Sound from amplifier, without a speaker?

Discussion in 'General Electronics Chat' started by paultwang, Apr 6, 2006.

  1. paultwang

    Thread Starter Well-Known Member

    Mar 8, 2006
    80
    0
    I was testing my discrete BJT audio amplifier yesterday. It does not have a speaker yet! The speaker is subsituted by a dummy resistor load. I heard sound coming from somewhere on the amplifier breadboard. The sound is very soft, but is at the correct frequencies as the function generator. How is it possible?

    No capacitor, a few resistors, 12 BJTs, no coil or inductor.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    It is possible that your dummy resistor may be of the wirewound type. Wire-wound resistors can produce a weak audible output when driven with a high current.

    hgmjr
     
  3. Creek

    New Member

    Apr 11, 2006
    2
    0
    You could also be vibrating off a cracked resistor.
     
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