The Arduino 4 Relays Shield is a solution for driving high power loads that cannot be controlled by Arduino's digital IOs, due to the current and voltage limits of the controller.
The Shield features four relays, each relay provides 2 pole changeover contacts (NO and NC); in order to increase the current limit of each output the 2 changeover contacts have been put in parallel. Four LEDs indicate the on/off state of each relay.
Operating Voltage |
5V |
Coil current consumption |
140 mA (with all releays on, about 35 mA each) |
Single pole chargeover contact maximum current |
@ 30 V DC 2A |
Maximum load voltage |
48 V |
Maximum switching capacity |
60 W |
The shield doesn't need external power: it will be provided by the base board, through the 5V and 3.3V pins of the Arduino board used as base.
The relays are controlled by the following Arduino board pins:
Relay 1 = Arduino pin 4
Relay 2 = Arduino pin 7
Relay 3 = Arduino pin 8
Relay 4 = Arduino pin 12
The shield features several TinkerKit input/output and communication interfaces. Connecting TinkerKit modules can simplify the creation of a project or a prototype.
The on-board connectors are :
The maximum length and width of the 4 Relays Shield PCB are 2.7 and 2.1 inches respectively. Four screw holes allow the Shield to be attached to a surface or case. Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the 100 mil spacing of the other pins.
The shield is compatible with all the Arduino boards, 5V and also 3.3V standards.
Schematic & Reference Design
EAGLE files: arduino-4-Relays-Shield-reference-design.zip
Schematic: arduino-4-Relays-Shield-schematic.pdf