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Ultrasonic leak detecting apparatus

  • US 5,955,670 A
  • Filed: 11/15/1996
  • Issued: 09/21/1999
  • Est. Priority Date: 11/15/1996
  • Status: Expired due to Term
First Claim
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1. An ultrasonic detector comprising:

  • an ultrasonic transducer which produces an electrical output signal in the ultrasonic frequency range which is related to the intensity and frequency of received ultrasonic energy;

    a high gain charge preamplifier connected to said transducer and generating an amplified version of the transducer electrical output signal;

    a multi-level logarithmic attenuator receiving the output of the preamplifier and creating an attenuated version of the output signal of said preamplifier with at least one fixed reference point;

    a variable attenuator with an input connected to the output of the preamplifier and an output connected to the logarithmic attenuator, said variable attenuator including a fixed resistor connected to the input of the variable attenuator, a potentiometer connected between the resistor and a reference level, the wiper of the potentiometer being connected to the output of the variable attenuator;

    a frequency shift circuit connected to receive the output of the logarithmic attenuator and producing an audio frequency range signal related in magnitude and frequency to the attenuated signal, but shifted from the ultrasonic frequency range to an audio frequency range;

    an audio amplifier which receives the audio signal from the frequency shift circuit and amplifies the audio signal to create an amplified audio output signal; and

    a signal level indicator receiving the amplified audio output signal and providing an indication of the magnitude of the amplified audio output signal of the audio amplifier.

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