Single Channel Relay DIY Electronics Kit
Control AC devices using arduino

This listing is for an active-low single channel relay driver board module. There are four input pins:
5v - Connect 5v here to power the device
IN - A low signal must be applied to this pin to activate the relay.  Internally, this line is pulled to 5v.  When sunk to 0v-GND, the relay will activate.  Hence, active low.
Ground Symbol (Looks like an upside down T) - There are two of these pins, but you only realy need to use one.  These are your DC supply power ground pins.

When the relay is activated, the on board red 3mm LED turns on, and will stay on until the relay is deactivated.  There are four mounting holes; one in each corner.  The relay outputs are unfortunately not labelled, but the COMMON (CO) pin is in the middle, the NORMALLY CONNECTED-CLOSED (NC) pin is on the same side as the red LED, and the NORMALLY OPEN (NO) pin is on the same side as the single resistor.

If you have any questions, please do note hesitate to ask.

Size:
Length:  39mm
Width:  24mm
Height:  18mm