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Editorial Consultant: Rod Burman

A Brief History of Valves

A Brief History of Valves

A Brief History of the Transistor

A Brief History of the Transistor


Image of OSRAM BARRETTER  ON GPO BASE, 1930's

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OSRAM BARRETTER ON GPO BASE, 1930's

Barretters are temperature sensitive resistors used for stabilising voltages in wireless receivers, usually powering the heater circuits, of AC/DC receivers.
Acting like a resistor but with constant current characteristics, a current over a particular range can be held constant over a range of varying voltage. A Barretter usually consists of an Iron wire held in Hydrogen filled glass envelope. Also used for many other applications.

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A0694

Image of GPO VT No 4 VALVE, 1920's

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GPO VT No 4 VALVE, 1920's

GPO VT No 4 Valve, a Triode of the 1930's on an American UV4 pin twist on base.

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A0640

Image of GPO VT32, 1925

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GPO VT32, 1925

Early Telephone Triode amplifier of 1925, with BPO twist on base.

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A0644

Image of CV257 MOV HOUSEKEEPER SEAL VALVE, 1943

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CV257 MOV HOUSEKEEPER SEAL VALVE, 1943

CV257 Triode Valve used in VHF power amplifiers, with the Anode connected by a Housekeeper seal (the copper disc), invented by A.A.A. Housekeeper, who solved the problem of bonding ductile metal to glass.

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A0673

Image of GEC TRANSMITTER POST OFFICE TELEPHONES, 1950's

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GEC TRANSMITTER POST OFFICE TELEPHONES, 1950's

GEC ACPT21 weight 36Kg's 665mm high 2Ft 2inch long hence the two handles for lifting. ACPT= Air Cooled Pentode Transmitter.
Transmitting Valve used by Post Office Telephones.

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A0215


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