hi
i also fly model rockets, and also found the need to use multiple launch pads, a while ago i designed a circuit that allows me to send 6 seperate signals down a 2 core cable.
if this is of any interest to you pmme and ill send it to you, i have since moved over to 2.4ghz launch setup of which im still ironing out a few issues.
where in the world are you?? and what do you fly???
I came across this thread while searching for a way to launch bottle rockets off of my rc heli. I couldn't find anything i could use to make my quest easier so I moved on in further search. That's when i came across this. **broken link removed**
I remembered this thread and figured I'd share if this is something you're still looking for. I'll send it to you in a PM as well.
In the interest of safety, one thing you may wish to consider is that MOSFETs very often fail short circuit. It may be worth including LEDs to monitor each firing circuit for voltage to avert an unintended ignition at the launch pad. I myself have be flying model rockets for 20+ years and witnessed a launch pad accident involving serious burns.
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trident
Never seen a MOSFET fail as a Drain to Source short. The only way I've seen them fail is Gate to Source leakage (which keeps them OFF). Overtemperature usually melts the PCB solder connections, opening the circuit when the MOSFET falls off the board.
I would recomend using high current relays instead of MOSFETs, simply because the igniters can be hard to "Light" some times.
In the years we launched rockets we had the battery right at the pad and short heavy wires to the igniters. Relays will not usually fail shorted and provide a low resistance path to the igniters. IgnitersThey might be listed at 1 amp but with voltage drops you can get a lot of misfires. It is also nice to have a launch interlock key that can be removed and carried with any one working on the pad to prevent accidental launches.