Summary

Current regulator or barretter. Maintains a constant current of 200 mA with a voltage across it between 80 and 200 V. Used to regulate the heater current in AC/DC radios.
AC/DC radios were common in country areas of Australia where many towns had DC mains. For example Horsham only converted to AC in about 1948. Parts of the Melbourne CBD had a DC supply until the 1950s
Manufacturer: Philips, Holland.
Manufactured for Mullard, England.

A current regulator (ballast lamp or Barretter) uses an iron filament in a hydrogen atmosphere to produce a device through which the current is essentially constant over a range of voltages because of the large positive temperature coefficient of resistance of the filament. As the voltage goes up, the temperature rises, causing the resistance to rise, resulting in only a small rise in current.

Physical Description

Tubular bulb with 8 pin side contact base.

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