AvoMeter (AVO Meter) 1

Avo (Brand), Automatic Coil Winder and Electrical Equipment Co., Avo Ltd; London

Datos
Foro
Imágenes
Colecciones

  • Año
  • 1923
  • Categoría
  • Aparato de medida y servicio (Equipo de laboratorio).
  • Radiomuseum.org ID
  • 293873

Haga clic en la miniatura esquemática para solicitarlo como documento gratuito.

 Especificaciones técnicas

  • Gama de ondas
  • - no hay
  • Tensión de funcionamiento
  • Pilas / 3 Volt
  • Material
  • Madera
  • de Radiomuseum.org
  • Modelo: AvoMeter 1 - Avo Brand, Automatic Coil
  • Forma
  • Sobremesa de cualquier forma, detalles no conocidos.
  • Ancho, altura, profundidad
  • 6.75 x 8.25 x 4.5 inch / 171 x 210 x 114 mm
  • Anotaciones

  • The first Avometer was designed and patented by  Donald Macadie & introduced in 1923;

    • DC 12, 120, 600 volts - sensitivity 12 mA
    • DC 120 mA, 1.2, 12 A
    • R 10k ohm (225 ohm centre)

    The Avometer is a portable high-class combination electrical measuring instrument that has been designed by, and is manufactured for, the Automatic Coil Winder & Electrical Equipment Co., Ltd., of Wellington House, Buckingham Gate, S.W.1, to give direct accurate readings of current from 1 milliampere to 12 A; of pressure from 0.1 to 600 V; and of resistance from 0 to 5,000 ohms.

    Comprises a moving coil with a resistance of 20 ohms, wound on an aluminium holder and pivoted steel points resting on jewels; the coil moves with narrow gaps between the poles of a powerful magnet. A knife-edge pointer is fitted to the movement, and two non-magnetic hair springs convey the current to the coil and torsionally return the pointer to zero.

    The dial is provided with an inset mirror to prevent parallax errors and is marked in two scales. The top scale is calibrated to read direct in ohms from 0 to 5,000, and the bottom scale is divided into 120 divisions, each approximately one millimetre in length, for reading the various values in amperes and volts. The moving coil is permanently shunted by means of wire wound on flat non-conducting material. To minimise the heating effect, when heavy current is being measured, use is made of a very heavy gauge of wire on a portion of the shunt. Another portion of the shunt is wound on a semi-circular holder, and by means of a sliding contact arm, the connection is obtained at the desired point, thereby acting as a potentiometer in the ohmmeter circuit.

    The polished oak case is provided with a leather carrying handle, and the switches and terminals are mounted on an ebonite sheet on the lower portion of the face. All contacts are made inside the case, which is completely dust proof. The switch governing the different scales is provided with a spring click, operating at each stop, and the rheostat and adjusting switches are clearly marked.

    The rheostats are of special design, wound on well-insulated metal holders, which allow for heat to be quickly dissipated over a large surface. With constant use, the ohmmeter battery should last at least 12 months, and it can be replaced by another inside of one minute. The various circuits of the Avometer are so connected that there is no danger of obtaining incorrect readings due to faulty contact in the shunt circuit. The movement is practically “dead beat,’’ and the meter covers wide ranges of electrical measurements by simply turning a switch, which hitherto could only be made by the aid of several expensive instruments.

    Means are provided for compensating any variation in the voltage or internal resistance of the battery inside the instrument.

    The dimensions of the instrument are 8¼ x 6¾ x 4 ½ in., and its weight is 6½ lb.; patents have been granted, or are pending, throughout the world.

    The Electrical Review Aug 10, 1923, Page 281

  • Peso neto
  • 6.5 lb (6 lb 8 oz) / 2.951 kg
  • Mencionado en
  • -- Original prospect or advert (The Electrical Review Aug 10, 1923, Page 281)
  • Autor
  • Modelo creado por Gary Cowans. Ver en "Modificar Ficha" los participantes posteriores.

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