designed by David A. Johnson, P.E.
owns several coin operated telescopes. Their
problem is that the battery needs to be replaced every
few months. I needed to design a new circuit to control
the shutter. The solenoid used was too
Once the coin
was accepted and fell into the coin box, a motor would open the
shutter for 2 minutes. After those minutes had elapsed,
the motor would reverse direction and close the shutter.
The timer would allow only one coin at a time.