Use for crazy high value cap - Page 1
Forum section: electronics / general

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 10, 2014, 10:04:55 pm
content: I have access to a couple of 400V, 22,000uF capacitors. They're like 3-4 inches tall. Is there any practical homebrew application these could be used for aside from setting things on fire?

author: houdini
author_rank: Regular Contributor
timestamp: January 10, 2014, 10:28:24 pm
content: yes there are lots they could be used for a coil gun or as buss capacitors for some high power stuff. Look at 4hv.org there are lots of things that use such caps.

author: M. András
author_rank: Super Contributor
timestamp: January 10, 2014, 10:36:03 pm
content: spot welding?

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 10, 2014, 10:56:11 pm
content: Quote from: houdini on January 10, 2014, 10:28:24 pmHmmmm. I also have a bunch of 400-450V 480-540uF caps... You can build a heluva coil gun with those.

author: poorchava
author_rank: Super Contributor
timestamp: January 10, 2014, 11:04:02 pm
content: Medium power etg cannon.

author: AG6QR
author_rank: Frequent Contributor
timestamp: January 10, 2014, 11:14:28 pm
content: Photographic flash units with xenon strobe tubes can operate somewhere in that order of magnitude. 60 Joules or so is common for the battery operated flash units that attach to the top of a news photographer's camera. The flash units that are used in a professional portrait studio might be 500 to 2000 Joules, sometimes more. If you charge that capacitor all the way up to its 400V rating, you should get something like 1760 Joules. It'll make a bright light for a brief time.Whatever you do, that's a potentially lethal amount of energy, so treat it with the respect it deserves. Once I was bitten by a 60J flash unit that was "discharged" but still had a bit of residual charge remaining. Never again.

author: rexxar
author_rank: Frequent Contributor
timestamp: January 10, 2014, 11:33:21 pm
content: Quote from: M. András on January 10, 2014, 10:36:03 pmThat was my first thought as well, but I'm pretty sure you need a whole lot more energy to do that.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 10, 2014, 11:36:35 pm
content: Quote from: AG6QR on January 10, 2014, 11:14:28 pmBelieve me, I know. I used to be cavalier about big caps. Then I got shocked by 480uF @~200V. I felt my heart stop, then start again. Also accidentally shorted a 560uF that was around 380V with a screwdriver: it sounded like a .22 gunshot, and I had a purple circle in the middle of my vision for half an hour. Now I don't fuck around with big caps without triple checking that they are discharged completely (DMM reads <0.1V).

author: GreyWoolfe
author_rank: Unknown
timestamp: January 10, 2014, 11:56:25 pm
content: +1 for the coil gun!!

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 11, 2014, 01:05:38 am
content: If you're into DIY auto stuff, maybe make a "mild hybrid" system that uses those caps to start the engine?

author: G7PSK
author_rank: Super Contributor
timestamp: January 11, 2014, 10:38:32 am
content: Power factor correction on large motors or welding plant. You will be amazed at how bright a bulb is if you put the across the supply to one, the filament pops pretty quick as well.

author: han
author_rank: Frequent Contributor
timestamp: January 11, 2014, 10:53:10 am
content: 1. Make an Impulse current tester ...2. Test MCB circuit breaker3. resonance tester for coil..