This is a simple circuit for the time delay circuit. This circuit is based on transistor as controller the circuit. This is the figure of the circuit;
The length of time the circuit stays on for depends on how long it takes for the stored electrical current to leak back into the circuit, keeping the transistor (and thus the entire circuit) energized. We have a resistor that is limiting the rate at which the capacitor can discharge. If we increase the value of that resistor, it will take the capacitor longer to discharge and so the cold starting circuit will stay energized for longer. Likewise, if we decrease the value of the resistor, the capacitor will discharge more quickly, and the circuit will operate for a shorter period of time.
