> A friend has been given a bunch of 50,000uF 400V caps. They 
> apparently were ripple filters in some big-ass PSU. He wants 
> eventually to use them in a coilgun-type experiment. For his 
> own amusement I hasten to add (he has this thing about HV and 
> sparks !! ;)) and owns some Tesla equipment)
> 
> http://en.wikipedia.org/wiki/Coilgun
> 
> Any advice I/we can give him for a suitable and rugged trigger ?


You can get (not easily & not cheaply, ymmv) gas-filled reed switches,
relays and the like.  The gas stops arcing between the contacts.  Well, it's
supposed to.  Current might be a bit of bugger though...

Or like tasers work, with a spark gap.  Cap charges, arcs at the high volt
point, dumps the charge, rinse lather repeat.  Down side is you don't get
much of a say when it triggers.

By sheer coincidence, I encountered this:
<http://www.philpem.me.uk/elec/welder/> yesterday.  I thought the name
sounded familiar.  Phil reckons a 50RIA20 SCR would handle the current, he
doesn't mention the voltage as he's only using a few volts.  (I'm going to
parallel a couple of modified microwave transformers instead, 'cause I've
got them.)

Tony

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist