Delay off delay circuit

[remzy]

Hello everyone. I want to make a delay off circuit to use in my car's dome light because right now it turns off when I close the door and I want it to stay on for about 15 seconds after I close the door. I found a circuit which works but the problem is that it is activated by a positive voltage, and there is no way to activate it because my car's door switch switches a negative voltage, i think they've done it that way because they only need one wire to dome light instead of two if it was switching positive voltage. Is there a way to activate this circuit with a negative signal-voltage? Here is the circuit:

 

[CDRIVE]

A 555 Timer will trigger on the negative going edge and provides enough drive current to drive a small relay coil.
However, before you go through the work of brewing your own check out Ebay under "Delay Timers". The Chinese can sell you a complete timer with 'on board relay' for less than you could make it yourself.

Chris

 

[73's de Edd]

Sir remzy . . . . .
If your vehicle is using the typical dome light circuitry shown, which uses a grounding switch in each door . . .then . . .the second circuit using 9 common parts should give an all solid state solution.
In final evaluating, if more delay time before dimming is needed increase the circled capacitors value.

Le Schematique . . . . .



73's de Edd

 

[remzy]

Sir remzy . . . . .
If your vehicle is using the typical dome light circuitry shown, which uses a grounding switch in each door . . .then . . .the second circuit using 9 common parts should give an all solid state solution.
In final evaluating, if more delay time before dimming is needed increase the circled capacitors value.

Le Schematique . . . . .

View attachment 36060

73's de Edd

Thanks for the circuit. I will try it out. There might be issues because I've modified my dome light from incandescent bulb to LED's.

 

[73's de Edd]

Sir remzy . . . . .

Should be no problem, if about the same or EXPECTEDLY pulling much less power consumption, the T2 "electronic switch" should then be able to loaf.

73's de Edd