Help with a triac, afraid of burning it :)

Discussion in 'General Electronics Chat' started by Artikbot, Nov 7, 2010.

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  1. Artikbot

    Thread Starter Member

    Nov 7, 2010
    Hi there,

    I'm Artikbot, newcomer in AAC. I've been working on electronics for a little time now, but have managed to build some successful circuits involving some basic ICs.

    Well, I have a question. After browsing a lot through AAC, looking at the Triac section, and all around Google, I still haven't managed to get to work mine.

    I'm using a BTA40-700B 700V 40Amp triac (in a large RD-91 package xD) for purposes of HV switching (capacitors discharging in a burst :p).

    The thing is:

    I've managed to get to work my SCRs, since they're nothing more than a gated diode, but this triac is driving me crazy! They're meant for AC, but can be used for DC aswell they say. I've read that I need to interconnect lead 2 to gate with the adequate resistor, and current must come from gate 2 side in order to make the triac successfully trigger.

    So there we go, I solder some leads to the triac, wire an adequate resistor (letting a 25mA current flow through T2 to gate), hook a LED onto T2, hook power to T1, the another terminal onto negative part of my supply, hook a switch between G/T2 terminals, hit the switch and...

    Nothing happens! Erm, LOL? What's wrong? I did exactly what AAC samples said... The triac is brand new, and I've tested it according to AAC's guides and everything is correct.

    I'm applying 7.4V for testing purposes. Real load will be somewhere between 310 and 330V. And not a few mAmps, hundreds of Amps for an about 10ms time xD

    Any help will be widely appreciated :)
  2. mik3

    Senior Member

    Feb 4, 2008
    Post the circuit.
  3. beenthere

    Retired Moderator

    Apr 20, 2004
    I'm sorry we did not catch this sooner. High voltage/high current discharges are among the topics we do not discuss here. The potential for harm is just too great.
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