Re: SCR's

To: tesla-at-poodle.pupman-dot-com
Subject: Re: SCR's
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 18 Mar 1997 23:24:42 -0600
Approved: tesla-at-stic-dot-net

Subject: 
        Re: SCR's
  Date: 
        Mon, 17 Mar 1997 19:56:20 -0800 (PST)
  From: 
        "Edward V. Phillips" <ed-at-alumni.caltech.edu>
    To: 
        tesla-at-pupman-dot-com

I am using a QUADRAC right now to discharge a 3 ufd capacitor 
charged to 600 volts through a GM "high-energy" spark coil
obtained from auto junk yard for $5.00 each.  Can easily 
break down the coil externally (without damage).  Two coils
connected "back-to-back" and operated in oil (plastic refrigerator
container filled with mineral oil from Savon) easily give a
5" spark between sharp points when run with the same driver.
The QUADRAC is a TECOR Q6015LT, rated at 600 volts and 15 amps.
The capacitor is charged through a 6 henry 100 ohm choke from
300 volts DC (voltage doubler from 60 cycle line) and the
QUADRAC is operated in a self-triggering mode.  Should have
said the capacitor is charged through an inductor with series
diode (two 1N4007's in series), so that it peak charges to
twice the supply voltage and awaits the next self-trigger of
the QUADRAC.  Very simple circuit and the only time I have blown
the QUADRAC was when I accidently used too large a gate capacitance.

I found that the "hot" spark coils from the hot rod shop didn't
work as well as one of the GM coils, and were in the $30+ range.
The GM coils can be found in the distributor caps of Cadillacs,
Buicks, and Oldsmobiles of about 1990 vintage, and local junk
yard has a large quantity available for the price mentioned.

For what it's worth,
Ed Phillips