I'm looking into making a little circuit that will turn my headlights off shortly after i have turned the ignition off, don't ask why I want to do this, or what is the use.....
Its because I want to.

so far i have found this



R1______________4K7 1/4W Resistor

R2,R3___________1K 1/4W Resistors

C1____________100Î…F 25V Electrolytic Capacitor (See Notes)

D1___________1N4002 100V 1A Diode

Q1____________BC547 45V 100mA NPN Transistor

Q2____________BC327 45V 800mA PNP Transistor

P1_____________SPST Pushbutton

RL1___________Relay with SPDT 10A min. switch

Coil Voltage 12V. Coil resistance 150-600 Ohms

but this will leave the lights on for about 1 minute 30, im looking for around 30 seconds, i know the delay depends on C1 and R1. I am unsure to what values i would need to change these to get a ~30 sec delay.

The other thing i wanted to know would it be possible to just remove the push button, so that the lights would always have the delay every time you turned the ignition off.

 

I would get a breadboard and mock it all up then change out C1 to fine tune the delay. If you need to know more, just PM me.

 

i would just BUY a control unit

http://cgi.ebay.com/DEI-545T-NITELIT...QQcmdZViewItem

i instaled them on my civic awhile back... they work great! never have to mess with your headlight controls again! hook it up thru your alarm system
it even has a DRIVING light feature BUT of course i cut that wire inside the unit cause those look bad.LOL

 

yeh i could buy one, but i want to make one, i am just going to take windcalmers advise, and fine tune it.... if anyone else knows what might be a good value, or a calculation i could use to figure it out...