Simple Relay Shield v 2.0

relay shield

A minor bump for one of our little open source Arduino add-ons. The Simple Relay Shield is an easy to use single-relay board that does one thing, and does it well: It adds a beefy little mechanical relay to an Arduino, which you control through pin Digital 4.

relay shield

Version 2.0 adds the ability — by popular request — to control it from a pin other than D4. Solder the jumper in the normal way (in location JP), and it works on pin D4. Hook it up to any other digital pin, say to D7, and now you have a relay on that pin. The Simple Relay Shield is available as a complete soldering kit or as a bare PCB, and you can find documentation on our wiki.

Access Point Garage Door Opener

Over at Dead, too much lettuce., Scott built an Access Point garage door opener with a Raspberry Pi, an Arduino, and our Simple Relay Shield.

I bike to work. Bikes live in the garage. But with only 2 remotes, I could not keep one in my bag all the time to be able to get to the bike. So a new option had to be created. Most people would have bought a new remote…

A Simple Relay Shield for Arduino

Relay Shield

Introducing our newest kit: the Evil Mad Scientist Simple Relay Shield for Arduino.

It’s a dead-simple single-purpose low-cost mechanical relay board, with a single low-power SPDT relay that can switch moderate loads of up to 5 A, AC or DC.

Relay Shield

The relay is controlled by digital line 4— and that’s well labeled, too.

No library is needed. For a demo, just open the Arduino “Blink” example sketch and change the LED pin to 4.   When output Digital 4 on your Arduino is low, the relay is in the “normal” state: the “Common” pin of the screw terminal is connected to the N.C. (“Normally Closed”) pin of the screw terminal.

When output Digital 4 goes high, the “Coil On?” LED will light up and the relay enters (for lack of a better term— suggestions welcome!) the “abnormal” state, and the Common pin is instead connected to the N.O. (“Normally Open”) pin of the screw terminal.

Relay Shield

One of the main concerns about using higher voltages and/or currents on an Arduino shield is that you potentially have these things wired awfully close to things sticking up from your Arduino board, like the microcontroller itself or the USB connector.  If you sometimes would like a little more breathing room, a good solution is to add the insulator shield Googly Eye Shield between the two.

Relay Shield

The Simple Relay Shield circuit board is a standard 2-layer, 1/16″ thick FR-4 PCB, but with highly-visible yellow soldermask.  While it is (yes) very simple, the Simple Relay Shield is an open source hardware project. The circuit board is designed in gEDA, and the design files are available for download at the Evil Mad Science Wiki.

The Simple Relay Shield is available now at Evil Mad Science.