Cambridge Thermionic Voltmeter Type B

Cambridge Scientific Instrument Co.; Cambridge

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  • Year
  • 1928 ?
  • Category
  • Service- or Lab Equipment
  • Radiomuseum.org ID
  • 357590

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Tubes
  • 1
  • Valves / Tubes
  • Wave bands
  • - without
  • Power type and voltage
  • Dry Batteries / 70 4 Volt
  • Loudspeaker
  • - - No sound reproduction output.
  • Material
  • Various materials
  • from Radiomuseum.org
  • Model: Cambridge Thermionic Voltmeter Type B - Cambridge Scientific
  • Shape
  • Tablemodel, with any shape - general.
  • Notes

  • Cambridge Thermionic Voltmeter, Model B, was developed to complement the Model A.

     It addressed the limitations of Model A to meet a broader set of measurement needs. The key differences between the Type A and Type B Cambridge Thermionic Voltmeters (Moullin Voltmeters) are:
    1. Voltage Range:

    • Type A: 0 to 5 volts
    • Type B: 0 to 10 volts

    2. Circuit Design:

    • Type A: Does not use an anode battery. The filament battery supplies both the filament current and the negative grid bias.
    • Type B: Uses a separate anode battery and applies negative grid bias through a high resistance.

    3. Input Impedance:

    • Type A: Requires an external conducting path between grid and filament.
    • Type B: Can be used where there is no conducting path between grid and filament.

    4. Precision:

    • Type A: Scale is divided to 0.02 volt over most of the range.
    • Type B: Can be read accurately to 0.5 volt.

    6. Application:

    • Type A: Suitable for very low voltage measurements with high sensitivity.
    • Type B: More suitable for higher voltage measurements and in circuits without a direct grid-filament path.

    Both types use anode-bend rectification, relying on the curvature of the anode-current grid-voltage characteristic for their operation. The Type B model appears to be more versatile in terms of circuit compatibility and voltage range, while the Type A offers higher precision for very low voltage measurements.

  • Mentioned in
  • Elektrische Gleichrichter und Ventile, Prof. Dr.-Ing. A.Güntherschulze of the Physikalisch-Technisch
  • Author
  • Model page created by Wolfgang Müllner. See "Data change" for further contributors.

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