Without markings our identification has to be probable rather than certain. The format of the wire in the envelope suggests a barretter current stabiliser.

Barretters were a Continental invention, being used by the Germans to control valve filament currents during WW1.

This specimen looks typically Philips and 1930s, and may be identifiable by the number written on the pinch.

The wide glass tube envelope is 38 mm in diameter and, excluding the B4 base pins, is 108 mm tall.

This exhibit was last updated on 02 March 2005