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I have a component I can't identify. It is a black plastic case component 1.4 x1 x0.7cm in size. Has three leads and what appears to be a hole in top where some black resin was poured in. Labelled as such:

6626 / P-B 72053 / 1 8 8

mystery component

Google searching the label returns junk results. I can't even guess what type of component this is, since the 3 leads have no appearant continuity or resistance between each other. I was told this was scrapped from a reel-to-reel computer.

Just so I'm not making a habit of asking questions I can answer on my own, and to help anyone else, Is there a preferred ident method or search engine I should try instead of google?

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    \$\begingroup\$ three pins, hole where something small was epoxyd behind? Probably an early commercial transistor. \$\endgroup\$
    – Marcus Müller
    Commented Nov 18, 2016 at 0:11
  • \$\begingroup\$ The top-hole is rectangular and there is a diag corner (notch) along the back right edge. \$\endgroup\$
    – meatydude
    Commented Nov 18, 2016 at 0:16
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    \$\begingroup\$ Maybe you should look at the computer's circuitry and try to guess what it is. \$\endgroup\$
    – Bradman175
    Commented Nov 18, 2016 at 0:42
  • \$\begingroup\$ resembles a part I remember in a 1966 radio from Japan but in house part numbers were common back then in the US \$\endgroup\$
    – D.A.S.
    Commented Nov 18, 2016 at 0:43
  • \$\begingroup\$ P-B, Potter-Brumfield? So maybe a reed switch. Or a surge-suppressor, to go across a relay coil. \$\endgroup\$
    – wbeaty
    Commented Nov 18, 2016 at 5:37

3 Answers 3

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Looks like a late 1950's/early 60's Germanium transistor. Use a multimeter in diode testing setting to figure out where the PN junctions are. You should see some 0.3V forward voltage across these, and in reverse, the multimeter should display an open circuit.

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  • \$\begingroup\$ my dollar-store multimeter detects nothing probing all directions, probably the component is destroyed. For reference, the multimeter is able to power an LED just fine. \$\endgroup\$
    – meatydude
    Commented Nov 18, 2016 at 0:27
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    \$\begingroup\$ It could also be a half-bridge rectifier. \$\endgroup\$
    – Janka
    Commented Nov 18, 2016 at 0:34
  • \$\begingroup\$ @Janka fair point, but these were pretty often well-marked with ~, + and - \$\endgroup\$
    – Marcus Müller
    Commented Nov 18, 2016 at 0:35
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I would guess this was made in mid-1966 (6626 is probably the 26th week of 1966). I think @wbeaty may be correct that it's Potter & Brumfield. That could also explain the three leads since it may be intended to connect across a form C relay contact.

P&B has been split up and sold through different hands several times over the years (Siemens, TE Connectivity etc.), so I would not expect anything on the net.

There are a couple of plausible things that would measure as open circuit with a simple meter and which were available in 1966. One is a dual RC snubber network, another is a dual varistor (MOV). Those hypotheses could be explored non-destructively, but not without a bit more equipment.

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The part could be a magnetic sensor from the "reel to reel" computer. Possibly a magnet mounted in a moving or rotating part of the machine was setup so it would go in front or over this part and activate a relay coil or reed contact switch inside.

A good plan for reverse engineering is to often take destructive steps and investigate the innards of the part.

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  • \$\begingroup\$ It doesn't react in any way (making a click or passing current) to a really strong (hard disk) magnet being placed on or moved across. \$\endgroup\$
    – meatydude
    Commented Nov 19, 2016 at 20:56

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