I made the trigger wheel with nothing more than a compass, drill,
rat tail file and a pair of tin snips out of .032" thick Al. I drilled a
bunch of holes and filed out the connecting material. The same way
Charles Taylor made the Wright Brothers crankshaft :)

The hub I had lying around from an RX8 trigger wheel test.
That of course was made on a lathe. A DC motor spun the trigger
wheel. The up time on the scope is the dwell time. The plug
fires when the wave goes low.

This is a very simple and cheap ignition system as Chev V8
coils with built in FET switch can be had for $30 each. Four are
needed. Timing is fixed around 22 degrees BTDC.
Same as most AC engines.

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Here are some better pictures of the crude pick up I made.
The secret to how well these work is the glass lenses.
That is why I use these particular parts as the infrared
beams are very narrow. One can space them as much as one inch
apart and they will still work well.  A lot of the one piece
devices do not have these lens so the spacing is a lot more
critical and intolerant of run out in the trigger wheel.

The NTE equivalent of the IR diode is #3028 and the NTE
photo TX is #3037.

The bolts are 4-40 one inch long and the nylon spacer
.3 inches long. Parts you can get in any electronic supply
store. You don't need to order from Digi Key or Mouser.
My local Fry's had them. Maybe not Radio Shack.

If you have an engine almost running and want to test this system
let me know and I will loan a system to you for a week.
The spindle that bolts to the shaft and holds the trigger
wheel is being machined as we speak.

Paul Lamar