A SURVEY OF EARLY POWER TRANSISTORS

by Joe Knight

THE POWER TRANSISTOR

BELL TELEPHONE LABS AND WESTERN ELECTRIC

By 1953, Bell Labs was looking to develop a compact medium-power device for use on the telephone system circuit boards. This lead to the BTL 1854 PNP Alloy Junction Medium Power Transistor, released in 1954, shown below on the left. While rated at 1/4 watt of dissipated power (the common threshold for 'power transistor' status) it was just a standard, but taller, hermetically sealed transistor device, like that shown next to it, also from 1954. The BTL 1854 was designed to be clamped to a heat sink on a circuit board, allowing for greater power dissipation.

The above RETMA three color-code dots (gray, green and yellow) identifies this device as a "854", while the first missing digit was always understood to be a "one". Next to it can be seen a normal height WE transistor case. The barely discernable green dot on the 1854 right side indicates it is a PNP device.

Go To BTL/Western Electric Early Power Transistors, Page 10

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Joe Knight Early Power Transistor History – BTL/WESTERN ELECTRIC  Page 9