Photon powered from a 12v relay module.... why is it working?


I’m using a 12v relay module from SainSmart ( ) with a pin expander MCP23007 and my Particle Photon.

The MCP23007 is powered thanks to the VIN from the Photon.

So you have : RELAY <—> MCP23007 <—> Particle Photon

I have discovered that I don’t need to power my Photon with the USB when the relay is powered by a 12v arrival. And everything is surprisingly working well…

Why ? Is it ok for the Photon on the long term ?

By the way, do you know any other relay module with 16 channels ?



@julienfoodgie, the relay board has its own 5v regulator which you are connecting to Vin of the Photon. This is why USB power is not required. :wink:

thanks for your quick answer.

What do you think about this relay board ? Are there any better (bigger) boards ?

Thanks :slight_smile:

@julienfoodgie, it looks good. However, ControlEverything has 24 and 32 relay boards that are I2C controlled if you are looking for more relays.

@peekay123 thanks for your help. I followed your advice and it works very well.

I bought an other 8 relays board and want to connect it to my master board but I don’t understand the address jumpers. Do you have any idea ? I’ve opened a topic on the matter:

This new discussion should be continued in only one thread (the new one).