Electroluminescent LCD backlight


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  1. #1
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    Default Re: Electroluminescent LCD backlight

    Hi Robert
    Just wondering whether you managed to get any headway with this one? I am trying to do exactly the circuit. I have been using a TS555 for the high frequency side and a NE555 for the lower frequency side. It is for a battery powered driver for EL wire so the voltage will vary between 3.9V and 4.8V. Did you find out how the inductance relates to the outputted Voltage?
    Cheers

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    Default Re: Electroluminescent LCD backlight

    Hi,

    You're lucky I read this, I've been away from the forum since I did this test.

    Yes and no, I got the backlight working by playing with the timers. It wasn't lighting up as bright as I hoped, nor was the voltage going as high as necessary. But it did light up, so the circuit is good in principle.

    I'll be getting back into this once I finish building a new batcave; hopefully by this summer.
    Last edited by Demon; - 5th May 2011 at 00:11.

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    Default Re: Electroluminescent LCD backlight

    That sounds good. I tried it again with a scope and couldn't get it working still. I think that I have bought inductors that are over- rated and I think this is the problem. I'm gonna order a range of 100uH ones with different current ratings and see how they work out. I also think maybe the 680pF capacitor is a little on the small side. Anyway, good luck on your bat cave

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    Default Re: Electroluminescent LCD backlight

    What is the rated current of your load?

    The inductors presented in this thread are just RF chokes and not intented for SMPS circuit use.

    If the inductor is saturated you may just burn the mosfet or the inductor itself.

    ON time, Vcc, MOSFET On resistance, Inductance and Inductor resistor are the factors to consider for the current through the inductor.

    Simple circuit but lots of math behind it.

    An oscilloscope is a must for the checks.

    Also, if you change places between MOSFET and Inductor and reverse polarity of the Diode, you can drop the second MOSFET. Just the polarity of Vout would be inverted.

    Ioannis
    Last edited by Ioannis; - 5th April 2011 at 08:15.

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    Default Re: Electroluminescent LCD backlight

    This was my first foray into this sort of circuitry. I was just looking for something to light up these LCDs and that was the only circuit I could find.

    If you can draw a better schematic to do this, I'd really appreciate it. Giving details on the parts needed would also be a huge help.

    In other words, assume you are talking to a 10 year old.

  6. #6
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    Default Re: Electroluminescent LCD backlight

    in other words, assume you are talking to a 10year old.
    *chuckle* At least you got some experience lately
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

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    Default Re: Electroluminescent LCD backlight

    Quote Originally Posted by mister_e View Post
    *chuckle* At least you got some experience lately
    You're only a 30 minute drive from here and don't forget I can run faster than you, even with my walker. :P lol

  8. #8
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    Default Re: Electroluminescent LCD backlight

    Quote Originally Posted by Ioannis View Post
    What is the rated current of your load?
    ...
    Googling for PC-016ATE, I made my way here via Wombat:
    http://www.serialwombat.com/parts/LCD-107.pdf

    mArms=2.9

    Also got more information on what we should aim for:

    Vrms=100
    fEL=400Hz
    Last edited by Demon; - 5th May 2011 at 01:19.

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    Default Re: Electroluminescent LCD backlight

    This circuit is interesting:
    http://www.simplecircuitdiagram.com/...mple-inverter/



    I just wouldn't know what to try as transformer to go from 5vdc to 100vac, nor how to control frequency at 400Hz.

    I don't have many transformers on hand to fry.

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    Post Re: Electroluminescent LCD backlight

    Try this and let me know how it works out.
    Name:  trans.jpg
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