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Thread: lilliput backlight pinout for manual dimming

  1. #21
    FLAC coucouillu's Avatar
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    Quote Originally Posted by bbalazs View Post
    I cut the wire on the panel that went to the CCFL drive (two transistors via a coil) and put a small smd PCB made by me, it contains a small FET and a PIC with a transistor (because it is a P-FET) That 10F206 PIC just works as a PWM, concerning the two input pins, making four possible PWM (100%, 50%, 25%,10%).
    Below 10% it is tending to flash and being unstable.
    Coul you post details of your project?

    Thank you.

  2. #22
    Variable Bitrate
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    Skuller: In that case you can use a simple potentiometer with high performance serial with the pink/white wires. (I mean approx. 20 Ohms,10W) like the dashboard-dimmer of certain cars.

    Coucouillu: What project? It is a very ugly smd panel (two very small panel on the top of each other). It just contains an irlms6802 small 5A fet, a driver transistor-pair (for 5V-12V drive, and a pic10f206 (very small and cheap) for the pwm. The PWM solution is from software. I can attach the program, if you want.
    gp0 and gp1 are inputs, and have a slight pullup internally, you can pull them to the ground with a switch.

    The most difficult method to find the location of 12V input on the backlight panel, because it varies with the manufacturer, but usually there is a coil BEFORE reaching the two fets or transistors, and one ending of that coil is the hot spot for us.


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  3. #23
    Variable Bitrate
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    Coucouillu: It was a hard work to get the picture out of the tango2...
    I also attach the 'sophisticated' program.
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  4. #24
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    Sorry to dredge up an old thread. Has anyone here been able to get manual backlight dimming to work on the new lilliput LED panels?

    I have a 629GL. It is similar to Skuller's, except the LED backlight is connected to the board directly behind the panel with a ribbon cable. There is only one brightness control in the menu, and the backlight stays the same whether it is set to 0% or 100%.

    The only way I can see getting this done, is by wiring up some sort of PWM in series with the backlight (like bbalazs, but with LED). I can't find any info on the net, but a lot of places selling this screen list "backlight control (dimming) available" as a feature. Even the lilliput website says there are 4 different backlight levels. This tells me that there might be an easier way.

    Skuller, if you are still watching this thread, where did you read about the backlight control pin (0 -3.3V)?

  5. #25
    Variable Bitrate
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    Another thread bump dredge, but searching ended up here.

    Does anyone have an idea of how to create a circuit easily that would take the input of your headlights and cut brightness by say 50% directly?

    It seems that if a person hooked a relay up to the headlight lead for the stereo it would be possible to do something like this. It seems that having the wires going to the backlight be diverted into the relay, and one circuit for no headlights and full power, other circuit for headlights with a resistor inline, then combining into an adjustable potentiometer (as mentioned 20 Ohms,10W) might be a might way to do it.

    I can adjust my brightness manually, but it would be nice if it just did it automatically, or maybe a better idea is to put the adjustable pot in series with the headlight on switch and leave it at that. Then max brightness in the day and adjustable brightness at night that can be set at a given value and adjusted up or down if desired.

  6. #26
    Maximum Bitrate Mickz's Avatar
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    This seems like a crude way to control backlighting. I posted some information and a circuit of a LED backlight controller that may be of interest.

    2004-honda-accord-dual-climate-control-interface-and-car-pc-touch-screen-control

    And in this thread lcd-display/152493-controlling-back-lights-directly

    I understand that you have a different LCD, however the controller and design principle should be similar. These are industry standard devices.
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  7. #27
    Variable Bitrate
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    Wow that is awesome. Thanks I will read the linked threads and see if I can figure a way to connect it to cluster dimmer switch. That would definitely be far superior. Funny I wanted to move my PC out of under the seat to the inside of the dash behind the screen, but after reading partially through your thread that no longer seems like such a fantastic idea.

  8. #28
    Maximum Bitrate Mickz's Avatar
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    Thanks, BTW nice work on what you've accomplished so far. There have been a lot of changes to the look and quality of my FE but I haven't updated the thread for a while.

    Mounting behind the dash is still feasible in some installations but once you start there is always a new idea, something to add or update, in the end I wanted quick access to everything and minimal interference to GPS receivers.

    Always happy to try an help if you need any info or ideas with interfacing to the existing cluster.
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  9. #29
    Raw Wave
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    Quote Originally Posted by sxott View Post
    Does anyone have an idea of how to create a circuit easily that would take the input of your headlights and cut brightness by say 50% directly?
    Like DRLs?
    Often that is done with a relay (DPDT?) that connects the bulbs in series - ie, breaks their commonly joined ground from GND and swaps one filament's +12V connection to GND.
    But that's only for un-ballasted stuff like tungstens and halogens - not LEDs not HIDs.

    Otherwise a normal dimmer and change its MOSFET to a 50A - 100A rating. That assumes it's a grounding MOSFET dimmer.

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