Hi, I'm planning to add an 8 channel relay to the motor shield sitting on top of an Arduino Mega DCC++ system, should I use a 5V 8 channel module or should I use a 12V 8 channel module, assuming I've cut the VCC in on the Mega and supplying 12v power directly from the motor shield? Thanks, Kent
Each 5V relay will draw 70 mA (check for yours), if all are on that will make 560 mA. This is too much to be taken from the Arduino. So, it would be better to use a seperate supply, either 12V or even 5V for the relays (according to them). If you use the same supply as for the shield, just check that the common (-) can be tied together (no other elsewhere). The command of the 12V relays is done through opto couplers, so the 5V ouputs of the Mega will do.