Originally Posted by ykobayashi

Unit


Board, basically two integrated circuits. One amplifies and possibly thresholds. The white plastic screw pot is probably an offset from what I can tell. Then the signal goes into the big chip which a microprocessor running at a few MHz. It is either sampled and processed digitally or just thresholded and converted to an output pulse to drive the light and the inductive pickup circuit.

Looks like the pickup circuit is pretty simple. I thought you needed high voltage like a spark plug line to trigger the clip on timing light but maybe just a little current will do. There is nothing remarkable here, just a switch as far as I can tell that turns the juice through the loop on and off. Funolas idea to use a bright LED as a strobe is good. No special circuitry there and you don't need an antique timing light. I literally had to go into my dad's garage and dig for our old Sears Craftsman Deluxe timing light. Useless today as modern gassers are coil over plug. I guess I can use it on my 65 F100 though.

All this is a guess of course because the designer used a 4 layer board and hides his tracing under top and bottom copper planes. I didn't feel energetic enough to dig further. He earned his money today as the system worked ok.


Sensor. Basically a few wafers of piezo ceramic material. Looks like Barium Titanate. Ground is on the injection tube and the other end connects to the screw. Voltage is across the screw and the tube. Looks easy to damage if you tighten it too much. These crystals are very brittle.