Kevin, your experiments with the 2nd gen igniter gave me another idea to try
for a cheap CD system. The 2nd gen lower mag sensor puts out 12 trigger pulse per rev.
Feed that to a FET that turns on and off the primary of a pulse transformer.
At 400 RPM that is 80 PPS. A simple circuit can double that to 160 PPS.
at 8000 RPM it is 266 PPS.
A common low cost ($30) 220 V 60 cycle control transformer is CT 24 volt to 220
volt. Use the 12V half to jack the voltage from 12 Volt square wave to 220 volts AC.
With a full bridge rectifier or voltage doubler circuit you might get near 400 volts
DC. Use that to charge the CD capacitor.
The old Heath Kit CD ignition used a control transformer and a mechanical vibrator
to generate the high voltage back in the late 50's and early 60's.
You can find a manual on ebay. Heathkit Manual Capacitive Discharge Ignition
If you want a cheap pulse transformer they can be had from salvaged PC power
supplies. It takes a lot of fooling with them to find the windings that work.
A CD systems trigger with no delay.
BTW with AVR development board are you using?
Paul Lamar
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I just had a better idea.
Use an ABS sensor on the flywheel teeth and get a much higher frequency.
4000 pps at 400 RPM and 8.3 Khz at 8000 RPM. Now we are in the range of switching
power supplies found in PC. Much smaller transformers.
No 2nd gen CAS needed. Will work with any rotary 12A to RX8 that uses a starter.
Here are some typical PC power supply transformers and CD caps.
Paul Lamar
I was fooling with a transformer out of a PC power supply. I found a couple of
windings that seemed to work. 10 volts in pp gave 100 volt out pp.
This was at 20 Khz but it worked over a wide freq range.
Remove the primary, use larger wire and cut the number of windings by about 1.3rd.
Paul Lamar
I think I found a source for transformers. If the price is right I will get some and
build some CD's. These are so cheap we can use one per plug. I'll donate a set if you
are willing to test them. You must be in the U.S. so I can get there to witness the test.
Kevin, if you don't get yours to work I will be in Florida about Oct 1st. I might
have them done by then. Those 2nd gen Mazda coils make great CD coils when removed
from the igniter's.
In the past I tried to build CD systems but with out good results. I thought the HV
had to regulated. That was the main problem. I now realize that is not neccessary as
the outboard type are not regulated. Nor was the Heathkit for that matter. In other
words it is open loop. Here is an open loop CD system using a 555 oscillator at 68 Khz.
Paul Lamar
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