Assembling The Capacitor Discharge Device, Schematic's Included.
Added 2018-02-15 23:14:20 +0000 UTCHere is the build process for the capacitor discharge device, with circuit explanation. See how it performs as I discharge a large capacitor. Do you think we should design a "smart discharger" together? (see the video for more details) Let me know your thoughts in the comments below.
Patreon NEW LIST of Videos: https://www.patreon.com/posts/8239565
This is video #38, include this when requesting attachments.
Schematic winners are:
#1 Winner: Yannick Turcotte.
#2 Runner up: John.
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Schematic attached below.
Comments
The schematic.pdf file link doesn't seem to be working, do you know anyway I can get the original pdf file?
Rick Serafini
2025-01-25 02:35:17 +0000 UTCI have assembled the capacitor discharger and am getting 4K Ohms on the meter. Also, when I short the probes together the resistance goes close to 0 Ohms, When I measure voltage across a 9V battery I get 9 Volts on the meter, however the LEDs do not light. Could I have switched the polarity of the Zener diodes? I connected the LEDs in series with a resistor and confirmed that they are working properly.
Brian
2024-08-01 23:21:02 +0000 UTCI ended up buying a set of probes with much thicker gage wire - here is the link https://a.co/d/6vjh7ur
Brian
2024-08-01 22:58:00 +0000 UTCThere is not much curent going through any of the circuit. The 4K resistors see most of the current and even they only pass up to 600/4000 = 0.15amps. I used 18ga wire, but even that is overkill from a current perspective.
Brian
2024-08-01 22:55:58 +0000 UTCDigikey part number 1722-1299-ND worked for me. You have to drill a hole that is just smaller than the outer diameter of the grommets.
Brian
2024-08-01 22:53:15 +0000 UTCIt is designed to discharge any capacitor up to 600V.
Brian
2024-08-01 22:51:49 +0000 UTCI recently purchased the supplies to build this discharger. I ordered two sets of probes from Amazon that were apparently rated at 1000V, 20A. Then I realized that I don't actually need two sets, since I can cut the probes in half- using the one half to go to the multimeter and the other half to use the probe tips. When I cut the probe wires (toward the end with the multimeter plugs) I found the copper wires to be extremely thin. I would estimate them to be 22Ga. at best. I say this to caution people that there are products out there being marketed as 20A that are NOT 20A, and also to ask if anyone has a recommendation for probes that they know can handle 20A!
Brian
2024-07-29 22:42:52 +0000 UTCI'm still learning how to read schematics, but I I wish we had pictures showing more detail. I can't quite see how things are connect in the video, and confused about some thing, it looks like you cut the terminals off some of the large resistors for instance. If anyone has any step by step pictures and layouts please let me know. I know I should understand the schematics better, but I'm a visual learner, so seeing how everything is connected helps me understand schematics better too.
Devin82m
2024-05-14 00:26:14 +0000 UTCHi Paul really great video can I ask what gauge/size wire did you use to connect up your resistors and what type of insulation is on the wire. From the video it looks like a white fabric? I'm very new to this so a very basic question I know?
William Wolf
2023-12-04 08:28:21 +0000 UTCCold you also design it with a volt meter built into the box so one would not have to connect a multimeter?
John E Barron III
2023-11-22 15:23:47 +0000 UTCJust go to Home depot and pick up some grommets.
blacklistedcard
2023-08-15 03:56:20 +0000 UTCCan anyone provide a digikey part number for the cable "grommet-like" things that mount on the case and provide strain relief for the probe cables?
Chris Kniker
2023-02-01 18:22:03 +0000 UTCThank You, Awesome Work
LoSaYa
2022-10-18 21:32:50 +0000 UTCIs this capacitor discharger suitable for the 50uF 350v filter caps in valve radios, or is a mod required to make it more compatible?
Kevin Richardson
2022-04-29 09:22:51 +0000 UTCHi, did Paul ever say what brand of glue he was using? I would like to order some, I currently use gorilla super glue.
Andy, KB1UIF.
2022-04-21 03:29:50 +0000 UTCIs the length of the leads arbitrary? If so, would using one pair cut in half work as long as I'm comfortable with the setup?
Ross Hollinger
2021-12-16 02:22:01 +0000 UTCYeah I'm curious what the glue was
Ru Kojo Lemer
2021-10-07 23:20:39 +0000 UTCDid the smart version ever make it into a video ?
Hans Engelen
2021-08-29 09:49:28 +0000 UTCPaul, either you never mentioned your super glue or I just missed it. TKX
Jim MacLean
2021-08-21 17:26:40 +0000 UTCHey Paul, what ever happened to the idea of making this a smart discharger? Also, I was wondering if for now on you can include a PCB file for any projects you present that require a circuit board to be made, that way those of us who don't feel comfortable making our own can send it off to a PCB maker to get a few printed for us. Thanks!
Devin82m
2021-03-26 16:56:23 +0000 UTCI wonder if this would also be suitable to discharge a CRT, or if 24kV will blow up the LED circuit...
aletux
2021-03-17 23:35:05 +0000 UTCHi Paul, completed this project today as my first ever electronics project. First 2 tests fine, 4K ohm and also drops to no ohms when touch probes. tried old 9v battery which comes in at around 8.2v. Led's glow both ways however the voltage I get is exactly half of the battery ? where did I go wrong. Many thanks Matt......just attached DC 5v from bench power supply and read 5v ?? tested battery and definately just above 8v...strange. Further to this it works fine and discharge various capacitors really well.
Matt Homer
2021-01-16 14:48:06 +0000 UTChttps://youtu.be/fYfIMl8M76s
Steve Edwards
2020-09-02 19:10:15 +0000 UTCNIce! Built this with 2 x 100W resistors so they fit in a smaller box:
Steve Edwards
2020-09-02 19:10:12 +0000 UTCHi Paul, I was wondering what the insulation jacket is that you are using to cover the resistor lead wires? Also is there a standard diameter for most THT components?
David Armstrong
2020-05-28 14:55:42 +0000 UTCyes the smart one will be cool!
Robert Hollingsworth
2020-05-04 21:29:52 +0000 UTCYes to the smart version!
Sam
2020-04-04 18:33:43 +0000 UTCI for one would love to see the schematic modified with both of these additions! I would greatly appreciate it if you do!
Elisamuel Resto Donate
2020-03-20 02:45:13 +0000 UTCThanks! I just bread boarded a version of your circuit and got an education about LED's. Amazing little devices. I could comfortably monitor the discharge down to about 2.3VDC by just observing the LED running at less than 1mA. The sky blue High Bright's I've been saving are also beautiful. I bought these after a review you did on them some time ago.
82abn34
2020-02-12 10:04:47 +0000 UTCLove the extended idea. First thing I'm gonna build is this :)
Twobob
2020-02-08 01:13:34 +0000 UTCPaul, I just built this thing and it is amazing, as expected. A few things I thought of, you mentioned an active version, so here it goes: battery supplied analog feature with the following extra functions * constant current discharge, * analog selection of current based on measured di/dt, so increase current if measured RC is large, * default current is small, * active constant current using a HV FET
Stefan Lindberg
2019-12-01 13:54:07 +0000 UTCI am getting ready to build this and I have two questions. Does the aluminum plate need to be any specific thickness and do the resistors need heat compound between them and metal?
Rick kennard
2019-11-04 22:12:40 +0000 UTCHi Paul, after building your amazing super probe and leakage tester I now found the time to build this device. All your devices are incredible useful tools. Thank you.
Jürgen Driessen
2019-10-31 13:00:06 +0000 UTCI made a "deluxe" version, 10mm LEDs in nice panel holders with safety banana jacks, should keep myself from forgetting having the meter leads unhooked and accidentally shorting them :)
Sebastian
2019-10-23 20:26:06 +0000 UTCI built this and I added a switch to short out 3 of the 4 1K shunt resistors. If I am working on <200V system I can leave the switch in the 1K position. I also added a LDR+Resistor voltage divider (opto isolator) plus a 9V battery and transistor. Now it beeps until the charge is gone so I can use it in daylight and don't have to take my eyes off the board I am working on (I also added an LED so I get a nice bright LED as well as the buzzer). The two 'hot side' LEDs are placed opposite the one LDR and I also added two extra externally visible LEDs so I can use it without the battery, if required.
Steve Simmonds
2019-10-18 18:53:50 +0000 UTCI vote YES for the high and low voltage version.
Ron Santos
2019-10-06 12:33:31 +0000 UTCThanks for sharing this design Mr. Carlson. It's sure better than probing around with a screw driver and making a mess.
John Gilliland
2019-09-20 16:27:49 +0000 UTCWhat is the correct way to use this? Some people clip one lead to ground\chassis - others go directly across each cap. Consider four 100V rated caps in series with 300V across all four caps. Now if you use one probe on GND and then discharge the 'hot' end of this capacitor chain, will this cause damage? Alternatively, if you short across the 'hottest' capacitor at the end of the chain, that cap will now have 225V but no LED will be lit - if you now discharge the next cap, it will leave the top cap at 225V, etc. etc.. So 'how should we safely discharge caps if we don't know how they are wired'? Is it important to beware of series 'chained' HV caps and how do we safely discharge such a circuit?
Steve Simmonds
2019-09-12 10:29:35 +0000 UTCPaul, you come up with some of the most astoundingly wonderful designs! Designs that are SO very useful and helpful to anyone working in electronics!!! I have a suggestion for your upgrade, the "intelligent" one. Instead of having leads come out for connection to a DMM, since you are only measuring voltage, incorporate a built in voltmeter with LCD or LED type display and only have the leads to the capacitor come out of the box.
Wayne Thompson
2019-09-06 07:36:32 +0000 UTCThat insulated wire appears to be high-temp fiberglass.
Frank B.
2019-08-18 15:47:09 +0000 UTCWhat are you using to insulate the wires? Some sort of nylon wire loom? I am trying to source an equivalent so any details would be appreciated.
Brett Becker
2019-06-12 06:35:25 +0000 UTCI would be interested in the intelligent capacitor discharge circuit.
John Jones
2019-05-31 20:45:55 +0000 UTCYou're welcome!
Mr Carlson's Lab
2019-05-24 22:49:07 +0000 UTCA very big thank you Mr. Carlson. I just finished your capacitor dicharge divice. My very first electronic project. Thank you for all the hard work and sharing your knowledge with us.
M Rautenbach
2019-05-24 21:06:10 +0000 UTCMr Carlson, you said in the video that you were going to show us your brand of super glue, but you didn't! :-P
Bruce Dow
2019-05-18 18:04:26 +0000 UTCMicrowave oven capacitors can have a charge as high as 2,800 V so the answer is no, because that would exceed the 1,000 V rating of the probe leads.
Bruce Dow
2019-05-18 18:02:25 +0000 UTCThanks again, Paul! I just received the components for my CDD in the mail today. I just need to get to the hardware store to find some aluminum or copper for my heatsink, and some nylon hardware.
Robert Calk Jr.
2019-04-06 04:33:47 +0000 UTCHi Paul would it be possible to get the PC Board lay out in the for of Dip Trace system (.dip)
Paul Pain
2019-03-23 19:34:57 +0000 UTCHi Paul. Thank you so much for sharing with us your vast knowledge and experience. I have already learned tons from you. I am building this neat device right now. Instead of buying the project box and drilling the holes in it, I 3D printed one to Hammond's specifications but with the stand-offs already built in, some labels and graphics on the top, ventilation slots in the bottom and on the sides and lipped (collared) smooth holes for the leads to eliminate grommets. I am going to use 10mm red LEDs with 5600mcd brightness. I hope they will be big and bright enough to see any residual voltage. I will post some photos when I finish. Question: you mentioned some extremely good industrial Super Glue you use. Any chance to share the details? The standard Super Glue I am able to source here in semi-rural Australia is "good for everything" (read "nothing"). Thank you again for your indescribable help!
Jaroslaw Janiszewski
2019-03-22 02:57:57 +0000 UTCOnly one path, one circuit. Two separate circuits introduce redundancy (extra safety.) Your circuit will work just fine, but if one 68K resistor fails, you have no indication in either direction.
Mr Carlson's Lab
2019-03-17 03:09:13 +0000 UTCWouldn't this be a simpler and equivalent circuit: <img src="https://alo.fi/MrCarlson-Patreon-only/Capacitor-discharge-001.png"><a href="https://alo.fi/MrCarlson-Patreon-only/Capacitor-discharge-001.png" rel="nofollow noopener" target="_blank">https://alo.fi/MrCarlson-Patreon-only/Capacitor-discharge-001.png</a> ?
Antti Louko
2019-03-16 17:06:27 +0000 UTCYou're welcome Brian!
Mr Carlson's Lab
2019-03-08 09:58:25 +0000 UTCNeed to build this project. Thanks Paul.
Brian Dresser
2019-03-07 16:23:59 +0000 UTCcould you move the interior forward a bit and mount a small meter in the top face?
Lewis E Brockman
2019-03-05 15:28:08 +0000 UTCHi George. The more diodes you add, the quicker the LED extinguishes before the capacitor discharges, (each diodes forward is about .6 Volts.) With a bridge rectifier, you add two diodes in each direction. Two LED's also give you a separate reverse test if you don't trust the opposite reading.
Mr Carlson's Lab
2019-02-18 20:44:27 +0000 UTCWhy dont you put full wave rectifier parallel to the led and throw out the other led? (only one led will be more estetical and professional looking)
Georgi Kolev
2019-02-18 20:16:05 +0000 UTCHi Paul - is it possible to use this discharger to discharge a microwave capasitor, or is it too high voltage in those caps?
Asle Runar Borgersen
2019-02-12 21:57:47 +0000 UTCOK, I think I've located the test leads you used in your project. Are they from Banggood? "PT1003 1000V 20A Banana Universal Multimeter Test Probe Leads Cable" $2.96 + shipping
Dave Bacon
2019-02-08 22:48:50 +0000 UTCPaul, do you have any suggestions on where to purchase the 1000V, 20 Amp rated probes/test leads. Amazon has a few cheap selections (around $8 US) but I'm not sure I would trust those. I like Probemaster test leads, but the cost is a bit out of reach. (And I'd hate to cut them up) Thank you. -Dave
Dave Bacon
2019-02-08 22:13:38 +0000 UTCHi Ronald. The component count is so low, I didn't include a list. Between the video and schematic, all the information needed is supplied.
Mr Carlson's Lab
2019-02-08 08:10:17 +0000 UTCHi Paul.I think you once had a parts list for the capacitor drain,and i can't find it.Ronnie.kn4u@comcast.net.
Ronald May
2019-02-07 21:27:46 +0000 UTCHi Paul. Thanks for what you do I would really like to see the smart version.
Mike Katchur
2019-02-05 02:25:30 +0000 UTCI would love to see you goin' on by extend the functionality. Thank you very much for your work!!!
Ronald B.
2018-12-20 16:31:33 +0000 UTCYou're very welcome Jonathan!
Mr Carlson's Lab
2018-12-13 09:13:08 +0000 UTCHi Paul. Thank you for sharing your time and talent on Patreon. The capacitor discharge device was my first project. It passed all the tests, and I'm looking forward making my first PCB for the SIFT project.
Jonathan P. Oehler
2018-12-12 22:20:57 +0000 UTCHi Paul. Thanks for this project, just finished mine in abt. 2.5hrs. Now I can safely start with the signature tracer project, my old Heathkit is already waiting to get modified (and discharged ;)
Thomas Frank
2018-12-12 20:30:29 +0000 UTCHi Paul, you used som kind of heat / isolation hoses for the 68k resistor etc. What is the exact name for it? I can't find anything here in Germany. I gues because of using the wrong name of it...
Ronald B.
2018-12-12 19:50:30 +0000 UTCThanks Paul. Great project. Is it possible to provide a closer look at the LED wiring to termination points within the assembly please. It gets a little busy within this area so a little more detail would be greatly appreciated. Thank you.
Sebastian Zammit
2018-12-02 03:45:55 +0000 UTCHi Dave. Sure its possible to share here. When you are done, post a link in the community section. If you post off this site, make sure no schematics or drawings from my design are included, as this circuit is part of this course and is to remain on Patreon. Other than that, feel free to post your enclosure.
Mr Carlson's Lab
2018-11-24 16:21:42 +0000 UTCI've also designed a laser cut press fit enclosure for this project. Once I build mine and finalize it, I'll share the AI template for those who'd like to go that route. Is it possible to share here, or should I just post a github link to files? Thanks!
David Cool
2018-11-24 14:54:29 +0000 UTCI really need to build a lower voltage capacitor discharger, I know this hasn't been designed or integrated into this build yet. In the meantime, I am looking at this design: <a href="https://www.instructables.com/id/Safe-Capacitor-Discharge-Tool/" rel="nofollow noopener" target="_blank">https://www.instructables.com/id/Safe-Capacitor-Discharge-Tool/</a> Any comment on this or ways to make better before I build one? Thanks!
David Cool
2018-11-24 14:46:50 +0000 UTCThis has not been designed yet. It's on the list though.
Mr Carlson's Lab
2018-11-19 17:16:44 +0000 UTCYou mentioned a box that would smart switch between low and high voltage capacitors, I'd love to see this circuit designed. I know this was designed for high voltage capacitors, that said would this not work with low voltage capacitors? Thanks!
David Cool
2018-11-18 22:41:04 +0000 UTCAny scrap piece of aluminum will be fine. Just make sure it has some thickness to it. I used the lid from another Hammond project box. Somewhat like pot metal.
Mr Carlson's Lab
2018-10-22 02:03:31 +0000 UTCPaul, Thanks for this video. I'm in the process of getting the pieces to build this, but I'm at a loss to find the Aluminum plate you use to mount everything on. Could you give me some ideas of where to find one? Thanks, J.B.
James B. Taylor
2018-10-21 16:36:46 +0000 UTCPaul,
James B. Taylor
2018-10-21 16:33:45 +0000 UTCA low discharge incorporated into the unit would be awesome
William Barrett
2018-10-19 04:55:12 +0000 UTCHi Paul, I’ve just ordered a bunch of parts to make this. I am struggling finding 1N5339B here in the UK, they’re out of stock from my usual suppliers (RS and Mouser) would a 1N5339BG part suffice? Also, I’d love to see us all build the low voltage discharge section into this. It would be a great All-In-One discharge device that would be a great tool! I have changed the project box also, think mini analogue scope type of deal with carry handle/foot.
Mick Curry
2018-10-18 21:10:50 +0000 UTCAnother suggestion for cases for isolated devices are the ones that have mounting threads for a baseplate. RND even makes some that have metal M-threads that are just so convenient. Also, they sometimes ship the right screws with the box so you just have to punch some holes into that aluminium bassplate and you're golden.
Philipp Hematty
2018-10-06 23:09:34 +0000 UTCA smart discharger would be great!
C.T.
2018-10-04 17:51:27 +0000 UTCYep, would definitely like to see how you design this using jellybean logic to automatically select the right capacitors. Will there be any relays involved? Analog? SSRs or is it SCR?
Kendall Austin
2018-09-03 09:39:13 +0000 UTCHi Paul, Yes the intelligent discharge unit is an interesting idea made with off the self parts. I hope more people are interested in seeing that disign.
William Miklavic
2018-08-18 20:18:46 +0000 UTCActually, go with 5 Watts
Mr Carlson's Lab
2018-07-19 20:00:47 +0000 UTCHi Paul. I am having big problems sourcing the diodes for this. I can get 1.5W or 3W but 2W in through hole are very hard to get hold of. Will the 3W be OK???
Ian Cooper
2018-07-19 19:48:41 +0000 UTCCool device. I discharge capacitors with a device like this: |--X-----X--| |--X-----X--| X are light bulbs rated at 230V/200W. However, your device is much cooler than mine is and it definitely takes less space. Heck, my device doesn't even look like a device. Lol
Kevin Van Hout
2018-07-07 15:31:51 +0000 UTCThanks Roy!
Mr Carlson's Lab
2018-07-03 03:38:12 +0000 UTCAll I can say is brilliant idea! I love to see the latest version. Thank sir Paul for sharing this neat design.
Escabusa Roy
2018-07-01 13:09:01 +0000 UTCCan’t wait for a intelligent model !!! Thank you for such useful device !
Vince
2018-06-27 18:25:12 +0000 UTCHi George. Your construction can vary in many ways. It's difficult to say either way without seeing your device. I can tell you, the resistors will get hot in some applications, is your epoxy going to transfer heat? Will your epoxy hold under hot conditions? The board you are planning to use is called perf board, or experimenters board. Are the holes spaced far enough to stop "arc or flash over?" There are many things to think about if you are planning to modify the existing design. Modification is not suggested.
Mr Carlson's Lab
2018-06-10 14:55:16 +0000 UTCI've decided to build the simpler, 2, LED version but the build technique is maybe a bit unusual. I plan to epoxy the 4, 50W resistors, to one side of my board and wire wrap the other components to the other side. Rather than use a PCB I am going to use a 2 3/4 x 3 1/2 pre drilled Proto board ? The board has copper around the holes so that they can be soldered and I don't know what it is called. What say you, do you see any worries ?
George Noyb
2018-06-09 15:23:18 +0000 UTCThanks for your input Brian!
Mr Carlson's Lab
2018-06-09 13:27:53 +0000 UTCTesting the DD before boxing it up, works quite nicely! The only thing I'm thinking after doing some live tests is that an acoustic signal might be much more helpful than LED's, much like beep on multimeters. When discharging a bunch of caps elbow deep in equipment it's much safer to be looking where your hands are instead of away at the LED's and risk brushing up against another 'live' cap while rubbernecking.. Maybe a sound that goes from a high frequency (HV) down to low as voltage drops and then cuts off or even does a double beep like 'OK' when a safe level is reached.
Brian Crow
2018-06-09 01:25:16 +0000 UTCThanks for your input Phil!
Mr Carlson's Lab
2018-06-02 09:46:06 +0000 UTC+1 ... I'd like to see that smart version as well!
Phil McMillan
2018-06-02 08:42:25 +0000 UTCReally like how you build devices skookum. The KISS method is in play but I am changing it to Keep It Simple and Strong.
Donald (Don) Stewart
2018-05-27 20:11:00 +0000 UTCHey Mr C, why did you do this to calculate the power ? you could've juste used P=RI^2 could you not?
Tom DOMENGE
2018-04-26 10:26:41 +0000 UTCI did find these on eBay which look promising - <a href="https://goo.gl/whC63C" rel="nofollow noopener" target="_blank">https://goo.gl/whC63C</a>
Derek Cooper
2018-04-16 16:54:05 +0000 UTCHi Paul - great Patreon. Thanks for doing this. Question - in place of the probes (which are pricey), could we build some using brass like the ones xraytonyb built? <a href="https://www.youtube.com/watch?v=aVZe6J__ggQ" rel="nofollow noopener" target="_blank">https://www.youtube.com/watch?v=aVZe6J__ggQ</a>
Derek Cooper
2018-04-16 16:38:51 +0000 UTCHi Bob, check your PM's
Mr Carlson's Lab
2018-04-12 11:25:37 +0000 UTCPaul, Can you give a hint as to what part number(s) you ordered for the 1000V, 20A probes? I keep finding fake 20A probes. Thanks, Bob
Bob Vines
2018-04-11 21:44:57 +0000 UTCPaul,
Bob Vines
2018-04-11 21:41:38 +0000 UTCSince this is recommended for 600v or less, is it a linear progression to make one suitable for 3KV? that is replace the main 1K's with 4K resistors, (and increase the LED protection accordingly). I am starting to work with linear amplifiers and the HV supplies are in the 3KV range, so to service them (power disconnected of course!) I'd need to discharge the filters and the tubes. Thoughts? (fully understanding this is "at my own risk" google sends me in many different directions and some of them don't look safe)
Dave Bradshaw
2018-04-02 20:04:05 +0000 UTCLOL, a bit late yes, but as you say, "better late than never." Good job by the way, that's pretty close to my original.
Mr Carlson's Lab
2018-03-27 07:32:39 +0000 UTCHey guys! Finally I've managed to draw the schematic..) Better late than never, right? xD <a href="https://app.box.com/s/hzfz2ln3xompt0050mq6gkjwmal81h8o" rel="nofollow noopener" target="_blank">https://app.box.com/s/hzfz2ln3xompt0050mq6gkjwmal81h8o</a> Now I can enjoy Paul's video and see the original diagram! Thank you! Regards, Phil
Phil
2018-03-27 05:56:34 +0000 UTCI guess that in this case the LED brightness would vary a lot more since there is no zener clamping the voltage across it. To preserve this feature you could put two zeners in series facing in opposite directions (so they would clamp the voltage to zener voltage + 0.5V), and in parallel to them - two LEDs in reverse parallel arrangement and a 300 Ohm resistor. Plus the two 68K resistors. This would act pretty much the same as your circuit but would save 2x 68K and 1x 300 Ohm resistors.
Glebs
2018-03-26 03:10:39 +0000 UTCI know I am kinda late to the party but wouldn't it make sense to wire the LEDs in inverse parallel configuration? This way you can get rid of two 68K resistors, two 300 Ohm resistors and the zeners. LEDs would limit the reverse voltage for each other to their forward voltage, and the two 68K resistors in series would be enough to limit the LED current.
Glebs
2018-03-26 01:16:28 +0000 UTCLePage Super Glue Liquid Pro
Kasey
2018-03-20 02:06:51 +0000 UTCAt 14:45 or so, you indicate that you'll reveal your super super glue, and unless I was asleep at some point, you may not have. :o) Also, is the wiring you used to assemble the big resistor pack teflon insulated to help it manage the heat?
Merritt Derr
2018-03-19 11:24:36 +0000 UTCHi Greg, After the cap has been discharged, using a jumper clip and shorting the capacitor terminals is fine.... just don't forget to remove the clips before applying power again. Many new caps come in boxes with foil pressed on the contacts to prevent charging while not in use.
Mr Carlson's Lab
2018-03-18 07:49:15 +0000 UTCPaul, wonderfully simple circuit but very effective. A question if I may. I've seen some capacitors after I discharge them (normally with a 10W resistor) actually start re-charging ; i believe its called dialectric absorption. is it worthwhile leaving this device attached for a period of time to ensure it stays discharged, and, if so, how long for?
Greg Winfield
2018-03-17 11:07:26 +0000 UTCHi Justin, simply shorting the CRT to the chassis should be sufficient. The CRT holds a charge with not enough current to hurt itself. Make sure you use the appropriate tools to do this discharge. There are some crazy high Voltages stored in CRT's. If you are unsure of what you are doing, DON'T go near the CRT.
Mr Carlson's Lab
2018-03-15 22:45:19 +0000 UTCWould this circuit be appropriate for discharging CRTs? While my main scope is a Rigol DS2202A I have a Tektronix 2246 that I use from time to time for sanity checks. I bought it on ebay about 2 years ago in pretty good condition and it worked fine until the last time I relocated my lab. Now I am not getting a trace. The digital readouts and cursors still work and the beam finder works but no signal. If I wiggle the trigger level around a bit it will flicker on and off and briefly show the signal. I am about to open it up and while I have no intention of working on the CRT (I suspect it will be a trivial mechanical issue with the trigger circuitry) I still would like to discharge the CRT properly. The service manual seems to suggest just directly shorting it to the chassis but I figure since I built this discharger it would be better to have a controlled discharge. I cant say I ever had to discharge or work on a CRT before though. Not sure if this is a bad assumption.
Justin
2018-03-15 07:02:58 +0000 UTCThat would be a great idea James!
Mr Carlson's Lab
2018-03-13 06:58:45 +0000 UTCHey Paul, have you thought of putting a tone on the discharge, with a piezo. When you start to discharge you get a high tone and then as it discharges the tone becomes deeper. I have use one like this on lower power circuits and it can really help when its difficult to see a meter.
james holman
2018-03-13 00:54:25 +0000 UTCWith four 1K Ohm resistors, the lowest resistance obtainable would be 250 Ohms. This would drain some of the larger low Voltage , high "uF" capacitors slowly.
Mr Carlson's Lab
2018-03-12 06:53:14 +0000 UTCreally what i meant was at the end of the video you described making this unit smart and that it would decide after placing the probes on the capacitor how it would drain the capacitor. Im not sure what the lowest value should be on the capacitor. I guess whatever would be most useful.
Jeff hill
2018-03-11 10:45:56 +0000 UTCThat looks nice Jeff. When you say low voltage, how low?
Mr Carlson's Lab
2018-03-11 08:53:28 +0000 UTCI am looking forward to learn how to modify this to low voltage capacitors. Thanks Mr Carlson thisthis<a href="https://www.dropbox.com/s/3p7yrxhr2etje4z/IMG_2110.jpg?dl=0" rel="nofollow noopener" target="_blank">https://www.dropbox.com/s/3p7yrxhr2etje4z/IMG_2110.jpg?dl=0</a><a href="https://www.dropbox.com/s/kdifnvcsh11i2hn/IMG_2108.jpg?dl=0" rel="nofollow noopener" target="_blank">https://www.dropbox.com/s/kdifnvcsh11i2hn/IMG_2108.jpg?dl=0</a>
Jeff hill
2018-03-11 02:48:29 +0000 UTCThanks for your input Charles.
Mr Carlson's Lab
2018-03-10 21:38:32 +0000 UTCLooks like a nice clean job Bill! The resistors look to be half Watt types. They may get hot with extended use.
Mr Carlson's Lab
2018-03-10 21:36:32 +0000 UTCHere's a photo of my build: <a href="https://www.dropbox.com/s/su94mbmgp43ms73/CapDischarge.png?dl=0" rel="nofollow noopener" target="_blank">https://www.dropbox.com/s/su94mbmgp43ms73/CapDischarge.png?dl=0</a> I see that some others have mounted the LEDs on the board. I like that idea. I think it's cleaner, but I had already drilled the holes. :)
Bill Strider
2018-03-10 19:07:22 +0000 UTCLast comment was just my second try at posting a comment. Helps to end in a <return> ;-) Thanks for the reply. Still wouldn't mind seeing you USE this "STICK", btw. </return>
Charles K White
2018-03-10 01:21:54 +0000 UTCPlease define, "trying again?" CRT's are usually discharged with a long shorting stick. No special device needed as the current capacity of the tube isn't enough to damage itself.
Mr Carlson's Lab
2018-03-07 18:24:52 +0000 UTCTrying again ... I would STILL like to see how you discharge the o-scopes ' CRT. A further project box, perhaps?
Charles K White
2018-03-07 18:00:58 +0000 UTCHi Andreas. I could write a book at this point. First, this device is designed to discharge capacitors "safely," so "gross misuse" when anything is released is to be expected. Expecting an LED to "hold down" 600V is not good practice for many reasons. If the junction fails and arcs inside, the head of the LED will pop off due to internal pressure (gas) build up. The Zener is "protection at all costs" to keep that LED safe, as this is an indicator of charge. The added current limit resistor in line with the LED is even more protection (see the theme here) This circuit has a ton of built in redundancy.
Mr Carlson's Lab
2018-02-26 01:42:08 +0000 UTCI started to build my own discharger and made some calculations and measurements and some questions came to my mind. What was your thought about using the Zener at 5,6V 5W? The maximum current through the 68K resistors would be about 4,4mA. That would produce a maximum voltage of (300 Ohms x4,4mA) + 1,8V = 3,12V over the Zener. That means the Zener never conducts in the reverse mode. It only functions as a diode with 0,7V drop in the forward mode. The Zener would start to conduct and restrict its voltage only if the capacitor had a charge of more than 1700V. As a conclusion, if I’m right, the Zener could be replaced by a simple diode (1N4007). A second point is the 300 Ohms resistor which also could be omitted as the current is already limited by the 68K resistors. This makes the use of the Zener even less useful because the LED itself restricts it voltage to under 2V. A last point is the power rating of the Zener (at 5W) seems overrated to me. If I assume there is no LED circuit but just the Zener with the 68K resistors, the current flow is about 4,4mA. As the rule is to use 1/10 of the maximum allowed current of the zener, the maximum current would be 44mA which results in a max power rating of 44mA x 5,6V = 0,246W. This is just for the calculation as I think the Zener is not necessary and a diode would be enough to protect the LED. Please let me know your opinion on my thoughts and if I missed something. The resulting circuit would be the following: <a href="https://drive.google.com/open?id=1EqcAwZMl5vxX1ejN5XwROKTqIOJP8vbU" rel="nofollow noopener" target="_blank">https://drive.google.com/open?id=1EqcAwZMl5vxX1ejN5XwROKTqIOJP8vbU</a>
Andreas Sidiropoulos
2018-02-25 22:00:45 +0000 UTCIf they are what they say they are, definitely yes. Those people have been emailing me non stop trying to send me free things to review. They seem very nice, but I don't want to advertise.
Mr Carlson's Lab
2018-02-25 16:35:11 +0000 UTCHi Paul. Would you trust these probes from Bangood? Cheap yes but... <a href="https://www.banggood.com/DANIU-1-Pair-1000V-20A-Banana-Universal-Multimeter-Test-Probe-Leads-Cable-p-91653.html?rmmds=cart_middle_products&cur_warehouse=CN" rel="nofollow noopener" target="_blank">https://www.banggood.com/DANIU-1-Pair-1000V-20A-Banana-Universal-Multimeter-Test-Probe-Leads-Cable-p-91653.html?rmmds=cart_middle_products&cur_warehouse=CN</a>
Bengt R Kiil
2018-02-25 15:13:55 +0000 UTCHi Tom! :^)
Mr Carlson's Lab
2018-02-25 06:45:16 +0000 UTCHey Tom, good to hear from you! Thanks for your input.
Mr Carlson's Lab
2018-02-25 06:12:19 +0000 UTCOOPs let's try that again! I hit "enter" by mistake. I personally would like to see the "smart capacitor discharger. As you know, like you, I work with both HV tube gear and LV semiconductor gear as well. Anyway, "Nice piece of kit!" I'm gonna look for parts this week. Tom
Tom M.
2018-02-25 00:02:12 +0000 UTCHi Paul:
Tom M.
2018-02-24 23:57:22 +0000 UTC1KV 20A leads are pretty common.
Mr Carlson's Lab
2018-02-24 04:14:27 +0000 UTCThanks Thomas!
Mr Carlson's Lab
2018-02-24 04:13:51 +0000 UTCThanks John!
Mr Carlson's Lab
2018-02-24 04:13:33 +0000 UTCAwesome video!
Thomas Mears
2018-02-23 12:22:35 +0000 UTCWonderful project, and quite useful too. I had no idea that LEDs require a zener diode for protection. I'll admit that threw me as far as creating a schematic goes. Keep up the good work, my friend.
John Inlow
2018-02-23 09:56:09 +0000 UTCAny suggestions where to find the test leads??,,,ebay?
Lee Stanford
2018-02-23 04:26:20 +0000 UTC...provided a switch which can handle the power can be obtained for a reasonable price!
Dennis
2018-02-23 00:36:38 +0000 UTCThanks for your input Matt!
Mr Carlson's Lab
2018-02-19 08:09:18 +0000 UTCWell done Mr. C. Your explanation was clear and I appreciated looking at the ideas of the other submissions. I over thought the redundancy a bit myself with the two sets of probes :) For future ideas I'm interested in getting a better understanding of mod / demodulation to transfer information using radio waves and a project taboot would be nice. Using your lessons for some homeschooling projects with the kids.
Matt Hogstrom
2018-02-19 03:34:59 +0000 UTCThanks for your input.
Mr Carlson's Lab
2018-02-19 00:02:48 +0000 UTCYou're very welcome Bruce!
Mr Carlson's Lab
2018-02-19 00:00:16 +0000 UTCThanks for your input James.
Mr Carlson's Lab
2018-02-18 23:59:48 +0000 UTCI would rather have built this project in a clear box. As I have built many test boxes I may not remember what the device is. With a clear box I can visually see the circuit and not question its application.
James Sit
2018-02-18 14:42:57 +0000 UTCI very much enjoy your complete explanation of the discharge box. I do like having an audible indicator so when discharging your eyes stay on the HV capacitor rather an indicator.
James Sit
2018-02-18 14:38:44 +0000 UTCVery cool project - I am absolutely going to build this. Clever to use the zeners to protect the LEDs from reverse bias - I didn't know about their intolerance for that. Once again, a great job Paul.
Bruce Davis
2018-02-18 04:56:24 +0000 UTCHi Dennis, it would... The only drawback to that is, you have to add the 2 extra diode's forward drop (in the bridge rectifier) into the equation. So the LED would stop glowing in the 3 to 4 Volt region, verses the LED glowing down into the 1-2 Volt region.
Mr Carlson's Lab
2018-02-18 02:05:01 +0000 UTCRather than the anti-parallel indicator circuit (Zener || R + Led) would a bridge rectifier with a single indicator circuit on the rectifier output work just as well?
Dennis
2018-02-18 01:48:40 +0000 UTCHi Jurgen, the glue is :"Lepage super glue liquid pro." It comes in a blue bottle, with a red and yellow label (white writing.)
Mr Carlson's Lab
2018-02-18 00:53:29 +0000 UTCA neat future project idea!
Mr Carlson's Lab
2018-02-18 00:43:25 +0000 UTCI can see it now: "Alexa, discharge C13 to a safe level and notify me when at 0 volt potential."
racerbob
2018-02-17 22:59:09 +0000 UTCYes, I second that.
Bill Strider
2018-02-17 19:44:40 +0000 UTCVery cool project, very cool ideas around here. Sure I am gonna build this. Since I am always careful with high voltages I concentrate visual on the probes during measurement. I was thinking about a piezo or something (like in DMMs). A short beep when the discharge process starts and a long one (or double or whatever) when the voltage is low enough to be on the safe side. Not instead of LED or DMM but additional. Btw. Paul, what was your superglue manufacturer you used to glue the leds?
Jürgen Driessen
2018-02-17 19:31:53 +0000 UTCCool!!let's build a stand along preamp that really works well for hf bands
Joseph Laney
2018-02-17 17:20:27 +0000 UTCcapacitor leakage tester project?
peter
2018-02-17 12:18:20 +0000 UTCCool device mr Carlson big thumbs up would be interesting to a smart cap discharge
Allan Mitchell
2018-02-17 09:52:42 +0000 UTCThat's a swanky circuit as a replacement for apprentices finding charged capacitors barehanded inside the laboratory's miscellaneous capacitor collection draw.
Frank
2018-02-17 04:32:21 +0000 UTCVery nice device Paul. Also, even though I never got close to working out the design from the parts list I thought it a very good way to make you think about how it might be done. I would also be very interested in a non-microcontroller method to do a smart discharge device.
RBE
2018-02-17 01:25:38 +0000 UTCThanks for your input Dave!
Mr Carlson's Lab
2018-02-16 23:26:29 +0000 UTCGood Idea, maybe something with a changing tone as it discharges.
Mr Carlson's Lab
2018-02-16 23:23:01 +0000 UTCYou're very welcome Ralf!
Mr Carlson's Lab
2018-02-16 23:22:07 +0000 UTCGreat, glad you enjoyed Philipp!
Mr Carlson's Lab
2018-02-16 23:21:41 +0000 UTC"What's so unpleasant about being drunk?" "Ask a glass of water." Ask a tree how it feels about getting hit by a relatively small bolt of lightning. Those pits in the metal degrade the current capacity and mechanical stability. Use the screwdriver technique to discharge a filter cap in a guitar amp too many times and the terminals will flex like they've been handled by Uri Gellar.
Peter Sage
2018-02-16 23:08:28 +0000 UTCI've never used vacuum tubes, so this sounds interesting. But also necessarily high voltage, which sounds discomforting :)
Rob Clark
2018-02-16 23:07:25 +0000 UTCWell done yannick... smart discharger? The kiss method with high voltage for me. How about valve project !?
peter
2018-02-16 22:45:06 +0000 UTCJust another thought. I still see the odd yoke scanned picture-tube in gear. Many situations the tube can end up with a massive charge on it because of the auga-dag coating and internal shadow mask... With the gear de-powered I used to discharge it with 2 screwdrivers one opening the EHT connection and touching the terminations and the other joining between it and the chassis... Not good .... A proper discharger would be great!
Pete Bronlund
2018-02-16 19:27:45 +0000 UTCCertainly like the idea of an 'intelligent' discharger. I hated it when fellow techs would discharge a big electrolytic by shorting it out with a screwdriver tip. It often made a sound like someone fired off a .22 round in the w/shop.. Usually the screwdriver wasn't theirs either but the one they just asked for loan from out my personal toolbox! Apart from burning the end of it and melting some the tag on the cap, it MUST do nasty things to the component's insides dumping all that energy so fast...
Pete Bronlund
2018-02-16 19:13:43 +0000 UTCSince you don't need a lot of wire between the discharge unit and the DMM, why not make your cut a foot (or more) from the probes? That gives you two usable probes that could be incorporated into a compact, low-voltage device, as Michal Nowicki suggested two posts up.
Bill Strider
2018-02-16 16:56:21 +0000 UTCWhat about adding an audible indicator so you don't have to look at anything but the cap you are discharging?
Michael Benoit
2018-02-16 15:29:50 +0000 UTCWhat do you guys think about a compact version - two alligator probes, some wire and miniaturized circuit attached to one of them? It would heat faster, but should be ok for small caps.
Michał Nowicki
2018-02-16 11:35:35 +0000 UTCCool Lesson Paul! & Congrats to the Winners! I've never thought about using the 4 mm shielded plugs hanging at the other end of the extra leads, Damn :D I like the idea of designing a smarter version and if possible in the same fashion like this project. Can't hardly wait to read your new parts list :) Great Teaching Style, thank you Paul!
Reb Elba
2018-02-16 10:28:55 +0000 UTCThis is so cool. Just yesterday I wanted to look up a device similar to this. Mr Carlson, my saviour! :)
Philipp Hematty
2018-02-16 09:41:29 +0000 UTCThat may be true but the average guitar amp may have this happen 3-4 times in 30 years of service. I have never seen burned cap terminals in some 45 years of doing this service. Just sayin' . Not trying to start an argument here.
Radio Amp Doctors
2018-02-16 09:19:07 +0000 UTCPaul covered this in the previous video. Instantaneous discharge with a clip lead or screwdriver produces a much larger static discharge, and the resulting plasma vaporizes chunks of the capacitor leads or terminals.
Peter Sage
2018-02-16 09:07:39 +0000 UTCThat's a lot of heat dissipated by those wee 2W resistors! What about putting each indicator across one of the 50W resistors so they only see 1/4 the voltage?
Peter Sage
2018-02-16 09:02:28 +0000 UTCNot to belittle this circuit or certainly not you Paul, why not use a clip lead or screw driver to discharge the caps? This method has always kept me from getting zapped.
Radio Amp Doctors
2018-02-16 08:35:34 +0000 UTCHi Bill, the wire is solid #18 in a piece of lead dress.
Mr Carlson's Lab
2018-02-16 06:40:20 +0000 UTCGreat to read Smitty!
Mr Carlson's Lab
2018-02-16 06:38:01 +0000 UTCThanks Robert! That cam produces lots of Nox.
Mr Carlson's Lab
2018-02-16 06:37:11 +0000 UTCGood on ya, Yannick & John! Hah, this month I was busy as hell with my every day job and, surely, I'm late with the design) As a matter of education, I won't watch the vijeo and check out other members' schematics till I draw it myself and publish my diagram here) Thank you Paul! Anyway, I liked your video up front, cause I know it's right stuff :) Cheers! PS. I like the idea of designing devices together, it's very inspiring! IMHO
Phil
2018-02-16 05:35:20 +0000 UTCGreat content. Parts just arrived today, so your timing was great also. As a retired automotive tech, I am looking forward to modifying the device by adding some "intelligence". Keep up the great instruction. I was impressed by your EGR controller for the FireChicken also. Nice solution to a fat camshaft swap.
racerbob
2018-02-16 05:10:29 +0000 UTCThanks for sharing this great video. I was thinking to use a analogic voltmeter in the box (no power supply required). And yes for the intelligent version. Always interesting to deal with high voltage.
Axel
2018-02-16 03:04:05 +0000 UTCGreat video. I would really like to learn how to make it smart without a MCU. I think somehow with zeners . Just guessing on how to make it smart.
Cleveland Prescott
2018-02-16 02:55:09 +0000 UTCGreat video of a useful implement. I must build this - it would safer and more informative than my current crude method! Thanks as always...
Jim Gardner
2018-02-16 02:19:27 +0000 UTCKudos, John and Yannick! Great project, Mr. C! I am always impressed by your thoroughness and insistence on safety. I, too, would like to see the intelligent version, and I wondered if the need for a DMM could be eliminated altogether with the use of a series of LEDs that would extinguish one by one as the voltage dropped? A bar-graph, of sorts? Thank you for walking us through these projects and procedures!!
Jennifer LaChance
2018-02-16 02:16:02 +0000 UTCGreat job, Yannick and John! Also, a shout out to Neonuros, who figured out that the second set of probes should go to a meter. Paul, I'm definitely interested in your intelligent version. Also, one question. The white hookup wire connecting the big resistors -- is that 14 gauge? And above all, thanks for the clear and instructive video.
Bill Strider
2018-02-16 01:44:22 +0000 UTCVery nice and I would like to see it turned into a smart checker! I've just been using a simple probe with a clip on one end and resister in the middle. I like your a lot more and will have to give it a go on building one.
Steven Brauch
2018-02-16 01:37:03 +0000 UTCPaul, I agree with Dave and Andre about adding a cheap DMM into the discharge box itself (I hadn't noticed the link to add in more comments -- there are 11 now). I like the idea of not having to add the DMM (for safety) by having one built in to the box. I'd also like to see the Smart Version too!
Bob Vines
2018-02-16 01:33:15 +0000 UTCWay to go Yannick and John, Of course now I am bummed out, I was sure I had it figured, just goes to show you what tunnel vision will do. Looks like nobody had the other leads figured as a quick connect to the volt meter. Very neat feature, nothing worse than trying to hold a bunch of connections at the same time, especially with the voltage we are talking here. Paul, I know you are chasing out the cobwebs from this rusty mind. First time I woke up with a vision of how to do something in years. All sorts of projects are coming back to life around here. Thanks. Would be interesting to see the trick automatic version and how that is done. Steve
Steve Crisp
2018-02-16 01:02:34 +0000 UTCGreat work Paul! I will look at future projects a little differently now because your explanations help so much. Thank you!
Smitty Nash
2018-02-16 01:02:32 +0000 UTCI was thinking the same thing as Dave about putting a Cheap DMM in the box itself. I would love to see the Smart Version. Thanks Paul.
Andre Gopee
2018-02-16 00:34:09 +0000 UTCNice circuit design Paul.. I learned more about diodes... It would be nice to incorporate one of those cheap DMM LED panels right into the box, so you don't need an external DMM and can sit it on a shelf and see the discharge voltage without having to drag it out every time you need to discharge something... More like a "bench" device. I was rather surprised by the slow discharge rate, considering that other videos I've see will use a 500ohm-1000ohm resistor only for discharging... Even though it might heat up more,it would discharge the cap faster..
Dave Leger
2018-02-16 00:29:03 +0000 UTCGood to know, thanks Yannick.
Mr Carlson's Lab
2018-02-16 00:14:07 +0000 UTCWheres that sense of adventure Bob? :^)
Mr Carlson's Lab
2018-02-16 00:13:23 +0000 UTCNice. Instead of making it "smart", I was actually thinking if making it more simple by removing the LED circuitry all together. The DMM seems to do a nicer job of letting you know when they are completely discharged.
Bob Snyder
2018-02-16 00:10:41 +0000 UTCThank you Kasey. And Paul, it's not easy for an English person to pronounce my name i know, specifically Turcotte but you did it correctly :) I enjoyed the video thank you! :)
Yannick Turcotte
2018-02-16 00:00:46 +0000 UTCNice job Yannick and John!
Kasey
2018-02-15 23:27:14 +0000 UTC
