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Transistor overheated

  1. Jan 19, 2010 #1
    Dear Experts,

    I am using a NPN transistor part number C33840 (i think aka BC338-40).

    The collector is tied to Vcc @ 12V.
    The emitter connects directly to the capacitor of 1000uF.
    The base is supplied with a small current of about 0.9mA (1 LED) from a 1k resistor (in series with the LED) before it.

    There is switching going on with the transistor. Prolly 10 hertz.

    May i know how to prevent the transistor from overheating or the possible causes? I have 1 such transistor fried after running the circuit for a very short while.

    Last edited: Jan 19, 2010
  2. jcsd
  3. Jan 19, 2010 #2
    Hello Ramone,
    Could you please post a circuit diagram? If you can't do that, could you at least give a fuller description of your circuit.

    You need to explain it all the way round from one end of the 12V supply, through the LED and the transistor, to the other end of the 12V supply.

    Most importantly, are there any other resistors in the circuit apart from the one in series with the base? If not, this may explain the problem.
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