Remaining circuit 220Vac
This is a standard bathroom fan timer.







simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. A fan delay-off timer.


An "always-on" live feed is required for the timer.
Switching on SW1 lights the light and feeds the timer.
Switching off SW1 turns off the light and starts the off-delay timer.
The fan runs while the light is on and remains running for a set time after SW1 is switched off.