If you dont know what "opera lighting/dimming" is... its the GM term (so im told) for when you open and close your door, your dome light stays on for a little bit, then dimes out...It is very easy to hook up, but the hardest part is finding the right size capacitor. i was just wondering if anyone has ever tried this before and what size capacitor they used.... or any suggestions on what size capacitor i should start with... if anyone wants to try it, just go to radioshack, and buy a bunch of capacitors..Than determine your power wire going to your dome light, then hook the capacitor up in series. then turn the light on, close the door....and see what happens...adjust the amount of time the light is on by the size of the capacitor (bigger for longer, smaller for shorter)

 

ttt

 

you can find out by looking at the dome light of a car that has it equiped. there will be a small capacitor attached to the wireing.

keep in mined that all you need is a small capacitor. were not trying to light the dome light for 10 min after the door is shut.

thanks
anthony

 

my wife's cavalier has it, and I absolutley hate it. If it's a part that I can just take out, I will give it to you if it's easy to remove and you tell me where it is

 

i would go look at a car that has one but i dont know exactly where it is gonna be located, and i dont want to tear apart anything on that car. ill just start small and see what happens.

 

the theater dimming feature is integrated into the body control module.

 

The capacitor idea will not work because 3'rd gens have a negative trigger interior light switch.

https://www.thirdgen.org/techbb2/sho...threadid=13581

 

The manual for my 85 IROC claims that the car has this feature, but it's never worked. What might be the problem?

JamesC

 

i forgot that our cars were setup that way, guess i am to use to working on late model cars.

anyway, about the lighting in the 85 roc, they mean the lights on the floor kick panels, and the hatch light (otherwise known as courtisy lights), so dont get those confused.

thanks
anthony

 

Would it not be possible to put the capacitor on the negative side then? It's capacitance should then serve to store some "negative voltage" (i know that's not a "proper term, but spare me)? When the ground is removed, the lights would then dim as the capacitor discharges.

just an idea...

 

i dont think that would work because the light bulb consumes all voltage that goes to it. also, the switch controls the ground, so when the door is closed, the ground is cut off. no ground = no light. there is no easy way to make the capacitor work short of using a times ground relay, in which case the capacitor would be usless.

thanks
anthony

 

Wouldnt a cap in parallel work?? Correct me if I am wrong here but the cap would charge when the light comes on (switch closed) and then discharge across the light when the switch opens?

 

yes that would work with constant ground, what your saying, put the cap just in front of the load,but the downfall is that the bulb may burn to hot when power is in constant supply. our cars have a constant power and the ground is what is cut off, so a cap will have nothing to discharge to, because the bulb requers a ground to burn. i would have to look at a wireing diagram of a newer caddilac to see if there is a way to do it with constant power (caddy always does everything differnt from the other cars).

thanks
anthony

 

I have no idea what you are talking about with putting the cap in front of the load?? I said put it in parallel with the light. When the switch is closed the cap charges, then when the switch is open the cap discharges across the light. And I have no idea what you mean about the light burning too hot. Just use a 16v cap so it wont blow when the alternator is spinning and the voltage wont be any higher than 16v then. Sounds like it will work to me...... and is very simple

 

Scooter... the cap won't be able to discharge across the light when the switch is open, becuase the switch doesn't open between the battery and the light, it opens between the light and the ground. The capacitor then will always be charging. Everything in these cars is switched like that.

 

i guess i should have read that better, but hey things happen when three things are being done at one time.

good thing i didnt let something like that slip at work or i would have never herd the end of that one

thanks

 

would it be that hard to just change the way the door light works all together?

 

One way it could be done is to use a 2 pole relay with a full time 12v input and the ground on the relay connected to the door pin switch. Then a chassis ground on the input of the relay and the “power off” pole on the relay to a bleed circuit. So when the door is opened it bypasses the power bleed circuit. But once the door is closed the relay goes to the other pole (power off pole) where it would have a circuit that slowly increased the resistance across the ground terminal until it got to infinity and the light would be off.

or with a litte playing around I am sure you could get this circuit to work: https://www.thirdgen.org/techbb2/sho...threadid=13581

Like switching it on with a relay. Don't really have time to mess with it now, have to get my car running first. Then i will see what i can do.

 

I know I have read that they actually make setups to plug in and make this work in older cars that werent equipped so that you dont have to rigg it up. Anyway, I dont know if they make a such thing, but if there is such a thing as a timed relay or you could put a capacitor in line with a relay you could have the relay open a bypass ground. Although thinking about that you would have to have another relay in line so that the light wouldnt be on all the time when the car was running. It would have to close the circut when the car was off and then the other one would only stay on a with a time limit until it reopened the bypass circut. Overall there is no way that that is anywhere near worth dicking with that much. I would just look into getting the premade setup that I know I have seen somwhere. I think it may have been mentioned on here before.

Ben

 

see if this would work

 

I dont quite understand your plan but I think it would work. I actually thought of something like that, but you wouldnt probably want that ground to continue back to the switch. The only thing that would be attatched to the switch is the ground for the relay. Then you would have to have power into and from the relay and up to the light. The actual ground for the light would just be on the chasis instead of to the switch now though. The reason I didnt mention something like this is because I dont know the willingness of someone to pull down the headliner to rewire the light. Actually though, thinking about it, you wouldnt have to if you could find where the power wire comes down from the light. You could just disconnect the ground from the factory switch and ground it to the chassis near by. You then would just have to attatch a wire from the switches to the ground on the relay and find and tap into the wire to power the light and attach the power out from the relay along with the capacitor there. Does this make any since?

Ben

 

sounds good, i would like to see someone do it.

 

91 black gta, that circuit will not work. The light will never light. In a dc circuit a capacitor is open.

Here is what you need to do:

Take a cap of the proper size (this could easily be calculated if you know the wattage of the lamp), attach it in parallel across the light bulb making sure your polarity is correct. This will charge when the light is turned on and fade the light off when the switch opens. The fact that the switch is on the negative instead of the positive is moot. It makes no difference to the light/cap system. You do not need a relay at all.

If you want the light to fade on as well you need to put a resistor in line with either the switched ground or the positive supply to limit the inrush current when the switch closes and the cap begins to charge. This will have some affect on the total brightness of the bulb, depending on how long you want it to fade on and what size your cap is.

Hope this clears things up. This is a really simple circuit, anyone who's taken physics 2 or circuits 1 should be able to do the calculations to determine the size of the cap and resistor.

 

Oops that was actually me that posted the previous replay, but someone else was logged in instead.

 

http://www.electronic-circuits-diagr...carsckt3.shtml

 

Slickroc55
Can you perhaps show me a diagram. That does make sense to me know.

 

Either way, it doesn't matter. You connect the ground of the cap to the ground wire of the light. Then the positive of the cap to the positive of the light.

This would be AFTER the switch and BEFORE the light. Once the power is cut, the cap does its job because the cap was not disconnected. It doesn't matter what gets disconnected as long as its before the cap. I've done this iwht LEDs a few times.

What happens is the cap acts like a battery with either the negative or postive disconnected. They are polarized, and stop charging when either side is disconnected.

And I wouldn't say "between the battery and the light", thats just not right in electrical terms. The ground is actually connected to the battery, so both the positive and ground are "from the battery". What would be right is that "the door switch opens or clsoes the ground side of the light, instead of the positive side"

 

Heres a little more info. You need to use an electrolytic cap. These are for DC voltage and hold a polarized charge. Both diagrams I attached will work.

Now comes the issue of what size of cap. I'm guessing it will need to be pretty big for a radio shack variety cap. The biggest they have is 4700uF and one of those doesn't run an LED for very long

LED = low power consumption
headliner bulb = high power consumption

Maybe a circuit that keeps the biulb connected to the battery for a defined time would be better.

EDIT: Mr. Dude's circuit was what I was thinking of

 

heres a better question.


where in the car does the ground going to the lights split off to goto each door? IE where does the two wires for the door switches come together??



i need to find that point so i can add my circuit (not the one i linked to, just a idea right now....)


if it works, i'll post it.. and if not... i wont post it.

 

I don't know that, but the only thing I would change in the linked circuit would be move the switch from the + side to the ground side. I wasn't sure if everybody caught that, I didn't until I looked at it a few times.

I'm much more of an electronics guy than a car guy LOL

 

another idea would be a circuit that fit into the dome light itself, and used a ground from the Ttop bar or the roof.... then the circuit could see when the light switch is open and it would run for a amount of time and dim out...


athough that would not work for me, since i have a vert. my "dome" light is built into my rearview mirror.

 

I don't think I want to tear mine apart, it looks like it is scrwed in fromt he top and you can't get to anything other than the bulb from inside the car. I'm having enough trouble fixing the gaping rust holes where the struts are supposed to be. In the near future I'm going to replace the headliner and cloth stuff, so maybe I'll check into it then