looking for GM smartcoil driver circuit...

[Bruce Plecan]

| I have been investigating these...
| You have to raise the control line over 2.7V to 'arm' the coil.
| It then fires when the control line falls below 2.5V _OR_
| 0.1 second later, whichever comes first.

0.1 sec later than what?.
Meaning it fires a 0.1 sec after raising to 2.7v?.
Sorry, I'm confused here.

| So, toggling between 5V and ground works fine.  Input impedance is
| high, over 10k, so you don't do any harm connecting directly to 5V.
| I have driven them using an opto isolator (4N35), collector to
| 5V, emitter to resistor to coil, resistor to ground too.  I also
| tried forming a darlington with the opto and a generic NPN in a
| similar config.  Both methods work fine on the bench.
| Other things that I noticed were that it takes approximately
| 25 uS between grounding the control line and the spark and
| you don't get a very good spark with the control line high
| for only 1mS.

Just curious was this with a battery type power supply, or an amperage
limited test bench power supply?.   Could there be a coil "charge" sensor
item?.
Grumpy
|
| As for connectors, I heard that wires that fit in some Bosch
| distributor caps work.  I have yet to verify this though.
|
| If I get chance, I'll check my driver circuits and post them
| tomorrow.
|
| Orin.
|