Powering a 5v relay with 12v?

I have a Sunfounder 2-channel relay board. It has a VCC voltage requirement of 5v. Has anyone ever used a 12v source to power it instead? How likely am I to damage the board?

I think you have a pretty good chance (of damaging it, that is). A 5v voltage regulator chip seems like a pretty obvious option.

Yeah, but this relay board might be powered by either 12v or 5v, depending on which device is turning it on. I already need a diode to isolate the sources. I was hoping to find a way to do this without adding a voltage regulator to the 12v trigger.

GoremanX:
Yeah, but this relay board might be powered by either 12v or 5v, depending on which device is turning it on. I already need a diode to isolate the sources. I was hoping to find a way to do this without adding a voltage regulator to the 12v trigger.

How many relays on the board? If it's only a small number you could use the 5v from your arduino.

12V will definitely damage the relay board. This 2 channel relay board requires about 200mA at 5V with both relays energized.

I suppose the simplest solution would be to use a 5W, 6.8V zener diode connected in series with 12V to drop it to 5.2V. The 1N5342B can supply 700mA max, it will dissipate about 1.4W with 200mA load.

Don't forget to remove the jumper and use JVCC for the 5.2V supply.

GoremanX:
Yeah, but this relay board might be powered by either 12v or 5v, depending on which device is turning it on. I already need a diode to isolate the sources. I was hoping to find a way to do this without adding a voltage regulator to the 12v trigger.

Hang on! Surely it will always be the arduino turning the relays on or off. Your other devices are supposed to be connected to the switch contacts of the relays.

How are you connecting this relay board.

Hi, can you post a circuit diagram of how you are going to connect the relay to the arduino and the load you will be using the relay to switch.

Picture of a hand drawn diagram would be fine.

Tom..... :slight_smile:

KenF:
Hang on! Surely it will always be the arduino turning the relays on or off.

Yes but that's not the supply to the coil. The page I found, shows a Vcc pin as the OP said which would be the 5V coil power, as well as IN1 and IN2 which is the Arduino signal.

The OP wants to substitute the 5V with 12V and it clearly says on the relays themselves (as distinct from the board), 5VDC.

JimboZA:
The OP wants to substitute the 5V with 12V and it clearly says on the relays themselves (as distinct from the board), 5VDC.

I understand that, BUT the coil voltage has NOTHING to do with what device the relay is driving. I think this is what is confusing the OP.

Yeah, I meant to add that bit too, that the switched side is the 250VAC or 30VDC is the other stuff it says on top of the relay. In fact I did type that, the Internet went off, the page timed out, and I typed it differently the next time.

Perhaps we need a recap, that there are 3 aspects to this:

  • 5V from an Arduino i/o pin to CONTROL the relay's switching
  • 5V from somewhere other than the Arduino to POWER the relay coil. The Arduino 5V output is not a good choice to provide power, since it probably can't provide enough current
  • Up to 30VDC or 250VAC SWITCHED by the relay to drive the load, whatever that is, like a motor or ....

So OP as KenF says, you need to clarify if the 12V is the power for the relay coil, or the power for the device being switched.

@OP,
You need to be more specific. Since you didn't post a schematic at least post a wiring list:
ie:
PS **ARDUINO ** **RELAY COIL ** LOAD
12V----------------------------------->12V
5V ----->5V------->5V