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ultrasonic speaker simple amplifier

Discussion in 'Electronic Design' started by Infundibulum, May 30, 2007.

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  1. Infundibulum

    Infundibulum Guest


    I am using a simple 555 timer to create a 20khz + square wave feeding into
    an 8 ohm super tweeter rated up to 40Khz. I'd like to raise the power
    output on the speaker above what I get from the 555 timer pin 3 output.

    I am using the tone generator circuit show here:

    Help on the output circuit to switch a power transistor with the speaker
    would be appreciated.
  2. D from BC

    D from BC Guest

    Maybe a split power supply + class C? push pull power stage.
    IIRC..class C is without bias..
    D from BC
  3. mpm

    mpm Guest

    On May 30, 5:03?pm, "Infundibulum" <>
    ?I'd like to raise the power
    You could try a National Semiconductor LM4950 audio amp.
    Single supply, easy to hook up.
    Gain is set with programming resistors.
    Up to 7 Watts in bridge mono mode.

  4. Ross Herbert

    Ross Herbert Guest

    If you are using your ultrasonic sound generator for deterring dogs
    etc, a single tone may not be effective. A kit for a dog silencer as
    shown here uses a multiple frequency pattern
    and may be more effective and economical.
  5. GregS

    GregS Guest

    You will not get anything out until you apply a voltage source.

    I have used 18 volts for this type circuit, two 9 volt batteries.

    The piezo can take up to an equivalant 35 volts RMS
    If there was a way to push pull two 555's, that would be nice.

  6. GregS

    GregS Guest

    You can also use a transformer. You can use a 9 volt sorce and take the output
    to a Mosfet, and the mosfet can use 4 nine volt batteries, feeding the driver. A
    modified follower can be used, with a high value resistor on the bottom leg.

  7. Rich Grise

    Rich Grise Guest

    Why do you want power at 20 KHz? Dog whistle? Sonic weapon? Phlogistonic

    If it's to annoy dogs, please don't do it. It's not right to punish a dog
    for the negligence of its owners. If it's barking, use a water spray to
    shut it up.

  8. Rich Grise

    Rich Grise Guest

    It's not right to punish a dog for the negligence of its owner(s).

    If this is, in fact, about a barking dog, then make a tape recording of it
    and play it back at them when _they're_ trying to sleep!

  9. Marra

    Marra Guest

  10. Jasen

    Jasen Guest

    assuming you mean bridge, there is, hook trigger and threshold of b to the
    ouput of A, and reset to vcc

  11. Ross Herbert

    Ross Herbert Guest

    Yeah, that'd be right...

    That way the victim can get a double-dose of the annoying barking -
    which I am sure is just what he is looking for.
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