It’s often necessary to switch power to a device that requires a current of several amps in order to drive it. The problem is, the device that’s required to do the switching may only be capable of supplying just a few milliamps. Such a circuit might be capable of switching on a LED but that’s about all.

The way around this problem is to use a relay with heavy-duty contacts to switch the power. However, your electronic switching circuit may not even have sufficient power to drive a relay coil – at least not directly.

This DC Relay Switch board is the answer to that type of situation. It utilises a heavy-duty relay with 30A contacts, runs from a 12V supply and requires just 400mA of signal to trigger the relay. That’s made possible by using an optocoupler and some simple electronic circuitry to drive the relay.

What’s more, the input trigger signal does not have to be ground referenced. This means that you can drive the relay board from just about any DC signal, whether it normally sits at around 12V, 5V or 0V. It can even be driven by low-voltage AC or by a signal that is rapidly switching on and off.