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Product Information

Highlights

• Can switch loads of up to 30VDC or 127VAC
• Current capacity of 3A for the normally close contact and 5A for the normally open contact
• 4 options for the output pin to use, selectable by manual jumpers, and 7 additional pins selectable by solder jumpers
• Operates with 5V or 3.3V in the control signal
• Transistor-based control, minimizing the current that needs to be provided by the microcontroller pin
• Integrated voltage regulator, avoiding extra burden on the Arduino voltage regulator
• LED indicating if the relay is on or off

CAUTION

Only connect this module directly to AC grid power if you already have prior experience with mains AC circuits, and carefully follow the safety recommendations describer at the bottom of this page. Misuse of this module might cause ELECTRIC SHOCK and FIRE. We do not recommend using the Relay Nanoshield in 220V applications (in this case, look for the Triac Nanoshield).

Description

The Relay Nanoshield is the most versatile of the actuator Nanoshields, because it can be user to switch AC or DC loads, and also has both normally open and normally closed contacts. Depending on the connections used, this allows a device to be turned on even when the Relay Nanoshield is not supplied with power.

The activation the relay is done with an I/O pin from the Arduino, going through a transistor to minimize the current provided by the I/O pin. There are 4 options to use for the I/O pin (D3#, D5#, D6# e D9#), which can be easily selected using jumpers on the board. In case these four options are not enough, there are 7 more options that can be selected by solder jumpers at the bottom side of the board (D2, D4, A1, A2, A3, A4 e A5). The relay is activated when there is a high logic level on the corresponding I/O pin (keeping contacts C e NA closed), and deactivated when the there is a low logic level on the pin (keeping contacts C and NF closed).

Relays usually need a relatively high current (between 70mA and 120mA) to drive their coils during switching, and this can cause an overload in the Arduino internal voltage regulator in case it is the source of all this current – and the problem is aggravated if you need to use two or more relays simultaneously. Because of that, we included an integrated voltage regulator for each Relay Nanoshield, and in this case it doesn't add any extra load on the Arduino voltage regulator, allowing you to use many modules simultaneously without any overheating problems.

The switching of a relay is done by mechanical contacts, hence it is slower than solid state components like transistors and triacs. For that reason, the relay is not recommended for applications where a fast load switching is needed, like light dimmers and motor speed control, for example (for these applications, check the Triac and Mosfet Nanoshields). However, a mechanical contact has a very low electrical resistance and heat dissipation, allowing switching of high currents with a small relay and little heating. Other advantages of using a relay are the isolation between the control signal and the output contacts, and the possibility of using it either on the low side mode or in the high side mode.