Electric ingiter for model rockets
Keep in mind that my device does NOT comply with any safety standards whatsoever and safety is based only on common sense. It should not be used for anything else but model rocket hobby.
I started of with a simple schematics as shown below. The idea was simple – to heat a thin wire with huge electrical current as quickly as possible. I used N-channel MOSFET with drain current rated at 80 A. Power source is 4S 5Ah LiPo battery rated at 20C which means that it’s capable of delivering 100A constantly.
Schematics of igniter
Nichrome wire with specific electrical resistance of 5 Ohm/m
Nominal voltage of the battery is 14.8V and lenght of the nichrome wire inside the igniter is about 5cm which gives us 0.25 Ohm and 60A when there’s just resistance of nichrome wire present. With the resistance of cables, connectors, battery’s internal resistance and internal drain-source resistance of mosfet an approximation of total resistance can be made which is about 1 Ohm.
MOSFET on heatsink with a push button and battery connectors
