Ever noticed these ancient Germanium transistors in TO5/TO39 case...

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  • eccerr0r
    Solder Sloth
    • Nov 2012
    • 8666
    • USA
    #1

    Ever noticed these ancient Germanium transistors in TO5/TO39 case...

    Anyone ever notice...

    Front - left to right
    2N1307 - PNP Ge
    2N1924 - PNP Ge
    2N1305 - PNP Ge
    2N3507 - NPN Si
    2N5320 - NPN Si

    Rear - left to right
    Unknown - NPN Ge
    2N329A - PNP Si
    2N5322 - PNP Si

    Why is this weird?

    All TO5/TO39's are E B C looking at the bottom when the center pin away from you.

    So this means, on the PNP Ge transistors, BASE is hooked up to the canister! Normally base is the high impedance signal (common emitter, emitter follower). I thought Germanium PNP transistors were used as common base as often as Silicon (not that often), hence this being weird ... or is it?
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    • PeteS in CA
      Badcaps Legend
      • Aug 2005
      • 3578
      • USA, Unsure of Planet
      #2
      Re: Ever noticed these ancient Germanium transistors in TO5/TO39 case...

      Back in ancient times I used the 2N404A when I was attending De Vry. It was probably obsolete by then, but I think De Vry did some sort of large scale lifetime buy at a really low price for use in their schools. I do not remember whether any of the leads connected to the case.
      PeteS in CA

      Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
      ****************************
      To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
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        Comment

        • eccerr0r
          Solder Sloth
          • Nov 2012
          • 8666
          • USA
          #3
          Re: Ever noticed these ancient Germanium transistors in TO5/TO39 case...

          Here you go, for old memory's sake. Well, not the "A" version... and another unmarked "npn" germanium.

          The bottom of the 2n404 is epoxy potted or something (or is it glass?) and the pins all appear to be isolated from the case.
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