Triggered gap controller

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

To TSG experimenters,

I have developed a variable freq pulse generator and dual ignition coil
driver for an experimental SPDT TSG for my DC powered coil.  The two
ignition coils alternately fire.  Greg Hunter kindly posted the circuits on
his fine site.  If you are interested, go to http://hot-streamer-dot-com/greg
and click on "TSG Pulse Generator" and "TSG Driver Circuit".
 One could easily adapt the circuit to drive just one ignition coil.  One
good safety feature is that the coils are isolated from the 120 V AC power
lines.

Some notes about the circuits:   I haven't tried the circuit in a TSG yet,
but it works well "stand-alone".  The  two circuits need to be isolated from
each other (e.g. separate boxes).  I tried it all in one box, but the driver
circuit coupled pulses into the pulse generator and affected performance.

 The pulse driver has a switch for two ranges of output.  Mine is about 1 to
100 and 10 to 1000 BPS.  The x1000 output is to monitor frequency more
accurately than just monitoring an output.  Pot should be audio taper to
make the pot position to output freq more linear.  I used a dual 100K audio
taper pot from Radio Shack, and wired the two sections in series.

 Pulse width is fixed - I set it so the regular ignition coils just start
saturating.  I don't know what the pulse width should be for HEI coils -
haven't bought them yet.  You can substitute a dual pot for the fixed timing
resistors in the one-shots if  you want to experiment with variable pulse
width.

I also used this setup to drive a bunch of neon bulbs in series as a
make-shift strobe light to calibrate my RSG RPM vs input voltage.  Worked
fine.  Radio Shack has a strobe light (bare bulb) for about $3.50 which
should be much brighter when driven from an ignition coil - I haven't tried
it yet.

If any of you use these circuits with a TSG, or make improvements to the
circuits, please let me know about it.