Someone hed been trying to figue out how to do an auto dimming dome light like they have in the new cars and I had an idea and was wondering if anyone thought it woulr work. How about installing a second bulb in the dome light housing that would be connected to a capacitor, the capacitor could be charged by the power wire to the dome light when the door is opened then when the door is closed and the main buld goes out, the secondary bulb would remain lit until the charge in the capacitor was drained. Does this sound feasible?

I would probably investigate a retained power relay circuit with the ignition or door lock cutting off the retained power.

Borrowed from another site:

Dome light dimmer for Cars -designed by Naveen P N

This unique circuit makes your dome light look cool. Usually when the car door is closed, the dome light just goes OFF. With this circuit, you can have our dome light fade slowly in brightness and finally go OFF. This slow dimming of the light gives a very good feeling at night. It looks very romantic!
The circuit can be explained as follows: When the car door is open, the push to off switch of the door is ON and hence it charges the 22uF capacitor fully. The opamp is acting as a voltage follower and its output is same as the voltage across the capacitor, which is 12V when the capacitor is fully charged. Due to a high voltage at the output of the IC, the transistor saturates, turning ON the bulb to full brightness.

Now when the door is closed, the door switch is pushed in and hence the switch goes OFF. When the switch is OFF, the capacitor starts discharging slowly through VR1 and the 10K resistor and the voltage across it decreases slowly. Hence at the output of IC 741 also the voltage decreases gradually, hence decreasing the base current to the transistor. This produces a slowly decreasing current through the bulb and the bulb fades out and finally when the capacitor is fully discharged, the bulb goes OFF.

After building the circuit, with the push-to-off switch in ON position (not pushed in) i.e. the car door open, adjust the preset VR2 to the required initial brightness of the bulb. Then push the switch in to turn it OFF(or close the door) and adjust VR1 for the time to bring the bulb from full brightness to OFF.
I would suggest you set VR1 and VR2 to their maximum values.
Note: 2N3055 power transistor needs proper heat sink.
Click here for circuit diagram.


http://www.electronic-circuits-diagrams.com/carsimages/3.gif

This is very interesting....Does anyone think this theory would work simply by installing a 22uf cap inline with the dome lamp hot lead? I know it wouldn't work at the pin switch due to the fact that the door switch merely completes the ground....wait, i think i may have just answered my own question....lol. Power must ALWAYS exist at the dome assembly...Right / Wrong?

Someone hed been trying to figue out how to do an auto dimming dome light like they have in the new cars and I had an idea and was wondering if anyone thought it woulr work.
No need for a second bulb. You can buy a kit that will do it all for you. Quoted from the http://www.americanautowire.com/products/#Product2
website

American Autowire is pleased to introduce the Courtesy Light Delay Module; the newest addition to the extensive product line. The Courtesy Light Delay Module allows the courtesy light to remain illuminated for a user defined amount of time or until the ignition is switched on. At the end of the timed delay,the courtesy light will gradually fade to dark.The Courtesy Light Delay Module has only three (3) wire connections making installation simple. The connections consist of 1 (one) ground; 1 (one) courtesy ground (for lighting); and 1 (one) wire to accessory power. The Courtesy Light Delay Module is fully adjustable from 17 to 80 seconds allowing the user to customize their preferred delay time. With the addition of this new accessory for Street Rodders, American Autowire maintains their rank in the marketplace as the number one manufacturer of Street Rod accessories and OEM reproduction harnesses.

Part number 500777
List Price $59.00

Yeah I knew someone made a kit for it, but I was trying to come up with a more cost effective (cheap) method. :)

Ya know,

I designed a circuit a while back, it doesn't cost much at all, rivals actual factory GM units and is easy install. But it seems like everytime I post a circuit, someone posts a link to a ready-to-go jobbie or gripes that it involves too much electronics.

BTW, mine is a helluva simpler than the ones you find on the internet, no 555 timers, op-amps, all that b.s. does is more to go wrong in the temperature extremes of a car

Ya know,

I designed a circuit a while back, it doesn't cost much at all, rivals actual factory GM units and is easy install. But it seems like everytime I post a circuit, someone posts a link to a ready-to-go jobbie or gripes that it involves too much electronics.

BTW, mine is a helluva simpler than the ones you find on the internet, no 555 timers, op-amps, all that b.s. does is more to go wrong in the temperature extremes of a car

I'd be interested in seeing your circuit post; i'm always interested in new ideas!

my 94 LHS has that feature, and i always think the door jam switch is bad and the battery is going to go dead..
i've been trying to figure out a way to make the light just go off when i close the damn door..
maybe there's a fuse i can pull or something.

I'm curious as to why anyone would want an "auto dimming dome light "
What is the purpose of it?
:confused:

I'm curious as to why anyone would want an "auto dimming dome light "
What is the purpose of it?
:confused:

"Hey guys, bet you don't have this"

I just thought it would be different to have one in an old muscle car, just personal preference. I would love to see anything that anyone else has come up with?

I'm curious as to why anyone would want an "auto dimming dome light "
What is the purpose of it?
:confused:

Dean-

Here's a great example...

Let's say it's cold or rainy or nasty outside, you quickly fumble for your keys to unlock the car door. You quickly jump inside and slam the door. You drop your keys or don't have the ignition key handy to put right in the ignition. With an auto dimming "theater lighting" dome light, the door is shut, but you still have the dome light on giving you time before it gradually fades away.

Another example is let's say your in a parking lot, and you just locked up the car and are walking away...wait, what's that? Did I forget my favorite CD on the seat? You quickly glance back, and although it's dark out, there's still time to check the interior of the car before the dome light goes completely out.


I hope I can find my schematic, I drew one up about 7 years ago! It also mimic's GM's circuit, where you turn the ignition on and the light quickly dims out

Dean-

Here's a great example...

Let's say it's cold or rainy or nasty outside, you quickly fumble for your keys to unlock the car door. You quickly jump inside and slam the door. You drop your keys or don't have the ignition key handy to put right in the ignition. With an auto dimming "theater lighting" dome light, the door is shut, but you still have the dome light on giving you time before it gradually fades away.

Another example is let's say your in a parking lot, and you just locked up the car and are walking away...wait, what's that? Did I forget my favorite CD on the seat? You quickly glance back, and although it's dark out, there's still time to check the interior of the car before the dome light goes completely out.


I hope I can find my schematic, I drew one up about 7 years ago! It also mimic's GM's circuit, where you turn the ignition on and the light quickly dims out

well, i would counter that if you need some light to find your keys when yu drop them in the dark car, you could always give the headlight switch a quick twist to the left to turn the dome lights on..

and as for the second example- why would it matter if your favorite cd is laying on the seat? you did remember to lock the doors, right?
or is your favorite cd "Celine Dions greatest love anthems", and you don't want anyone to walk by and see it? in that case, i'd think you'd want the light to go off as fast as possible so no one can accidentally see it..

...so...anyone got an easy schematic?:D

no schematic, but I got this celine dion cd i swiped from Derrick! no wonder he didn't want an auto-dimming dome light! hehe j/k

hey Coppertop I hope you find the schematic. I'd sure like to see it.

I wonder how easy it would be to adjust the delay on the dome light. I like to know that the doors shut all the way and sometimes I don't feel like waiting for the light to dim. I don't have far to go to get in the house after I shut the door.

dammit.. i was looking for that CD..