I found a circuit on the web that uses a 555 timer feeding to 2 transistors; the final one a NTE261. The NTE261 drives a step up transfromer used in a snowmobile. I am using it in an old hit-and-miss farm engine. The circuit did not work and I made some changes to the 2 transistors, and now it works fine.
My question is; from what I have read, and believe to know, the field collasping is producing a return voltage spike (actually a few spikes) back into the NTE 261 transistor. One is supposed to put a diode across a "coil" to prevent this, but when I do the circuit fails. The original web found circuit also did not have a diode, but it did have a 330 ohm resistor and LED from the collector to +6v. Would that path through the LED be enough to protect the NTE261??
Any thoughts would be helpfull.
Thanks Tom