This board has two connectors, one on either side and a space for an optional third. Let's take a look!
- STEMMA connector - on the left side, the black connector is the STEMMA connector. Compatible with 3-pin JST STEMMA cables.
You can use any of these cables - they are JST PH 2.0mm connectors
- Red goes to 3 to 5V DC power (this is used to power the transistor that turns on the relay, not to the output of the relay)
- Black goes to power/signal ground on your microcontroller or device
- White goes to 3 to 5V signal. The signal is amplified on the relay board so it does not have to be a powerful pin
- Relay - Located in the center of the board.
- Terminal block - The connects for the relay are the white tubular thing at the far end of the PCB. You can poke wire into the holes, they will automatically grip onto wire that is 24AWG to 18AWG. Once you poke the wire in, give it a light pull to verify its clamped. To release the wire, use a thin screwdriver or pen to press on the button on the top while pulling the wire out.
This board has a single Signal pin (the white wire). Normally, the relay's COM pin is connected mechanically to the NC pin and the NO pin is disconnected.
When the Signal pin is pulled high, the relay switches and the internal switch changes so that the COM pin is mechanically connected to the NO pin and NC is then disconnected
- LED - Status LED, located below the STEMMA connector.
- Optional terminal block - Connect a 3-pin terminal block to this optional spot to add another switch