Been working a bit on the backpack poofer in the lead up to the burn, the electronics of which have been surprisingly hairy. Turns out, dealing with two high power loads (electric ignitor and valve both take 3A) at different voltages (5V and 12V respectively) is a bit trickier than I thought. A few interesting notes:
- Was getting frustrating hard-to-reproduce failures of the microcontroller after actuating the spark gap ignitor. Turns out that sucker puts out a LOT of electromagnetic interference. It was mounted near the Arduino. At the advice of a friend, I moved the ignitor up to the top of the gas exhaust, and ran the 5V line up to it, instead of running the high voltage from the backpack all the way to the top. This got rid of the problems, by creating a much shorter line, and separating the ignitor, which was probably putting out a lot of juice. Working with digital electronics gives you the false impression of modularity. Analog high power electronics puncture that balloon quickly.
- The ignitor is very high voltage at up to 3A. Because the microcontroller was acting up intermittently, I thought it was off when I unplugged the ignitor and had both of the (insulated) ends of the plugs in my hands when it suddenly actuated. I thereby became the spark gap. I was dropped to the floor cursing and screaming bloody murder, but there was no permanent damage. Fun with electricity!