The DE3 is a general-purpose dull emitter triode that has a very delicate thoriated tungsten filament rated at 2.8V 0.06A. This exhibit dates from 1924.
The DE3 was one of the first British valves intended for operation from dry batteries but the battery required was a 4.5V 'bell' battery. This was used with a series rheostat adjusted by the user to provide approximately the correct running voltage across the filament terminals.
1.5 V cells made in the 1920s soon dropped to 1.0 to 1.1 volts, due to polarization, when used continuously as in a radio.
The wide glass tube envelope is 27 mm in diameter and excluding the B4 base pins, is 93 mm tall.
References: Datasheet, 4051 & 1003 Type DE3 was first introduced in 1924.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated September 04, 2013.