This is a must for driving any circuits over 20mA.  TTL logic outputs from the OOPic or basic stamp, PIC, etc do not have the capacity to drive much more than an LED.  This board allows you to use your TTL outputs to pull in the relays.  This board is set up to drive a load forward and reverse.  Close the the single pole relay and the load goes one way, close both relays and the load reverse, the load is off when not relays are pulled in.   It also include travel limit switch inputs to stop the motor/load when the limit is reached.  There are two limits, one for each direction.   If you don't want to use the limits, just jumper them.   The circuit also has inductive load transient suppression which occurs when driving such things as coils on relays. 

The board has a status LED which will light with a TTL (+5VDC) logic input.  The board relays are rated at 8A@120VAC.    A 5V power source is required to drive the relays.  Another input voltage is required to drive the motor/load.

If you want screw terminals as pictured, you must select that addition below, else you can solder your wires right into the holes on the PCB.

These kits come unassembled, but you can opt for assembly if you wish.  All the components are on the top side, and the boards are spaced out to make assembly as easy as possible.  Click on the images to view the board in detail.

For assembly and operation instructions follow this link.(~1.5MB)

This is a Relay circuit driven by TTL singles.