Here's an idea - the power to all the "moving" parts are controlled
through opto-coupled solid state relays (Vishay VO14624AT). Assuming I
trust the MOSFET side of the SSR against inadvertent switching, all I
need to do is switch off the +3.3V that goes to the LED side of the
relays of interest:
Fuel solenoid
GOX solenoid
CDI module
Servo power
Recovery actuator motor
For added safety, since the power for the CDI and solenoids is
off-board, I can turn those power supplies off when servicing the
vehicle. Aircraft Spruce has some inexpensive mil-spec switches (Otto
T3) series that should work for the onboard +3.3V power for the SSRs.
-Bob
