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increasing current capability of a lamp dimmer

Discussion in 'Electronic Basics' started by m b, Oct 19, 2012.

  1. m b

    m b Guest

    I would like to use a lamp dimmer to control an infrared heater.

    The heater is 1500 watts, and the biggest (cheap) dimmers I have found
    are 600 watts.

    I managed to get a deal on some 40 amp triacs on e-bay ...

    I believe the following should work (using the home depot dimmer as a
    trigger for the high current triac) can anyone verify it ?



    --------------|
    | |
    .-. |
    | | |
    | | heater |
    '-' |
    | |
    | |
    | |
    | |
    _|_ |
    V_A triac |
    |----/ | |
    | | |
    | | |
    .----------. | | |
    | | | | |
    | home |---- | -----------
    | depot | |
    | dimmer | |
    | | |
    | |----------|------------------------
    | | -
    | |
    '----------'







    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
     
  2. Jamie

    Jamie Guest

    If you have a triac type dimmer from Home-Depot, you could unsolder
    the wimpy one and replace it with the large one you have. And of course,
    heat sink it.

    Jamie
     
  3. Tom Biasi

    Tom Biasi Guest

    It depends on how the dimmer is designed. A lot of times the load is in
    series with all the other circuitry and you won't have a convenient way
    to get the trigger pulse.
    As was suggested, if the circuit board looks like it can handle the
    extra current maybe you can swap triacs and add heat sinking. Then hope
    the diac and your triac are compatible.

    Tom
     
  4. m b

    m b Guest

    I made a mistake on my schematic the first time through, the dimmer
    should connect the gate to MT2 (not MT1) the corrected schematic is
    attached below

    Built it as shown, and it worked perfectly, it dimmed from very low
    power proportionally through to full power.
    I had it jury rigged, with just masking take covering the connections,
    and no heatsink on the triac, which was ok for brief testing, but
    would have overheated eventually.

    The heater "sang" quite a bit since I used no RFI suppression caps or
    coils ... may change that, may not bother ...

    I guess I'll build it into a box for permanent use.

    Corrected schematic shown here

    --------------|
    | |
    .-. |
    | | |
    | | heater |
    '-' |
    .------------. | |
    | | | |
    | |---------| |
    | Home | | |
    | Depot | _|_ |
    | Dimmer | V_A triac |
    | |-------/ | |
    | | | |
    | | | |
    '------------' | |
    | |
    | -----------
    |
    |
    |
    ------------------------


    or alternately
    .------------.
    | |
    | home |
    | depot |
    | dimmer |
    '------------'
    OUTLET | | GATE
    to plug | ---------o
    load into | / 120 Vac
    .--------. | / Plug
    | | | |<| .---.
    | |--------------o--------|\|------o----------| |
    | (||) | MT2 |>| MT1 |
    |---
    | | | |
    | (||) | TRIAC |
    |---
    | |-------------------------------------------| |
    | | '---'
    '--------'


    created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)
     
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