The circuit of the figure consists of a motor timer that can delay drives for up to 15 minutes. Pressing S1 for a moment (which may be a reed-switch sensor, a limit switch or other), the circuit will trigger and the motor will run for a time determined by the potentiometer setting. The value of capacitor C2 will also determine the time and can be between 1 uF and 1 000 uF. With a potentiometer of 1 M ohm and a capacitor of 1 000 uF a maximum time of the order of 15 minutes is obtained. After this time the motor will automatically shut down and a new drive will wait for S1. The transistor must be fitted with a small heat radiator and it can accept equivalents.
