Capacitor bank charger - Page 1
Forum section: electronics / projects

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 02, 2013, 02:32:33 am
content: I have 5 200VDC 2000uF capacitors and I have absolutely no idea how to charge them. Can someone tell me what components I need?

author: Harvs
author_rank: Super Contributor
timestamp: February 02, 2013, 02:48:29 am
content: They're capacitors, not batteries. Why do you want to charge them???

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 02, 2013, 03:09:01 am
content: I'm making a coilgun.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 02, 2013, 03:29:42 am
content: If your mains is 120V, connect the negative side to neutral, and the positive side to a diode (1N4007 works well) and a 40W or so incandescent bulb in series to the hot. Double check polarity before plugging it in and remember that a charged cap is just about as dangerous as the mains.

author: Harvs
author_rank: Super Contributor
timestamp: February 02, 2013, 03:51:10 am
content: Grab the charge circuit out of an old camera flash. They contain a small flyback circuit that charges up the storage cap to a couple of hundred volts. You may need to limit it, from memory they usually go above 200V.

author: Kevin.D
author_rank: Frequent Contributor
timestamp: February 02, 2013, 10:28:30 am
content: quote author=Harvs link=topic=13913.msg188171#msg188171 date=1359777070]Grab the charge circuit out of an old camera flash. They contain a small flyback circuit that charges up the storage cap to a couple of hundred volts. You may need to limit it, from memory they usually go above 200V.Shariar (signal path blog) has a very good video on using camera flash to charge capacitor ."Camera Flash and Nixie tutorial"http://thesignalpath.com/blogs/page/4/

author: PA0PBZ
author_rank: Super Contributor
timestamp: February 02, 2013, 05:28:11 pm
content: Am I the only one thinking that someone who has no idea how to charge a capacitor should not try to make a coilgun?

author: M. András
author_rank: Super Contributor
timestamp: February 02, 2013, 05:51:15 pm
content: let him play with it, worst case you will be invited to give him a darwin awardbtw i wonder how he will solve the timing of the coils when he has no idea how to charge the caps

author: mrflibble
author_rank: Super Contributor
timestamp: February 02, 2013, 05:53:59 pm
content: Quote from: PA0PBZ on February 02, 2013, 05:28:11 pmHeheh, I had pretty much the same thought. But what the hell, there are worse ways to learn things.

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 02, 2013, 07:56:20 pm
content: Exactly. This is pretty much a test run for me. I'm trying to get into high voltage electricity.

author: lewis
author_rank: Frequent Contributor
timestamp: February 02, 2013, 08:22:32 pm
content: Quote from: NiHaoMike on February 02, 2013, 03:29:42 amNOT a good idea to even think about entertaining the possibility of considering doing this if you need to know how to charge a capacitor.Transformer!

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 02, 2013, 09:41:31 pm
content: I DO have an old car ignition coil. It's output is about 10,000V. If I got enough capacitors to match the voltage, could I do it that way?

author: mrflibble
author_rank: Super Contributor
timestamp: February 02, 2013, 09:46:09 pm
content: Okay, slowly step away from the lethal voltage device and put it down.I'm all for messing with 120 or so volt, provided you use a TRANSFORMER. 10 kV might not be the best thing if you have to ask.

author: mrflibble
author_rank: Super Contributor
timestamp: February 02, 2013, 09:48:28 pm
content: Also, whatever happened to the concept of learning how to charge/discharge your caps on oh I don't know a non-lethal voltage? Then when you get the hang of it and looked into safety issues a bit more you ramp it up.

author: M. András
author_rank: Super Contributor
timestamp: February 02, 2013, 09:56:11 pm
content: Quote from: Jeffrey Eagan on February 02, 2013, 09:41:31 pmyou dont want to discharge a 10kv cap array if you use few hundred or thousand microfarad caps there will be a damn huge bang when the wires vaporize

author: TerraHertz
author_rank: Super Contributor
timestamp: February 04, 2013, 09:57:55 am
content: Quote from: Jeffrey Eagan on February 02, 2013, 09:41:31 pm[Oh dear God...]Um... when you say "have an old car ignition coil. It's output is about 10,000V" do you mean you have something to drive the low voltage side already, and that's the output voltage you get? Or do you just have an old ignition coil all by itself, and are quoting a figure you got somewhere?Also, the terms AC and DC - do you know what they mean? What are you planning to use between the ignition coil and the capacitors?QuoteBe careful, high voltage electricity wants to get into you too.I don't mean to sound discouraging, but I get the impression you don't know enough yet to be aware of the dangers. Perhaps you should try some safer learning experiences first?

author: poorchava
author_rank: Super Contributor
timestamp: February 04, 2013, 10:07:13 am
content: You need some form of current limiting. When capacitor is fully discharged it is virtually a short when you start to charge it. Accidental shorting a 2000 uF cap charged to 200V is quite likely to cause an explosion. If not of the capacitor then you may get hurt by flying molten metal (that's not a joke).Stuff like that needs a current limited, or current controlled charge ciurcuitry and bleed resistors.

author: Analogtech
author_rank: Contributor
timestamp: February 23, 2013, 06:10:35 pm
content: Since I'm building my 5th coilgun now I have some experience on this topic the best way for you to charge those capacitors would be to use a regulated boost converter nothing fancy just a 555 timer based PWM driving a MOSFET which turns an inductor on and off and charges the capacitors using the HV voltage spike from the inductor and a couple of opamps to reset the timer and to indicate when its charged also trigger the capacitors using a SCR and put some bleed resistors on the capacitors and flyback diodes on the inductor and coil.take all safety precautions those capacitors can kill you also do not mess around with the mains if you don't have any experience

author: potatogun96
author_rank: Contributor
timestamp: March 11, 2013, 04:07:44 am
content: I built a very simple charger for my 10,000uf 300V capacitor bank. I connected the 120VAC mains in series with a light socket, then to a bridge rectifier. I connect the output of the bridge to the capacitor bank. I can put any incandescent bulb in the socket for different charge rates, the higher the wattage, the faster the charge. I can charge my bank in about 10-20 seconds this way.

author: smashedProton
author_rank: Frequent Contributor
timestamp: March 11, 2013, 06:10:51 am
content: Charge pump! They are fun. All you need is an oscillator with square output and 70 ish percent duty vycle. Current amp it using a fet, then run it into an inductor. Use a diode to allow the reverse charge to flow into the cap. Make sure that you use a big inductor. You can get away with a small one by raising frequency

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 17, 2014, 08:11:22 am
content: Haha. Thanks for the help guys, but I've given up on the whole "HV hobbyist" idea, I've moved onto bigger and better things!

author: lewis
author_rank: Frequent Contributor
timestamp: February 17, 2014, 08:59:38 am
content: That's a GOOD THING.

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 17, 2014, 09:33:25 am
content: Indeed it is! I've dropped all of the caps (tried to charge, and wouldn't. They dried out! Bummer!) Now I've gotten into audio and CCFL's!

author: lewis
author_rank: Frequent Contributor
timestamp: February 17, 2014, 11:01:21 am
content: Get into microcontrollers too, they're awesome! And safe.Start here:http://www.gooligum.com.au/tutorials.html

author: fcb
author_rank: Super Contributor
timestamp: February 17, 2014, 11:07:49 am
content: I'd consider charging them with a LOPT (line output transformer) from an old colour TV (35KV!) - pretty cheap and easy to use (555 timer and a FET on the primary).

author: dannyf
author_rank: Super Contributor
timestamp: February 17, 2014, 11:52:10 am
content: QuoteGood for you.

author: Jeffrey Eagan
author_rank: Contributor
timestamp: February 17, 2014, 06:27:30 pm
content: Thanks, Lewis!

author: wemme
author_rank: Regular Contributor
timestamp: February 17, 2014, 08:56:54 pm
content: Hello.When i built my coil gun i used a 400Vdc rail.My banks were charged from two isolated 240vac supplies one configured with a variac both were wired in series.I used a bridge rectifier and a 100W 240v light bulb as my charge circuit. when the light goes out your good to go.RegardsBart