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need help with quick and dirty triac triggering please.

Discussion in 'Electronic Basics' started by Kevin, Oct 16, 2004.

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  1. Kevin

    Kevin Guest

    Hi, wondering if some kind sole can help me out.

    problem is timer module on washing machine is none working with regard to
    motor drive, I think the tda1085c chip is dead, machine is about 5 years old
    and new timer is apparently about a 100GBP so ordered new machine, trouble
    is one we want will take 10 days min so I figure I ought to be able to
    manually control motor speed and get some use in the mean time.

    It's quite some time since I did any meddling with electronics, I still have
    quite a lot of caps and resistors though I seem to have forgotten most of
    how to use them!

    Anyway what I'm attempting is to put an RxC network into the old triac gate
    feed instead of from the triac controller chip. I've managed to find a 0.1uf
    capacitor of a type I beleive to be suitable for 250 vac,( I'm in uk so 250
    vac mains), also I think I can get a 120vac feed from the large dropper
    resistor that's on the board, I've got a 50k duel pot and lots of other
    fixed resistors of 0.25 maybe some 0.5 watt.

    The triac is marked btb15-600bce, I assume that means it's a 15 amp 600volt
    but I havn't been able to get a datasheet and don't know what the trigger
    values are, I also don't have any diacs so would like to drive it direct
    from my RxC network, it's only a temporary measure for a few uses.

    If someone can tell me whether it's feasable without the diac and perhaps
    the resistance values to use with the 0.1uf cap, I'll be isolating the pot
    body inside the machine out of the way with just the plastic shaft
    pertruding. I also expect to have to adjust the wash speed for each
    different load but it will be easier than trips to the launderette and
    cheaper, so if anyone can help it would be great.

    thanks in advance
  2. CFoley1064

    CFoley1064 Guest

    Subject: need help with quick and dirty triac triggering please.
    Hi, Kevin. It's a little more complicated than you envision. It isn't worth
    the hassle, especially if you're not sure what you're doing. And you are
    talking about potentially lethal voltage in the presence of a tub of sudsy
    water and a big grounded chassis.

    Try the laundromat. You may spend a few more pounds, but you don't want the
    excitement you may be missing as a result.

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