This product is retired, please see here for a replacement.

Presentation

This is a relay shield for the Arduino MKR family of boards and other compatible boards with 3.3V I/O. In particular, it has been tested and used with the Arduino MKR Zero. The board must be plugged into the shield below, using the double 14 pin headers, as shown on the pictures above.

Relays are simple but very useful for IoT applications. As part of the Omzlo NoCAN IoT project, we needed a relay shield rated for 230V in a format that is compatible with the Arduino MKR family. Unfortunately, while there exists a relay shield for the Arduino MKR it is only rated for 125VAC maximum, which is not so convenient for countries that use 230VAC mains. So we decided to create our own!

This relay shield is rated for maximum 250V/10A (for a resistive load) and is activated through pin 0 of the Arduino MKR. A LED indicator turns on when the relay is closed (conducting). Connection to the relay is done through a 5.08mm 3-pin screw terminal block.

This shield comes alone, without an Arduino MKR board.

Documentation

The schematic is extremely simple:

The physical dimensions of the shield are summarised below.

The mount holes in the 4 corners of the shield are 3.2mm.

On a connected Arduino MKR Zero, closing the relay on is a simple as adding digitalWrite(0, HIGH); to your Arduino sketch, while opening the relay will require digitalWrite(0, LOW);. Pin 0 will need to be configured as output with pinMode(0, OUTPUT);.

Warning

This shield is a prototyping device. If you want to connect this relay shield to mains or any voltage above 30V, make sure you fully understand the associated risks and take all necessary security precautions. Please refer to a qualified electrician in case of doubt and follow local regulations where applicable.