dot on germanium transistor

Frequently asked question on transistors: types, substitutions, how to test, use and misuse them.
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Post by copachino »

what does it mean a red dot on the transistors?? i have seen many dealers that says that their transistor have a red dot, but im not sure what ir means

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Post by tonyharker »

A red dot or other colour dot on the side of the transistor case ONLY denotes the collector lead.
A red spot elsewhere on older transistors - usually on the top - used to indicate the goodness/gain/frequency response of the device. There were red spots - the best, white spots - good, and unmarked low gain. The manufacturing processes of early transistors was not as exact/precise as modern ones.

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