For Sale - Four channel drive cards for GM-20 actuators. Each channel has adjustments for gain and offset. Requires +/- 12-18VDC, 2A power supply. Can deliver up to 3.5A per channel. Supplied with 0.5A fuses. These are great for optical tables, safety shutters, color flags and open loop XY scanning. Setup to pull GM-20 flag out for 0V signal and push flag in for 5V. Will setup for bipolar input as requested. Fast and bounce free. Can also be used to drive motors. Measures 3.25"x5.25". Discounted to $90 with free shipping in the US through 12/31/11. They are built and tested.