode D4 in your schematics - is it just not relevant for the circuit? I noticed, because mine has a fancy Zener diode there and then re-viewed your video. Your variant seems to have a black diode there, but could still be a Zener, too. Could it be to protect the gate of the FET?
If its anything below 5,000 microfarad, I'll short it with the needlenose pliers. Above 5,000 mF, I'll stick the voltmeter across the cap; usually the bleeder will pull it down to a safe level in under a minute, then I'll short it. But hey, I'm just a hairy hand knuckle draggin' mouth breather. This looks like something Mr. Carlson would design. He's a smart guy, but he is realllly pedantic.
Pedantic is the price he pays, not what we pay. With a gift like that, he has a well worn groove for explaining over and over until the light comes on for the rest of us..arguably..too worn. Gifted people are more about understanding the convoluted rules of disciplines that confound the rest of us on basic approach. In that sense the repeats are because half his audience are 30 IQ points behind YOU. Just saying.
The real test would be to discharge a CRT anode. What part on that device makes smoke first? I've only had to do that once or twice when working on my Heathkit H-19 terminal, and it was always an exciting process.
Was your hp power supply limited to 20ma as the current dial is turned down, maybe if it was turned more to the right it would display the correct current draw of the discharger.
Hi, Just put your great meter U1272A into first mode from left. It is called "ZlowV" voltage measurement. Done! For everyone else who doesnt have this, yep, looks intersting ;) PS. Same you can find in Fluke 289; it is called LoZ.
I've always just used an old screwdriver (has lots of black spots on it). In my 60 some years of fiddling with electrons, never occurred to me to use some fancy cap discharge thingy.
@@scrook1027 just a rough estimation: energy in a CRT ~mJ, energy in a decent capacitor ~J Had been working in a TV workshop back in the days and never been afraid of discharging CRTs
What's the transistor that's in it can you tell us or does it really matter what type? I think I see a SOT PACKAGE "1D" a 300v npn . Is that right??? And it uses a 1000v fet. (From my quick check on them) 😊😊😊😊
@7:30 "We're Done" - Really?!? Still has voltage. With all those diodes, there will be residual. If I subsequently attach it to a LCR meter I could still damage it.
Nice Toy :-) for this Price, in the Video Called "SOLUTRONIC High Voltage Capacitor Discharger", I reversed Engineered a Professionally HV Capacitor Discharger, made for Internal use in the Factory of a Large German Inverter Manufacturer !
Hi, the discharger has one advantage and that is the size, my discharger is a 4x6x3 cm box with classic 4mm connectors and I can connect spikes, clips, or connect to another test fixture for automatic discharge of capacitors. Discharger assembled from resistors, but I added a two-color LED so I can see the polarity in the discharged circuit (if it is on the red socket + the LED lights up red and - green) with a fixed connection, you can switch a small switch after the LED goes out and the terminals are shorted (just don't forget switch back before the next measurement). I've been using it for years without the slightest problem, built from scraps. Nice day 🙂 Tom
Your discharger doesn't have the disadvantage of burning a hole in your finger if a piece of heatshrink breaks down though. There's no way I would trust a single layer of the cheapest Chinese heatshrink to protect me from a big 400V cap.
@@rocketman221projects You're right, the wall of the box is 4mm, the only downside is the switch, originally I had a lever switch with automatic return, but then I changed it to a classic switch so that I don't have to hold it in case I need to get rid of the capacitors' back absorption. It is tested at 650V DC, that is the maximum voltage of my capacitor DC leakage meter (the meter can discharge the capacitor by itself after the test is finished). Nice day 🙂 Tom
![[Full Episode] MasterChef Junior Thailand มาสเตอร์เชฟ จูเนียร์ ประเทศไทย Season 3 Episode 3](http://i.ytimg.com/vi/A1XXYbV048k/mqdefault.jpg)
Oh... it's for AC capacitors too! I didn't know that caps can store AC 🙂
Must be those cheap Chinese capacitors LOL
They not store ac only dc!
🤣
@@felipehcraftgamer4193 Really...??? Oh man! If I only knew that before...
PS: You missed the joke! 🙂
It is a rating for unrectified AC voltage. The 450V AC rectified is almost equal to the 650V DC rating. There also are AC caps, which will stay at the voltage level they had in the moment they were unplugged and can also reach the rectified voltage. Technically their voltage can even exceed the AC voltage peak, if there is also an inductor, which discharges it's energy into the cap.
I miss the good 'ol days of just shorting the leads with a screwdriver.
I've welded a few screwdrivers to caps
@@IMSAIGuy Try preconditioning the screwdriver first on smaller low voltage caps. If you convert the screwdriver tip into a carbon resistor it will discharge the large caps more slowly!
I use a 50 ohm resistor for high voltage caps
I screwed an expensive audio amp when I opened the lid and my screwdriver accidentally hit a big cap. I didn't care about the screwdriver but after that I had to listen to a hummingbird singing along with my speakers.
Hmm, reminds me of high school electronics shop - charging a cap up and leaving it on the workbench. ;-)
I think you should build one using an arduino to control the discharge. Make it really complicated! Be sure to have it WIFI capable too! Otherwise use a 50 ohm 5 watt resistor and be done with it!
Obviously it would need a full color OLED display and GPS.
@@TheDigitalAuraSince it's IOT enabled, it should require that it phones home once a month to verify your subscription!
Might want to use an ESP32 as Arduinos don't have the power to update high res displays at 30+ fps. plus you'd need both Bluetooth and WiFi. You could pulse the shorting resistor while monitoring it's temperature while displaying remaining voltage plus an estimate of how long it will take to reach zero.
My sentiments exactly 😂
Don't forget to add two factor authentication and send usage statistics to Google cloud services so it can be then analyzed and appropriate ad be displayed in the middle of discharging.
That would have been useful a few months ago when I was working on a switching power supply. I was discharging the big capacitor on the primary side through a resistor attached to a pair of clip leads. It worked great except for the one time that I forgot to disconnect power before discharging the capacitor. It was spectacular! After the fireworks display, I was left with a rectangular pit in my workbench (i.e. my dining room table) with black scorch marks all around it. Fortunately, the table was one of those rustic slab tables, so I was able to convince my wife that the damage looked like a natural flaw in the wood.
Great video! Thanks for sharing, just what I need to step my discharge game!
Any possibility you missed diode D4 on your schematic? My guess would be a zener to prevent excessive gate voltage.
looks like zener 4.7 or 5.1v. So mosfet 2n100 has less than 0.7A current flow at this gate voltage. And 1D transistor with 7.5R shunt resistor limits mosfet at 0.6v/7.5R = 80mA.
Seems a bit complicated when a simple resistor will do the job. Of course you'll need different values for discharging a CRT at kV vs a tube circuit at just 100s of volts. Also never forget that capacitors will regain voltage after you discharged them, so you will want to short them with a wire after discharging to keep the voltage at zero.
Is there a way to contact you outside of TH-cam? I'd like to discuss/provide some feedback for the analyzer suite. You graves us with.
They do eventually self-discharge to a few volts, to nothing.... but, the big ones might take some time. And it's the high voltage ones that need to be respected...if one doesn't want to die.
I got one, but it only discharged our 820kF capacitor down to 3.9V. A tragic crowbar disaster ensued. Though no digits were lost, a very exuberant "YIKES!" was had. a new crowbar is in the budget.
The comments here did not disappoint, all that electrified testosterone 🤣🤣🤣
Nothing better than a 230V, 5W light bulb. It's so scary when it lights longer than 2 seconds.
or 3 lamps 230v in series for VFD power bus 540v with inrush current limiting detail: 10-20R resistor or some PTC/NTC.
looks like just another death trap! rated up to 650V with one layer of heat shrink over some of the tracks. the probes exposed. etc. Good job they got it checked by UL for safety, they did didn't they. 🙂
Uncle Larry said he liked the shape and approves 😂
Not sure if Uncle Kim Cuck Augustus here in the uk! They said they have not see it, but feel anyone using it on 650V may not be able to complain in person so its OK 🙂 @@IMSAIGuy
@@IMSAIGuy Does Uncle Larry live in Huaqiangbei Shenzhen?
This thingy will blow up rather quickly when you really connect it to 450VAC as the MOSFET will have to dissipate >30W.
The advantage of such a circuit over a resistor is that you can use it over a huge voltage range and you have an indicator that clearly tells you when the cap is discharged.
I made a similar tool for work as we had to discharge 200V electrolytics.
I put a PTC in the current sense to prevent thermal destruction in case of abuse.
what's wrong with good old incandescent lamp?
@@Mr.Leeroy Absolutely nothing except it’s too low-tech
@@inse001 add PTC (:
multiple in series to be as high-tech as you desire
Voltmeters also leak... more than capacitors. 12V/200k=60uA collector current needs only Vb=0.4-0.5 V. Plus, the collector and drain also leaks. I doubt whether the current source had reached its constant current region.
I do use an old bulb 220v 60w it is so simple but it is an easy way to check the full discharge
But yours it is fun to do
Good day to you
This thing is absolutely over the top. A simple resistor always served its purpose.
I kinda like it, especially the pins. Looks much easier to get a good connection with than the flimsy leads of most resistors. And the LED gives you a discharge indication. I mean, I have just used a resistor up until now, but this thing is tempting...
@@Agent24Electronics add a circuit with an LED to the resistance and you have an indication too, that's how my discharger works (described in a separate comment)
@@Agent24Electronicswhen the indicator goes out there is still charge left. Need a resistor to finish the discharge to zero anyway.
Try safely discharging a 2700uF with 400V on it. Not really that simple any more.
@@joshadler7209 Yep. Built a few ceramic resistor jumpers to do it safely and reliably.
yeah more amazing book sir
What's your current limit set at on supply ?
Cool! May not be necessary, but I'm getting one anyway 😀
Meh. You can't even use it as a screwdriver.
I just stumbled across one, too. But it seems you are missing diode D4 in your schematics - is it just not relevant for the circuit? I noticed, because mine has a fancy Zener diode there and then re-viewed your video. Your variant seems to have a black diode there, but could still be a Zener, too. Could it be to protect the gate of the FET?
If its anything below 5,000 microfarad, I'll short it with the needlenose pliers. Above 5,000 mF, I'll stick the voltmeter across the cap; usually the bleeder will pull it down to a safe level in under a minute, then I'll short it. But hey, I'm just a hairy hand knuckle draggin' mouth breather. This looks like something Mr. Carlson would design. He's a smart guy, but he is realllly pedantic.
he did make a cap bleeder. for his patreons only of course. way over kill with large resistors.
Pedantic is the price he pays, not what we pay. With a gift like that, he has a well worn groove for explaining over and over until the light comes on for the rest of us..arguably..too worn. Gifted people are more about understanding the convoluted rules of disciplines that confound the rest of us on basic approach. In that sense the repeats are because half his audience are 30 IQ points behind YOU. Just saying.
Your videos are so great, these days I click the "Like" button before the video even starts
The real test would be to discharge a CRT anode. What part on that device makes smoke first? I've only had to do that once or twice when working on my Heathkit H-19 terminal, and it was always an exciting process.
Was your hp power supply limited to 20ma as the current dial is turned down, maybe if it was turned more to the right it would display the correct current draw of the discharger.
This item is actually cheaper than a 50 ohm metal ohmite 10w resistor from say digikey..how do the chicoms do it ?
Maybe 20ma on the hp because the cc limit control is not turned full cw
Hi, Just put your great meter U1272A into first mode from left. It is called "ZlowV" voltage measurement. Done! For everyone else who doesnt have this, yep, looks intersting ;) PS. Same you can find in Fluke 289; it is called LoZ.
Unless your capacitor is storing more than a few joules, then don't do this, unless it is time for a new great meter.
Old school screwdriver is a lot more fun .
Why? I just short hv caps. If it pops, need to find a the bad bleeder R.
Cool‼
I've always just used an old screwdriver (has lots of black spots on it).
In my 60 some years of fiddling with electrons, never occurred to me to use some fancy cap discharge thingy.
Electrolytics charged to 400V in PFC stages are not funny to short with a screwdriver
@@inse001 Probably no worse than the anode on a large CRT. Some give off a really loud bang!
@@scrook1027 just a rough estimation: energy in a CRT ~mJ, energy in a decent capacitor ~J
Had been working in a TV workshop back in the days and never been afraid of discharging CRTs
What's the transistor that's in it can you tell us or does it really matter what type? I think I see a SOT PACKAGE "1D" a 300v npn . Is that right??? And it uses a 1000v fet. (From my quick check on them) 😊😊😊😊
MOSFET
I'm going to make one 😊😊😊
I have survived 55+ years of electronics endeavors without one of these, just saying.
I agree.
your schematic circuit D4 diode missing
@7:30 "We're Done" - Really?!? Still has voltage. With all those diodes, there will be residual. If I subsequently attach it to a LCR meter I could still damage it.
i use an fridge bulb with 2 legs.
I wonder if one of those Gizmos can discharge my 3300 volt 1 amp Linear Power Amplifier power supply😊
I want to be in the back of the room watching when you try 😎
Thank you for the video. Do you have a link for that product on AliExpress?
Add the word “switch” in your search
I have some 3000F super capacitors not sure the discharging pen would survive.
it is current limited so yes, it should be fine
What voltage?
@@IMSAIGuy
But I will have to hold it in place for 125hours to discharge the the 3000F super capacitor.
@@inse001
3V
@@inse001
3V T=(VC)/I
Nice Toy :-) for this Price, in the Video Called "SOLUTRONIC High Voltage Capacitor Discharger", I reversed Engineered a Professionally HV Capacitor Discharger, made for Internal use in the Factory of a Large German Inverter Manufacturer !
Ohh, yeah. I hate it when there is still some residual AC voltage left in the cap.
but you do have to buy the correct AC cap's for that to occur. 🙂 normal one just get left in the last charged polarity.
That is what the diode bridge is for. To convert it to DC before it discharges😉.
How do you store AC in a cap????
Ancient Chinese Secret
@@pvc988 Honey, we need more Calgon!
For AC you need flux capacitor
You need to visit Shenzhen, and pay, to learn secret. (Not everything free.)
The process is similar to generating single pole magnets
Hi, the discharger has one advantage and that is the size, my discharger is a 4x6x3 cm box with classic 4mm connectors and I can connect spikes, clips, or connect to another test fixture for automatic discharge of capacitors. Discharger assembled from resistors, but I added a two-color LED so I can see the polarity in the discharged circuit (if it is on the red socket + the LED lights up red and - green) with a fixed connection, you can switch a small switch after the LED goes out and the terminals are shorted (just don't forget switch back before the next measurement). I've been using it for years without the slightest problem, built from scraps.
Nice day 🙂 Tom
Your discharger doesn't have the disadvantage of burning a hole in your finger if a piece of heatshrink breaks down though.
There's no way I would trust a single layer of the cheapest Chinese heatshrink to protect me from a big 400V cap.
@@rocketman221projects You're right, the wall of the box is 4mm, the only downside is the switch, originally I had a lever switch with automatic return, but then I changed it to a classic switch so that I don't have to hold it in case I need to get rid of the capacitors' back absorption. It is tested at 650V DC, that is the maximum voltage of my capacitor DC leakage meter (the meter can discharge the capacitor by itself after the test is finished).
Nice day 🙂 Tom
A 10-20 ohm resistor is much easier
Just lick it ¯\_(ツ)_/¯
I use 56k 10W resistors, as i have a lot of them, and no bang when the capacitor is charged to 400VDC either.
That’ll be a spicy “safety procedure” when I hit the 400-600V caps in my tube amp…
Interesting circuit, but I don't see any use for it.
I had this thing. It is a piece of shit. Exploded on me 😄There are WAY better versions on ali with normal leads and a voltmeter.
That's useful.
EDIT : Just ordered one, £4.25 free shipping. 👍
I can only find them for €16,05 and up. What is the item id (in the url?) I found this one: item/1005002664085092
IMO, ridiculous. (Alibaba below average trash... with the usual disregard for human life.)
th-cam.com/video/IpdjCZ-21o0/w-d-xo.html