Paul,

am I correct in remembering that your unit will fire once with a trigger from a Hall effect sensor and maybe an LM1815?

I would be interested in trying to replace one mag on my IO 360 and see how it works- I would have to place magnets and HE sensors on the flywheel to make it work for testing. If it works, then I would make a part that would bolt in the place of the existing mag.

Or, I could easily write a bit of code for one of my boards that will let it fire at the right time for multiple sparks. I would probably start with single spark and go from there. Nothing to be affected by the noise from the discharge.

My Wheeler # 2 is flying, the one with the IO 360 Lycoming in it. Could use 4, and make them individual for each plug, or waste spark and use 2. I can even replace 1, 2 or up to 4 plugs and see how it goes. I have a full engine monitoring system that monitors CHT and EGT for each cylinder, so I can compare which ever cylinder(s) with the CDI to the regular mags.


Kevin Alderman
A&P, GROL, ASEL
Comm/Inst

Excuse me while I think out loud.
My CD coil requires a 15 usec 12V pulse  to trigger no more no less.

At 3000 RPM it takes 20 msec to make one rev.
A 4 cycle piston engine fires every other rev so that is 40 msec
40 msec divided by 360 degrees is  100 usec per degree.
so every 5 degrees is 500 usec. No problem at all.
In fact you could fire it every 2 degrees or every 200 usec.

I use a computer but if you program your own computer you can do it.
The coils alone are $200 each so you will need 4. The coils have a 5 amp
fuse wired in series with the 12 volt supply. Not because they draw 5 amps.
They don't. They draw less than one amp on average. The 5 amp is to handle
surges.


That is one LI CD coil per plug of course.

If you designed and machined a distributor to replace the mag and used a
4 cylinder off the shelf distributor cap and rotor you could get way with only
one LI CD coil. But not  firing each plug every 2 degrees.
The system needs a 100 usec breathing room per spark.

I am now using an optical link from the computer to the coil so you need a driver from the computer
to the coil such as a $1 CD4050. I have tested this with three CD4050 CMOS push pull gates wired in parallel.

Each CD4050 has six gates. Each gate will put out 5 ma at 85 degrees C at 12V. So the total
for 3 is 15 ma. This activates an LED in the coil. I did it this why to make the trigger line to the coil
immune from RF interference and spike feed back to the computer.  AKA a current loop.
It worked so well it amazed me :) One could wire all six gates in parallel if one wished.
The LED current limiting resister is in the coil.

The CD4049 is an inverter version of the CD4050.

Paul Lamar

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