# Photon powered from a 12v relay module.... why is it working?
**URL:** https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898
**Category:** Hardware
**Created:** [September 8, 2017, 11:04am UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898 "2017-09-08T11:04:56Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@julienfoodgie](https://community.particle.io/u/julienfoodgie)
#### Post date: [September 8, 2017, 11:04am UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898/1 "2017-09-08T11:04:56Z")
Hello,
I’m using a 12v relay module from SainSmart ( [https://www.sainsmart.com/collections/relays/products/16-channel-12v-relay-module](https://www.sainsmart.com/collections/relays/products/16-channel-12v-relay-module) ) 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 ?
Thanks
Julien
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### Author:  [@peekay123](https://community.particle.io/u/peekay123)
#### Post date: [September 8, 2017, 12:23pm UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898/2 "2017-09-08T12:23:36Z")
@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. 😉
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### Author:  [@julienfoodgie](https://community.particle.io/u/julienfoodgie)
#### Post date: [September 8, 2017, 2:04pm UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898/3 "2017-09-08T14:04:25Z")
thanks for your quick answer.
What do you think about this relay board ? Are there any better (bigger) boards ?
Thanks 🙂
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### Author:  [@peekay123](https://community.particle.io/u/peekay123)
#### Post date: [September 8, 2017, 2:14pm UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898/4 "2017-09-08T14:14:13Z")
@julienfoodgie, it looks good. However, ControlEverything has 24 and 32 relay boards that are I2C controlled if you are looking for more relays.
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### Author:  [@julienfoodgie](https://community.particle.io/u/julienfoodgie)
#### Post date: [October 9, 2017, 10:23am UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898/5 "2017-10-09T10:23:46Z")
@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:
> [@I2C relays. How to set the address with jumpers?](https://community.particle.io/t/i2c-relays-how-to-set-the-address-with-jumpers/36595):
>
> Hey I bought a 32 relays board on ControlEverything: [https://shop.controleverything.com/products/32-channel-relay-controller-i2c](https://shop.controleverything.com/products/32-channel-relay-controller-i2c) It works great but I needed 8 more relays, so I bought [https://shop.controleverything.com/collections/relay-controller/products/8-channel-relay-controller-i2c](https://shop.controleverything.com/collections/relay-controller/products/8-channel-relay-controller-i2c) My particle is on the 32 relays and it’s connected to the 8 relays board with I2C connectors. But how can I set up the address of the 8 relays board ? I don’t understand how address jumpers work. I’m using th…
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### Author:  [@ScruffR](https://community.particle.io/u/ScruffR)
#### Post date: [October 9, 2017, 3:55pm UTC](https://community.particle.io/t/photon-powered-from-a-12v-relay-module-why-is-it-working/35898/6 "2017-10-09T15:55:25Z")
This new discussion should be continued in only _one_ thread (the new one).