4215AB Wecovalve

The WECO valve or Peanut valve was an invention of H.J. van der Bijl of the Western Electric Co. in the U.S. in response to a request for valves of the lowest possible power consumption for use in the trenches. It was made by them in the U.K. and under licence by Mullard and BTH. The U.K. Western Electric Co. Ltd. was bought in 1925 by ITT who rebranded it as Standard Telephones and Cables - STC. Van der Bijl was a very skilled valve designer and had a reasonable claim to have originated the design of the 'TM' and 'R' type valves which were almost universal during WWI.

These were the first miniature valves. The filament drew 250 mA at 1 volt with an anode voltage of 15-30 volts for detection and 30-60 volts for other uses. Most of these valves, which were introduced in 1923, had 4 stud bayonet bases. This one, although marked on the envelope '4215A' is the unusual 4215AB on a British 4 pin base. It was introduced in 1924 and only made by Western Electric Co.