[FRC4ME]

Originally Posted by Al Skierkiewicz

FRC,
You should do some investigation into pullup resistors. The input circuit of the Spike is a opto isolator so a pullup to 5 volts (or 12) would set the relay in one direction and a short to the common terminal would turn off the opto isolator and set the Spike for the other direction.

Originally Posted by Don Rotolo

To amplify on Al's remarks: You do not need a double-pole switch to switch between 0 and 1 (if that is your intent): A single pole will do fine.

To wire this, simply connect one side of the switch to ground and the other side to the spike input. Also on the other side connect a 10,000 Ohm resistor (1/8 or 1/4 watt would be fine) to your voltage source (5V if you want to control a spike).

When the switch is closed the spike sees ground (as you would expect). The minimal current flowing through the "pull up" resistor will not affect this. When the switch is opened, the voltage source will appear on the 'spike' side of the switch. This happens because the input resistance (impedance, actually) of the spike is several orders of magnitude greater than 10,000 Ohms.

This is how these things are done. Good luck.

Thanks for the info. This makes me think of using the red light sensors - another component we have far too many of - to read "punch cards" of sorts containing the input values. I assume the same pull-up configuration would have no problems working with an NPN transistor triggered by a sensor, right?