Microphone Hummer (oscillator) 572-B

General Radio Company; Cambridge (MA)

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  • Year
  • 1933 ??
  • Category
  • Service- or Lab Equipment
  • Radiomuseum.org ID
  • 300903
    • alternative name: GenRad

 Technical Specifications

  • Main principle
  • Audio-Amplification
  • Power type and voltage
  • Direct Current supply (DC) / 6 Volt
  • Material
  • Metal case
  • from Radiomuseum.org
  • Model: Microphone Hummer 572-B - General Radio Company;
  • Shape
  • Chassis only or for «building in»
  • Dimensions (WHD)
  • 79 x 42 x 50 mm / 3.1 x 1.7 x 2 inch
  • Notes

  • This microphone hummer is a 1KHz oscillator which is similar in principle to microphone driven tuning fork oscillators.  It works by mechanically coupling a carbon microphone to an electromagnetically driven vibrator bar, adjusted to resonate at 1KHz.  It appears in the Heathkit IB-1 and IB-1B impedance bridges and supplies an approximately sinusoidal, 1 KHz signal for AC impedance bridge measurements.  A carbon microphone serves as the active element which drives the vibrator electromagnet, and through a transfomer supplies the 1 KHz electrical output signal.  A 6 volt DC source powers the carbon microphone driven vibrator electromagnet.

    The first and last years of manufacture of the 572-B are unknown, but the microammeter in the IB-1B has a manufacturing date stamped on the back: 22 November 1952.

    The 572-B schematic appears in the IB-1 schematic in the Heathkit manual.

  • Mentioned in
  • - - Manufacturers Literature (Heathkit IB-1 impedance bridge manual (circa 1949))
  • Literature/Schematics (1)
  • - - Manufacturers Literature (schematic appears in the IB-1 manual)
  • Author
  • Model page created by Gary Brandenburger. See "Data change" for further contributors.

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The model Microphone Hummer (oscillator) is part of the collections of the following members.

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