Dual Relay Bricklet


The Dual Relay Bricklet is discontinued and is no longer sold. The Industrial Dual Relay Bricklet is the recommended replacement.


  • Two relays to switch AC/DC devices
  • Switches up to 240VAC/10A and 30VDC/7A


The Dual Relay Bricklet can be used to extend the features of Bricks by two relays. Each relay has three terminals such that the terminal in the middle is electrically connected to the terminal left or right depending on the state. The state is visualized by a LED. The new hardware version 1.2 is equipped with extensive protection circuitry against interference of inductive load switching.

You can use this Bricklet to switch power supplies, motors, lamps, etc. Consider the maximum voltage and current.

If you want to switch inductive loads, please see: Inductive Load Switching.


Terminals and contacts are not insulated. If you want to switch higher voltages, consider to put the Dual Relay Bricklet in a casing. Touching the contacts is potentially life-threatening!

Technical Specifications

Property Value
Relay AZ943-1CH-5DE
Current Consumption 75mA (per Relay)
Maximum Voltage/Current
AC: 240V/10A
DC: 30V/7A
Dimensions (W x D x H) 45 x 45 x 25mm (1.77 x 1.77 x 0.98")
Weight 29g



Each relay has three connectors: A, SW and B. SW is connected to A or B depending on the switching state of the relay.

  • If the relay is switched off, then SW is connected to B
  • If the relay is switched on, then SW is connected to A
Dual Relay Bricklet, visualization of the switch

Test your Dual Relay Bricklet

To test a Dual Relay Bricklet you need to have Brick Daemon and Brick Viewer installed. Brick Daemon acts as a proxy between the USB interface of the Bricks and the API bindings. Brick Viewer connects to Brick Daemon. It helps to figure out basic information about the connected Bricks and Bricklets and allows to test them.

Connect the Dual Relay Bricklet to a Brick with a Bricklet Cable (see picture below).

Master Brick with connected Dual Relay Bricklet

If you connect the Brick to the PC over USB, you should see a new tab named "Dual Relay Bricklet" in the Brick Viewer after a moment. Select this tab. If everything went as expected the Brick Viewer should look as depicted below.

Dual Relay Bricklet in Brick Viewer

Play around with the two relay buttons, you should hear the relay switching when toggling the buttons. An LED indicates the current state of each relay.

After this test you can go on with writing your own application. See the Programming Interface section for the API of the Dual Relay Bricklet and examples in different programming languages.

Inductive Load Switching

Without external components the switching of inductive loads can cause interference in the system that can lead to malfunctions or destroyed components. Typical examples for inductive loads are motors and solenoids, but these problems can also occur when switching e.g. fluorescent lamps.

If you want to switch an inductive load you need external components, e.g. a varistor or a combination of a resistor and a capacitor parallel to the load.

More information about protection circuitries can be found here.


A laser-cut case for the Dual Relay Bricklet is available.

Case for Dual Relay Bricklet

The case of the Dual Relay Bricklet is delivered including cable ties for a cable relief and WAGO connecting clamps to join wires. The case is big enough to accommodate the cable relief as well as the WAGO clamps.

The internal construction can look as follows (with one as well as two relays connected)

Case for Dual Relay Bricklet with one relay connected Case for Dual Relay Bricklet with two relays connected

The protective conductor (brown) is switched with the Dual Relay Bricklet. The external conductor (green-yellow) and the neutral conductor (blue) are coupled with the WAGO connecting clamps.

It is important that the external conductor is longer then the other cables. This way it is assured that the external conductor will be pulled of at last if the cable relief is overstrained or defect. We recommend the following length for the cables and the stripping:

Recommended lengths

The assembly is easiest if you follow the following steps:

  • screw spacers to Bricklet
  • screw Bricklet to bottom plate with spacers
  • build up side plates (including cable relief)
  • plug side plates into bottom plate
  • add cabling and WAGO clamps
  • tie cable ties to cables
  • screw top plate to top spacers


Never work inside the case when components are carrying voltage!

The exact position of each part can be seen in the following exploded assembly drawing of the Dual Relay Bricklet case:

Exploded assembly drawing for Dual Relay Bricklet

Hint: There is a protective film on both sides of the plates, you have to remove it before assembly.

Programming Interface

See Programming Interface for a detailed description.

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