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

    Retired Moderator

    Jan 28, 2005
    9,030
    218
    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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