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Re: [TCML] triggered spark gaps

Pertronix makes a "points eliminator" type of electronic ignition conversion for older vehicles and equipment. It uses a Hall effect sensor and a magnet ring which fits over the distributor cam. They are pricy, and subject to RFI.

I would suggest using a GM HEI ignition module (NAPA PN TP45) to switch the coil. "B" terminal to +12V along with (+) coil terminal, "C" terminal to coil (-), heat sink to ground. You can put in any digital signal to the "G" terminal. The "W" terminal (variable dwell) can be connected to ground or to +12V depending on the input.

Had a 93 Ford Probe which I converted to external coil using signal from ECM computer to "G" and "W" grounded. On my 1951 Ford 8N tractor I use a 2n2222 transistor with a 4.7k resistor to invert signal from the points. Collector to "G", base to points and resistor, other end of resistor to +12, emitter to ground, and "W" is connected to +12.

On 2018-09-18 12:46, jimlux wrote:
I'm getting ready to start experimenting with triggered spark gaps for
a TC - all the timing benefits of a rotary gap, but without spinning
blades of death.

What I'd love to find, and I'm hoping the TCML hive-mind can help, is
an off the shelf "electronic ignition" module - not capacitive
discharge, but something that basically is the "points replacement"
that I can drive with an optical link (for HV isolation).

The idea is to use a 12V battery, an electronic ignition, and a
conventional ignition coil as a robust trigger pulse generator for the
spark gap.

Something fancy like the MSD, which generates multiple sparks, isn't
what I want.. I want just the one pulse into the coil.

Back in the day, there were "points replacement" modules - maybe
something I can order as part of a HEI?
(after all there's the famous GMHEICSLR contest, which used the *coil*
of a HEI as the basis for a tesla coil of sorts)

Cheap is good. The ignition coils are $12 - I'm not wild about
spending $100 on what is basically a HV transistor and some biasing
resistors and capacitors.

(No, I don't want to build one from scratch.. been there, done that)

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