The AB Electronics UK Knowledge Base provides support solutions, tutorials and troubleshooting guides.
The IO Pi Plus development board can drive up to 25mA per channel, but to drive higher loads, such as relays or some optoisolators, you will need to boost the output using a transistor or MOSFETs.
The circuit below shows how to operate a 5V coil relay using either a GPIO output from the Raspberry Pi or one of the output pins on the IO Pi and IO Pi Zero boards.
Driving optoisolators with the IO Pi Plus/Zero
Suppose you would like to connect an optoisolator to the IO Pi. In that case, you can remove the relay and protection diode and combine a series resistor in line with the optoisolator in place of the relay.
You can use our LED Calculator to find the correct series resistor for your optoisolator.
