Source of Germanium transistors, old Ma Bell touchtone phone

[wa2ise]

Looks like that transistor used in the old touch tone keypads is Germanium. It measures around 0.25V BE and BC junctions with my DVM in diode mode. Though mine dated back to 1974, that should still be Germanium. It's PNP.



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I was a wrong number at the phone company...

[bob91343]

Is that a TO-66? Is there a type number on it? I have some old transistors like that.

[wa2ise]

Markings only say "12D" three times, and what looks to be a date code "2-74".

It's slightly wider than 1/4 inch diameter on the top, and slightly taller than 1/4 inch tall, not counting the leads underneath. Think it's a TO-5 package. The case is connected to the base, not the collector. It should do audio fine, but I don't know if it could do RF frequencies.

[bob91343]

Believe me, that is an audio-only transistor. Even when that was manufactured it was an old design.

Are you looking for a replacement? I have some TO-5 germaniums but doubt if any have base connected to the case.

I think I have some 2N425s for instance, if memory is correct. If you are seriously looking I will seriously look.

[wa2ise]

Originally Posted by bob91343

Believe me, that is an audio-only transistor. Even when that was manufactured it was an old design.

Are you looking for a replacement?

Thanks, but I am not looking to fix the touchtone pad. Just wanted to point out a possible source of Ge transistors for someone wanting to fix an old transistor radio.