Timer Relay - a 555 based power timing calculation

[lanz]

power-off timer 555

Hi guys i need a timer relay for my car.
I already browse the forum but still confused.
I need a 555 based power-on and power-off time delay relay(separated circuit).
The time must be adjustable and i need a regulated power supply for the circuit.
I also need to know how to calculate the timing of 555.
I know its depend on RC,but i dono how to calculate.
If got separated power-on and power-off time delay relay circuit picture,it will be easy for me to understand.

 

[Tahmid]

Timer Relay

Hi,
In the net, you can search the 555 timer tutorial of Tony van Roon. It is clearly mentioned there and you can be clear about 555 Timer.
Thanks.