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Thread: Opinions and suggestions on my dome light dimmer project

  1. #1
    Maximum Bitrate LiquidKernel's Avatar
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    Opinions and suggestions on my dome light dimmer project

    Instead of re-inventing the wheel, I will just post what I had in my previous thread. I have already received quite a few great suggestions from various members and am taking them into consideration. To stay within the rules, I must ask that you do not ask me to sell any of these. Once it is fully developed I will (hopefully) get permission from the admins and then update this thread.

    Original Post:
    -------------------------------------------------------------------------

    Since my buddy and I started working on this project, we've ran into a bunch of issues with various cars. Most of the time it was a problem caused with the car not having "digital friendly" grounds that never really went to 0V, so it made our design problematic. An optoisolator fixed pretty much all trigger issues. But it made the PCB bigger =[

    The design is fairly simple. We put it "inline" with the line that powers the dome light when the door is open. We used the input as a trigger and the wire going to the bulb would be controlled by the MOSFET (which is controlled by the MCU). There are pretty much no discrete parts in our design, so we this allowed us to keep it small and adjust the timing to the split-second.

    We also made two variations. Low-side and high-side control. Low-side works on cars where the bulbs turn on when a ground is fed. The high-side works on cars where the bulbs turn on when 12Vs if fed to them. Most cars have the low-side variant.

    Tested on: Volvo 850 (pre '96, '96+ fade already), previous generation Honda Accords, Civics and Acura Integras.

    We received our pre-made PCBs just recently (even though my car still has one of the development protoboard ones) and they are smaller than ever...

    Here's what it accomplished:
    Video 1
    Video 2
    Video 3

    Doesn't seem like much, but it's a nice little feature

    And here's our first REAL PCB... (the pic doesn't have the heatsink shown, I took that off for the photo). I must say, it feels nice having your own PCB...


    So far the following ideas have been suggested:
    * Using a little trim pot to adjust dimming/fading time
    * Using one of the MCU I/O pins to allow serial-port control <-- HIGHLY interested in doing this one. It will allow your carputer to tell the lights what to do!

    Any more suggestions are greatly appreciated and welcome!

    Boris: This thread has been approved by frodo. Link: Dome Light Fade-in and Fade-Out Successful! As well as Zip-Lock, link: Dome Light Fade-in and Fade-Out Successful!

  2. #2
    FLAC
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    LiquidKernel you have my permission to develop this project. Good luck with it.

  3. #3
    Nic
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    are you able to make the light stay on for about 10 seconds after you leave the car, i guess you could add some sort of ign/acc wire input, if that wire is high then fade out immediatly, if it isnt high then wait 10 seconds to fade out
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    Nic
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    actually screw that i think its a stupid idea, but i do have an idea for a simmilar project how about a small PCB circuit that turns the lights on/off when its dark, and then leaves them on for 30 odd seconds as you leave the car

    edit: i mean headlights
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    Maximum Bitrate LiquidKernel's Avatar
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    Quote Originally Posted by Nic
    are you able to make the light stay on for about 10 seconds after you leave the car, i guess you could add some sort of ign/acc wire input, if that wire is high then fade out immediatly, if it isnt high then wait 10 seconds to fade out
    That is indeed possible to do actually. However the reason I did not do that initially is because this was done with my car in mind and I already had a time-delay for the dome light. Just no fade/dim feature.

    If the key is not in RUN it can have a delay. But then you'd want to have another line setup so that when it's not in ACC to have it fade out right away (ie, when locking the car).

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    Maximum Bitrate LiquidKernel's Avatar
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    Quote Originally Posted by Nic
    actually screw that i think its a stupid idea, but i do have an idea for a simmilar project how about a small PCB circuit that turns the lights on/off when its dark, and then leaves them on for 30 odd seconds as you leave the car

    edit: i mean headlights
    I believe there are quite a few of these already around. The leaving lights on as you leave the car is known as "Follow Me Home" in some cars. I thought about making this but since it was already done, I scrapped the idea.

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    Maximum Bitrate jzgt's Avatar
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    I really like the idea with the serial port and control - how hard would that be to implement? The wheels are spinning in my head for my front end software...The more I can do from the touchscreen, the better

    I am going to be removing the current bulbs and sockets from the totally inadequate interior lighting scheme in my car and replacing them with some 4 or 6" ccfts and inverters. I'm assuming that your board would work with that, right? Have you tried it? It should work as I would assume anything that is powered by the circuit in which your piece was installed would slowly fade up to full power and slowly fade out to off, right?

    - Jeff

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    Maximum Bitrate shizzle's Avatar
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    I just want to voice my support for the project, I think the dimming dome light is a great feature and Im glad my car has it already. Even if just doing it for yourself it's worth it, but obviously others are interested.
    One suggestion that I have would be to implement a dimmer switch that could be used manually at any time the light is on. I would love to have such a feature in my car...it would be especially usefull while driving on the interstate at night. As it is, I find myself using the small lights on the vanity mirrors while driving at night because they arent as bright. Being able to turn the dome light on to a dimmer setting would be awesome, and seems like it wouldnt be much more work.
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    Maximum Bitrate LiquidKernel's Avatar
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    Quote Originally Posted by jzgt
    I really like the idea with the serial port and control - how hard would that be to implement? The wheels are spinning in my head for my front end software...The more I can do from the touchscreen, the better

    I am going to be removing the current bulbs and sockets from the totally inadequate interior lighting scheme in my car and replacing them with some 4 or 6" ccfts and inverters. I'm assuming that your board would work with that, right? Have you tried it? It should work as I would assume anything that is powered by the circuit in which your piece was installed would slowly fade up to full power and slowly fade out to off, right?

    - Jeff
    From what I know about AVR programming, it is not hard. It is definitely something I want to play with... would be nice to have total control of your dome lights from the front end.

    To tell you the truth, I am not sure that CCFLs can be controlled with PWM (though not certain on this). It maybe possible but I am not entirely sure. I will research this some. The result of the PWM is that the voltage raises (fades in) and drops (dims out). So if the CCFL inverter can take that voltage change and change the intensity of the CCFLs, then it should work.

    There is a limit of 100W on the MOSFET of the module however. The heatsink I have on mine is only good for some 50Ws at most. So depending on how much the CCFL inverter drains you might need a bigger heatsink.

  10. #10
    Maximum Bitrate LiquidKernel's Avatar
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    Quote Originally Posted by shizzle
    I just want to voice my support for the project, I think the dimming dome light is a great feature and Im glad my car has it already. Even if just doing it for yourself it's worth it, but obviously others are interested.
    One suggestion that I have would be to implement a dimmer switch that could be used manually at any time the light is on. I would love to have such a feature in my car...it would be especially usefull while driving on the interstate at night. As it is, I find myself using the small lights on the vanity mirrors while driving at night because they arent as bright. Being able to turn the dome light on to a dimmer setting would be awesome, and seems like it wouldnt be much more work.
    I'm glad you appreciate the project

    I am thinking that for limiting the brightness of your dome/map lights you can just setup a simple potentiometer or any other rheostat and put it in series to the bulbs in the dome/map light.

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