Attach this board to the Simplified I/O Interface Board
Use nine pieces of hookup wire (or a piece of ribbon cable) to connect corresponding points on the I/O Demonstration Board to the Relay Sub Board. Connect 12 volts DC (smoothed) to the power input points on the I/O Demonstration Board. Solder in as many relays as you intend to use, each with its associated LED, resistor and 1N914 signal diode.
The board is now designed so that it may be cut in two to make two separate boards, each with four relays. This should be more than adequate for most purposes.
8 (or less) 12 volt SPDT relays
8 x 3mm red LEDs
8 x 560 ohm 1/4 watt carbon resistors
8 x 1N914 (or similar) diodes
1 x PCB Relay Sub Board
Source: Electronics Lab