Theater Dimming? - Page 3 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-10-2004, 09:24 PM   #21
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Quote:
Originally Posted by enmityst
Quote:
Originally Posted by Damemorder
You could add a bank of capacitors to your Interior lighting power lead, It would take a second longer for them to turn on, But they would dim off.
How much current do the interior lights draw all together? You might need a serious cap bank to store enough energy to make them dim noticeably slow.

-b
That'* on the list of things to test...
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Old 05-11-2004, 01:40 AM   #22
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Quote:
Originally Posted by Damemorder
You could add a bank of capacitors to your Interior lighting power lead, It would take a second longer for them to turn on, But they would dim off.
Cool feature! You could get around the time it takes for them to turn on by wiring the caps in parallel to the existing circuit and use a couple of diodes.. That way the stock circuit would control the "on" functions and the new curcuit would supply power once the stock circuit shuts off.

BTW, it seesm to me I might have seen something aftermarket (if not the schematics) to do exactly this somewhere online. No idea where I ran into it, though.
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Old 05-13-2004, 03:42 PM   #23
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hrmm... The SAFEST** way to do this is through a circuit using a timer and PWM (Pulse Width Modulation).

Instead of resisting (which turns the extra power to heat) to dim the lights, it turns the lights on and off so fast that the light appears dimmer. The slower it flashes the dimmer the light appears. And it does not waste energy on heat which could be important with the amount of power the lights draw.

This is only for the electronically inclined, but it is not a hard circuit to build so if you found someone that had spare time and knows electronics they could whip one up for you.

This summer i am planning to do this to my car as well...

*BE CAREFUL WITH CAPACITORS... you would need alot of them and touching one that is charged and big enough for the car could be FATAL... so PLEASE use CAUTION
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Old 05-13-2004, 04:25 PM   #24
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Quote:
Originally Posted by bmsgaffer86
hrmm... The SAFEST** way to do this is through a circuit using a timer and PWM (Pulse Width Modulation).
I thought about that as well, but you run into issues with dimming to full off via PWM -- eventually you're going to reach a pulse width that will be present itself to the eye as an annoying blink unless you use a high enough frequency, and high frequencies demand a load driver that'* capable of quick switching. Solid-state relays are probably out (most of the ones I've worked with aren't capable of turning on and off reliably hundreds or thousands of times per second), and they're expensive anyway, so you're most likely stuck with power FETs. Depending on how much power the interior lights draw, that might get expensive too.

It also might be difficult to get a 555 timer to automagically start dimming itself; most of the PWM circuits I've constructed used a pot to manually vary the pulse width. I'll look at it and see if there'* an easy way of doing it (unless you've got the answer already, in which case I'll shut the hell up ).

-b
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Old 05-13-2004, 05:31 PM   #25
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Lol i do not have a definate answer yet thanks for the input i wsa hoping someother electronic guru would pop in here because im not very advanced yet... but i see that makes sense about the low dimming... I think FETs are the answer in a nice box cause they'll make some nice high frequency noise like speed controllers proly right?... I do not think they draw more than 10A total so it wouldnt be terribly expensive but your right it wont be cheap either...

Im just kinda begining my delve into PWM...

And as far as auto diming i do not have an idea yet... i am along your same lines of manual pot dimming... but i mean really, it cant be THAT hard can it
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Old 05-14-2004, 03:59 AM   #26
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Hi see if this circuit will work?

http://www.csgnetwork.com/dimmerdelayproj.html
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Old 05-14-2004, 11:06 AM   #27
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I dont know if it will work but it sounds good? I found that and some more last night that i will post when i get home and find them again...
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Old 05-14-2004, 02:31 PM   #28
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Hi see if this circuit will work? http://www.csgnetwork.com/dimmerdelayproj.html
Actually, that looks pretty good. He'* right though, that load driving transistor is going to be creating a lot of heat while it'* dimming -- you'd definitely need a pretty beefy transistor and a nice heatsink.

But that circuit is beautiful in its simplicity. Good find

-b
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Old 05-14-2004, 06:11 PM   #29
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THank you lord for simplicity... its good to hear that it will work so now to get to that..

I can save my PWM circuit for my over 1 million color changing lights (building myself with primary color LED'* )
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Old 05-14-2004, 07:00 PM   #30
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Also remember that the 87-91 Bonnys have 11 interior lights and the 92-99 have 10, so the circuit will have to be designed to run 10 bulbs instead of 1 without dimming too fast.
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