Tuesday, April 7, 2009

Magic Smoke

Progress is still crawling along at glacial speeds due to my day job. I have flowed propellants through the motor, discovered some leaks, repaired leaks, and reassembled. The motor is on the stand once again and awaiting time for testing.

Tonight while I was testing the ignition system to see if the trigger rate had any effect on spark quality, I was reminded of what I learned in EE lab - semiconductors run on Magic Smoke. If you let the smoke out, they don't work anymore.

I'm using an ignition module designed for small R/C aircraft engines from CH Ignitions.

After being triggered at 200Hz for 10 minutes or so, it suddenly stopped sparking. Because it was warm to the touch, I decided I would disassemble it and confirm that I had let the smoke out.

200 Hz corresponds to about 24,000 RPM in a single cylinder 4 stroke, so its not great surprise that it quit on me. I've also not lost much time because I originally (2 years ago?) bought two modules. And that reminds me of one of the things I've learned working on these projects - Always buy at least one more than you think you'll need.