Instructables

Switch/Relay Question?

I've been working alot with capacitors recently at a voltage of 330v or so. I've been using this cap bank to discharge into whatever I feel like. Wires (to watch them pop), cds (to "erase" them), etc. Anyway, one problem I've been having is the switches. I flip the switch, it discharges the capacitors and it should work fine. The only problem is the switches are only worth one shot. And I'm using the biggest I can find. (Rated for 15 Amps). I realize that the capacitors are discharging instantly, and the amperage is probably higher then what its rated for, but I expected to get more then one shot out of it. Any suggestions besides a bigger switch?

(I've considered using a series of relays for each capacitor, but that gets expensive.)

Thanks!

iceng2 years ago
The choice of discharge switch a Silicone Controlled Rectifier ( SCR )
and are available in sizes ranging from 240 amps to 600 amps, with a voltage rating of 1,600 volts. 
schematic3.gif
transistorguy (author)  iceng2 years ago
This might be exactly what I'm looking for. This looks very promising.
How do you have a rubber rectifier ?
I have a couple hokey puck scrs.
Fun thing about them they require a centered force of ten or more pounds anode to cathode to make contact to even test.
Actually, for a one off, an SCR can switch 1000 of amps.
Well, what is the voltage rating of the switch? And is that rating for DC? It might be self-explanatory.

Qa
transistorguy (author)  Quercus austrina2 years ago
I believe it is around 250 volts DC, but when I charge up the circuit I rarely exceed 300. I felt a 50 volt difference, if that, wouldn't be too much of a problem.
Vyger2 years ago
What you might need is an old fashioned knife switch. Just Google it and you will see thousands of pictures of them. The regular switches that you have been using are not built for the high current so the contacts either fuse of melt. A knife switch can handle large current flows.
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