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Thread: IGBT vs Triac

  1. #11
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    Dec 2011
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    Default Re: IGBT vs Triac

    Actually the 5W bulb is not enough .
    A string of 100 incans 50/ 1/2 wave with 50 turned off works .
    Unfortunately I cannot reduce the string further as if I remove 1 all 50 go out .

    I need to find a way or string that is full wave i guess to find the exact amount of drop required.
    I tried a parallel load of 100 leds which has no effect at all .

  2. #12
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    Default Re: IGBT vs Triac

    It is amazing how nice the dimming is with the hw .lib and a parallel load of incans.

    This is dimming from 20 -> 40 out of 0 - 175 scale.


  3. #13
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    Default Re: IGBT vs Triac

    A little history. IGBT dimming was introduced for commercial use by Entertainment Technology many years ago (early 1990s) for theatrical dimming. The devices had been growing in power handling capacity and dropping in cost due to use in the motor drive industry. IGBT technology has since been adopted by many other dimmer manufacturers since you can do both forward and reverse phase control.

    You can also control the rate of rise (or fall) time of each half cycle of the AC, reducing filament noise in large incandescent lamps. So ET was able to offer 800 microsecond dimmers when others had to use huge chokes, wasting power, to achieve that performance with traditional SCR/Triac dimming.

    Another benefit of IGBT dimming is computing the turn off time on the falling edge of the sine wave to keep the RMS voltage constant even with line voltage fluctuations. Of course all of that required a microprocessor and voltage and current sensors so those dimmers tended to be more expensive and were more typically used for higher performance applications at first. They are also essentially short-circuit proof since the microprocessor can sense a current inrush quickly enough to kill the trigger signal on the IGBT.

    Of course today you can get wallbox dimmers for home use that use IGBTs from Lutron and other companies since embedding a microprocessor in a small device is no longer a costly proposition. In any case, it all uses zero-crossing sensing to trigger the timing.

  4. #14
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    Default Re: IGBT vs Triac

    Angus,

    How is this working out? Or are you busy vacationing or fishing?
    Phil

  5. #15
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    Default Re: IGBT vs Triac

    Sorry, I have been in 12 directions from Thursday , with renovations at home , building product moving devices for my parents shop + working eves at my own business .
    I haven't had time to focus with the scary AC .

    Hopefully I can get to building this circuit this week though it isn't high on the honey do list .

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