The ghost trap uses a servo and a 555 timer circuit to change between two preset positions. A servo has three leads, a positive, negative and a "signal" that can control the position by supplying a specific frequency. The higher the frequency, the further it rotates. I built this circuit: http://www.555-timer-circuits.com/image ... roller.gif
with the modification of having two resistors and a switch where the 100k potentiometer is between pins 7&8. One resistor sets the "open" position, the other the "closed" position. You will have to experiment with the resistor values to find the correct "throw" for your particular linkage on the doors. The linkage I used was a stiff cable similar to one from a bicycle braking system that runs through tubes and pushes/pulls the doors open/closed. you could use two cables, both connected to the servo, or a "Y" shaped one that splits under the mirrored bottom like I did. The servo is mounted in the front under the display, and operates the hinges in the rear. The pedal contains the switch mechanism and the two resistors. Press it once, resistor 1 is active, press again and it switches to #2. The main power switch in the rear turns it completely off. Batteries are mounted in the rear. The center section is removable like the movie prop, with a 3 prong plug connecting it electrically to the base, and hard drive magnets and washers to keep it from falling out. The mirrored bottom is a cut up laserdisc that reflects white leds installed in clear straws up under the top by the doors.