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12v Flourescent Ballasts — Parallax Forums

12v Flourescent Ballasts

william chanwilliam chan Posts: 1,326
edited 2009-07-08 02:31 in General Discussion
I want to design my own 12v DC fluorescent light ballast.

There are a lot of cheap 12v ballasts in the market, but most are unreliable, inefficient, electrically noisy and some overheats.

Can I use the SX to create a sine wave to be transformed to about 600v so it can strike a fluorescent light tube without any heating delays?

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Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-07 16:09
    Maybe. What have you investigated on your own so far? Do you know what frequency you want to use?

    -Phil
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-07 18:15
    I'm very interested in this too - a high frequency, like are used in TV & Film stage lighting equipment, would be wonderful. I'm not sure what they run at ... I'll edit-in info here, but I suspect they're > 1kHz to avoid interference with the video's scans.

    - H

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  • william chanwilliam chan Posts: 1,326
    edited 2009-07-08 00:24
    I am thinking of running the SX at 50Mhz to produce a perfect sine wave (by PWM) at the mosfet output.

    Can I use 6v-0-6v : 240v 1A center tapped transformer to produce about 480v output.

    Will it be sufficient voltage to strike a regular 4 foot 36 watt tube?

    What is the best way to wire up the mosfets for best efficiency?

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    www.fd.com.my
    www.mercedes.com.my
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-07-08 00:40
    William, there really isn't any reason to run a sinewave at a 50MHz sample rate... 1MHz would be MORE than sufficient for this application. If your objective is just LIGHTING the tube, then try a 1KHz square wave through the transformer. Also, use a MOSFET driver chip, like the UCC27322 to drive some MOSFETs in parallel(with resistors at each base ~4.3ohms).
  • CounterRotatingPropsCounterRotatingProps Posts: 1,132
    edited 2009-07-08 00:44
    Aren't there cheap chips designed to do just this and be stable?

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  • william chanwilliam chan Posts: 1,326
    edited 2009-07-08 02:31
    Phil,

    What I meant was running the SX at 50Mhz to produce a 1Khz sine wave.
    Would a square wave be more efficient than a sine wave?
    Will it cause standing wave patterns in the tube?
    Could you give an example of how the SX and mosfets should be wired to the transformer?

    Thanks.


    "Aren't there cheap chips designed to do just this and be stable?"
    There are, but the SX is readily available in my drawers and I can customize it to do other things like IR remote receiving.

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    www.fd.com.my
    www.mercedes.com.my
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