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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:
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    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: http://www.mp3car.com/vbulletin/show...&postcount=247 As well as Zip-Lock, link: http://www.mp3car.com/vbulletin/show...&postcount=248

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

    Comment


    • #3
      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
      Signature: [==||========] 20% complete

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      • #4
        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
        Signature: [==||========] 20% complete

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        • #5
          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).

          Comment


          • #6
            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.

            Comment


            • #7
              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
              95 Mustang GT Convertible
              87 Mustang GT Convertible
              My Project | Let's Go Mets! | SCT Tuners

              Project Status [===#===] [Bezel and dash creation]

              Comment


              • #8
                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.
                Carputer status: [-*---------]
                Im thinking laptop...

                Comment


                • #9
                  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.

                  Comment


                  • #10
                    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.

                    Comment


                    • #11
                      Originally posted by LiquidKernel
                      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.
                      I had an idea last night that I thought would be cool - it doesn't have anything to do with the dome light, but if it is able (to be determined) to dim the inverter for a ccfl, then why not the inverter for an lcd? I am using a phidgets controller and light sensor to adjust the brightness of the screen according to ambient light. I have written the program for the sensor and I can tell how bright it is, but I haven't thought of a way to tell the inverter to lower the voltage to the backlight. If it were possible to allow serial port control with your unit, and it is possible to control the ccfls, couldn't you install one of these units in between the LCD controller and inverter?

                      If you don't want to get into this sort of area for your dimmer right now, you can tell me to shut up. I just thought about it last night...Either that or I could wait for the backlight upgrade guys to finish their project and see if I could fit their backlight dimming solution. If it's getting too far away from your original intent and would rather not get into it, I understand.

                      Just a thought

                      - Jeff
                      95 Mustang GT Convertible
                      87 Mustang GT Convertible
                      My Project | Let's Go Mets! | SCT Tuners

                      Project Status [===#===] [Bezel and dash creation]

                      Comment


                      • #12
                        oooo i never thought about adapting this to use with the backlight upgrade.

                        The inverters usually have the following options:

                        external PWM input into a a control pin that causes dimming or CCFL heating for low temp running

                        internal PWM with voltage input pin from 0-5V that controls the PWM dimming

                        I have been having torube finding a dimming inverter for a different type of tube to CCFL as tey are so new but i think i might have one now. I was wondering about just applying a PWM controlled voltage into the inverter to bodge it though.

                        jzgt, i have a thread on the control circuit for the backlight dimming i need to update so i will keep you posted as i thinkw e can probably help eachother out. (the info above shoudl help with your integration to the inverter).

                        If you use a new style xenarc screent he inverter is separate but i don't know which pin is the control pin yet. Normally you have 4 wires: ground, +12v (or 5V), enable (on/off) and control pin (PWM or 0-5V voltage).

                        PWM dimming is also the best way to go with LEDs.

                        Comment


                        • #13
                          Originally posted by LiquidKernel
                          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.

                          we are planning on something liek that with the CCFLs - ie autodimming but with a manual level adjustment to define the level. We are hoping to have it push button based using a PIC to store the settings as it looks a bit more proffesional than a knob or scroll as we suspect it will be on show and mounted next to the screen.

                          Comment


                          • #14
                            Originally posted by Scouse Monkey
                            oooo i never thought about adapting this to use with the backlight upgrade.

                            The inverters usually have the following options:

                            external PWM input into a a control pin that causes dimming or CCFL heating for low temp running

                            internal PWM with voltage input pin from 0-5V that controls the PWM dimming

                            I have been having torube finding a dimming inverter for a different type of tube to CCFL as tey are so new but i think i might have one now. I was wondering about just applying a PWM controlled voltage into the inverter to bodge it though.

                            jzgt, i have a thread on the control circuit for the backlight dimming i need to update so i will keep you posted as i thinkw e can probably help eachother out. (the info above shoudl help with your integration to the inverter).

                            If you use a new style xenarc screent he inverter is separate but i don't know which pin is the control pin yet. Normally you have 4 wires: ground, +12v (or 5V), enable (on/off) and control pin (PWM or 0-5V voltage).

                            PWM dimming is also the best way to go with LEDs.
                            Thanks very much for the info. I have been watching the work you guys are doing and it looks great! I am currently using an Allbrite, but after getting into the fab work required to put it in the dash and the great work you guys are doing with to increase brightness levels, I think it may be easier to swap in a spare dash (I've chopped mine up beyond all recognition ) and fab a bezel for the much smaller xenarc...I haven't totally given up on the large screen - I'll see how I like it once I've finished the fiberglass work.

                            But yeah, I'd love to help out! I have another screen (LQ10D367), inverter and controller setup that I'd be willing to blow up in the name of science.

                            - Jeff
                            95 Mustang GT Convertible
                            87 Mustang GT Convertible
                            My Project | Let's Go Mets! | SCT Tuners

                            Project Status [===#===] [Bezel and dash creation]

                            Comment


                            • #15
                              Originally posted by Scouse Monkey
                              oooo i never thought about adapting this to use with the backlight upgrade.

                              The inverters usually have the following options:

                              external PWM input into a a control pin that causes dimming or CCFL heating for low temp running

                              internal PWM with voltage input pin from 0-5V that controls the PWM dimming

                              I have been having torube finding a dimming inverter for a different type of tube to CCFL as tey are so new but i think i might have one now. I was wondering about just applying a PWM controlled voltage into the inverter to bodge it though.

                              jzgt, i have a thread on the control circuit for the backlight dimming i need to update so i will keep you posted as i thinkw e can probably help eachother out. (the info above shoudl help with your integration to the inverter).

                              If you use a new style xenarc screent he inverter is separate but i don't know which pin is the control pin yet. Normally you have 4 wires: ground, +12v (or 5V), enable (on/off) and control pin (PWM or 0-5V voltage).

                              PWM dimming is also the best way to go with LEDs.
                              That's quite interesting. I had no idea inverters had the option of using external PWM to control brightness. Is this a common thing? I'm wondeirng which do this.

                              Comment

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