The relay board has 4 double pole relays and a power supply. This allows the board to be powered by either AC or DC. All the relay contacts are accessible for wiring from screw terminals. Four LEDs are fitted to the board. Each LED lights when its associated relay is energised. The power supply allows the relay board to be powered from either 12 to 16 volts AC or DC. The relays are rated for switching a current up to 5 amps.
The relays operate when "S" is connected to 0 volts. The terminals are arranged so that "C" is common "A" is normally closed and "B" is normally open. The number after the letter refers to the pole of the relay. The first relay has poles "1" and "2", the second "3" and "4", the third "5"and "6" and the fourth "7" and "8". If the top right "S" is connected to 0 volts the relay contacts will connect
"C3" to "B3"; and "C4" to "B4".
Disconnecting 0 volts would connect "C3" to "A3" and "C4" to "A4"
The Relay Board is also available with 2 double pole relays.