I am working on a test fixture for 12VDC actuators. I am not certain the exact amperage, but I know it is well under 1amp. Somewhere around 300mA, I believe. The normal usage is to rotate a shaft which moves a plastic door. There are only two positions for the door: either end of full travel. The actuator is always powered, so when the door gets to its hard stop, the actuator is still powered, but stalls. I need to build a circuit that can test these actuators on a bench and run 100s of simulated cycles by driving for a set time and then switching polarity. The normal time for full travel is roughly 4 seconds. I would like to drive the actuators on the test bench for 15 seconds (most of the time would be against a hard stop). After 15 seconds of one direction, I need to reverse polarity and drive the other way for 15 seconds. This needs to repeat endlessly until I manually end the test. It will probably run for as long as a week, non stop. I believe my best bet for changing direction is through using an H-Bridge. But, Im not sure how setup the timer. Could anyone provide suggestions? I understand electrical circuits, but my electronics knowledge is less than basic. Thanks for any help.