Difference JD-Vcc and RVcc on Relay module?

Using Arduino General Electronics
1

Hi all,

I'm wondering what the difference is between the RVcc pin on a relay module

see image (in between Vcc and Gnd)

and JD-Vcc? see image (next to Vcc)

I am trying to connect a 12V motor to my relay module, but all tutorials I find are tutorials with the 2nd type of relay module, while I have the 1st one. So I want to be sure the two pins mean the same before blowing up my module.

I'm sorry if this is a dumb question, I am not quite professional on this.

Thanks!

2

According to this they're the same thing: with the jumper off, relay's own 5V goes on RVcc ala JD-Vcc on the other make.

3

Always worth getting the multimeter out and checking. Normally you only need to connect
the Arduino +5v to the relevant Vcc to drive the opto-isolators, don't connect the grounds or
the jumper and you have a fully isolated system, but you require a separate 5V or 6V supply.

Bridge the jumper and connect grounds and you don't need the other supply and the relay
coils are not isolated. (ie the Arduino 5V is supplying the relay coils and seeing the noise
they generate).

Eitherway the relay contacts are isolated, but heavy noise from the contacts can be transmitted
to the relay windings, the extra level of opto-isolation really helps in that situation - just keep all
the Arduino wiring well away from the load wiring too.

4