| Western Electric 20D Transistor | |
| Written by AnubisTTP on 2025-03-16 |
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The Western Electric 20D is a 1.5W epitaxial silicon NPN power transistor. The 20D is packaged in a gold plated TO-38 canister with a creased lid and a top evacuation nipple. Two of the pins are bonded to the package with an airtight Kovar seal while the third pin, the collector, is welded directly to the transistor's shell. The 20D was primarily used as a high current switch in Bell System telephone equipment, and does not appear to have seen much use outside of the company.
Western Electric 20D transistor.
The 20D was primarily used as a high current switch in Bell System telephone equipment.
Western Electric 20D cutaway diagram and pinouts.
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