Transistor Museum Early Germanium Power Transistor History by Joe Knight Delco

A SURVEY OF EARLY POWER TRANSISTORS

by Joe Knight

DELCO 1950/1960s GERMANIUM POWER TRANSISTORS

The race for the conversion of auto radios from tubes to semiconductors was no more fiercely fought than with General Motors' own Delco Radio Division. Delco advertised in early 1956 that they were already utilizing their power output transistors in some of the GM 1956 models, the Corvette being one of them. Delco had wanted something more powerful than the then 25-30 watt rating of the brand new TO-3 devices coming out so they developed a new TO-6 type device which was then rated at 55 watts dissipation.

TOP ROW, L-TO-R: The far right device is a rather chunky and heavy early developmental device with two heavy blade connectors, likely early/mid-l955 sometime, with the two connecting shell halves mated high up on the waist. The next two middle transistors, one intact and one cut open, again have the two halves mated high on the waist, likely late 1955. These now have the regular TO-6 type center mounted small threaded bolt with standard emitter and base pins on either side. The far right two items, the "A03" (likely late 1955), one intact and one cut open, although similar in design, now have the two metal shell halves meeting in the lower half of the waist. This is typical of all production Delco TO-6 designs from then on (see 2N174).

BOTTOM ROW, L-TO-R: The first two power transistors released by Delco were the 2N173 and 2N174, in early 1956. All these early devices were Germanium PNP types. For the first few years all germanium Delco devices had the usual paper ID tag with the blue background, up to 1960. The middle two devices, the 2N174A, was released by the end of 1956. The far right item, the 2N277, was also released by the end of 1956 along with the 2N278 and 2N290.

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Joe Knight Early Power Transistor History – DELCO