External motor cut-off ,parallel circuit for pwhawk

Hello, i want to find a easy solution to stop motors with external circuit in parallel ,my idea is just to link pwm signal with mosfet or transistor to the ground , I wonder if it might not destroy the pixhawk , in piaxhawk 1 hardware there is 220 ohms resistor in series with the outputs , i can not find the pixhawak 4 detailed hardware ,it should be the same thing and it can work , I want your idea on the subject

Hello @Tarek-H

Why don’t you use Emergency Stop feature provided by Ardupilot? It would be the simplest way to do that and you wouldn’t need any kind of extra hardware:

https://ardupilot.org/copter/docs/common-auxiliary-functions.html

I can testify that the Motor Emergency Stop feature definitely works as planned.

If you really need some external device, you would probably need to use some circuit with a 74LS244 or similar to properly pass the PWM signals (or disable them). Your idea of shorting the PWM outputs to ground may work but would need testing.

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it is for a specific regulation, they ask for an independent parachute with an independent engine cut-off.
I have already designed and tested components (mux) which connect in series with the pwm output, it works well but if the component fails there is a big risk, I am thinking of a simpler solution and more reliable which connects in prallel and can be detached from the main circuit that’s where my idea comes from.

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