Just want to confirm if pixhawks relays will do 5v or not


So the arducopter documentation states that the relays can switch between 0v, 3.3v, and 5v. Ive gotten 3.3v out, but i haven’t seen any information on how to get 5v out on the signal/switch/relay wire. I think the 5v was a misunderstanding or a typo, just want to confirm if there’s a way to get the relay to do 5 volts or not.

A relay i got was supposed to work with 3v but either the voltage drop or something else is faulty because the relay doesn’t work. I’ve tested 3.3v at the relay, but it doesn’t switch the relay while others have had success at 3v. 5v works fine though.

It’s 3.3V with a “standard” Pixhawk. But there are so many Pixhawk variants perhaps some are at 5V.

Don’t put a relay directly to the output of pixhawk.
The output of a servo channel can drive max 50mA. Normally relays need more than that.
Use a switching transistor and if possible an optocoupler to drive your relay.


A solid state relay i have works fine with the 50 mA signal, but these other relays we got utilize the usual electromagnetic coils so they need a bit more juice. Thanks for the octocoupler idea by the way that’s smart.

We’re just using the relay to short two signal terminals to “press” a button. From what I understand about octocouplers, could i use the octocoupler as the relay instead?

@dkemxr so the 5v is just in case a different variant uses 5v logic instead of 3.3v for the signal pins then? It’s not something you can just change in parameters

Yes, that’s my understanding.

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It depends on how the button is polled, but many time a simple optocoupler, or an SSR optocoupler will work just nice. Avoid zero crossing ones, they will not work.

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