Slightly over volting relay board

My project uses a typical 5v opto / relay board designed for arduino and the like. What would be the likelihood of damage to the relay board if I used a 6v supply vs 5v?

I ask because my project also illuminates 6v #44 bulbs and it would be much easier and compact if all the auxiliary components could share one isolated (from the arduino) power supply. Itd be a pain in the butt to have both a separate 6v and 5v supply and the bulbs are just a bit too dim on 5 volts.

You should be OK. If you are worried, look-up the manufacturer's datasheet for the relay and it should list a maximum coil voltage. There will also be a slight voltage loss across the relay driver circuit.

If you think that the 6V might be too much for the relay coils, you could put a silicon rectifier diode (1N400x) in series between the 6V source and JD-Vcc (relay supply). The diode will drop 0.6 to 0.7V.

opto relay 2.jpg

Thanks!

Why can’t you get 5V from the Arduino? It’s usually separate from the relay side.

aarg:
Why can’t you get 5V from the Arduino? It’s usually separate from the relay side.

Please don’t suggest to power the relays from the Arduino’s 5V pin…

wvmarle:
Please don't suggest to power the relays from the Arduino's 5V pin...

I didn't. Many relay boards have separate supply connections for the relays and the interface logic.

OP was asking about power supply to the board being 6V, not the signals.

wvmarle:
OP was asking about power supply to the board being 6V, not the signals.

Sorry, yes you are right about that. Arduino should not power relays.

However, driving a relay can be done via a buffer transistor which will drop .6V. Job done I'd say!

AJLElectronics:
However, driving a relay can be done via a buffer transistor which will drop .6V. Job done I'd say!

Most transistors don't drop that much (0.2-0.3V is normal for a BJT, of course less for a MOSFET). And such a transistor is required anyway.
Anyway, not likely the relay will work much different at 5V or 6V. It's not that critical.

Why are you using a relay to switch power for a small 6v light bulb? Just use some small MOSFETs directly!