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Help to identify National 14 pin DIP

Discussion in 'Electronic Components' started by Mark Storkamp, Dec 4, 2012.

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  1. I'm trying to reverse engineer a small circuit with a light detector
    that's used to set end-of-stroke on a mechanical slide. The circuit has
    a 7-pin header, three light emitter/detector pairs, two SIP resistor
    packages, and one IC. I need help identifying the IC. It's a 14 pin DIP

    It's labeled:
    1st line: (National Semiconductor Logo) 158 9129
    2nd line: SA 779197
    3rd line: 8201 CPA

    Anybody recognize this or know where I can get a data sheet for it?
  2. Ecnerwal

    Ecnerwal Guest

    You might want to look at the board, so as to see what might make sense.

    When I had quad emitter/detector circuits to play with in the 80's we
    were using an LM339 quad comparator. If the circuit looks like that
    might be it (with one quarter out of use) then it's worth a shot. If the
    pinout would not work for a 339, then that won't be what it is...
  3. Thanks. I looked up the pinout for that, but the power pins don't seem
    to be in the right spot for a LM339. Now I'm thinking it may just be a
    hex schmitt trigger. I buzzed out the lines to the header, and if pins 7
    and 14 on the chip are power, then pins 1 and 2 on the header are the
    power connectors. Pins 3 and 7 are not connected to anything, and that
    leaves pins 4, 5 and 6 as outputs, and they're on pins 2, 4 and 6 of the
    DIP. I'll probably just put 5V on it and see what happens when I block
    the light paths. I feel pretty sure it's just either totem-pole or open
    collector outputs. Worst that can happen is I just have to build a new
    one from scratch. What I don't understand is why they would use a house
    part number on something like this. This is surplus equipment, I don't
    know who the original manufacturer was.
  4. It keeps the customer reliant on the manufacturer. At the very least it
    means the parts come through the company so they get the profit, at worst
    they can raise the price and make more profit.

    It makes things a tad more difficult for someone to copy. It's no
    different than some companies sanding off the IC numbers. Someone
    tracing out the circuit has to work that much harder to figure out the
    circuit, and if they don't find the IC through guess and such, then they
    can't copy the circuit. It doesn't really stop those who have enough
    knowledge, but it does keep out the simpler ones.

    There was also a time when semiconductors weren't made as efficiently, so
    there'd be lots of failures or semifailures in a batch. Sometimes the
    manufacturer would put an official number on them, I'm thinking of the
    time when 64K dynamic RAM were new and there was a high failure rate, but
    it was limited to half the die. So they were perfectly normal 32K RAMs.
    I suppose in some cases they might just sell the batch to one company,
    with a house number, if the supply was such that a single company would
    buy it all up. I suppose then things like transistors might be offered
    ashouse numbered devices if they were out of spec, but a company that
    could live with the lower specs could make use of them. You don't want
    "bad" 2N706s to land in the hands of people who think they are full

  5. Guest

    IBM, too. Everything was house numbered and rarely did one group use
    parts from another. Many had very unique specs. One engineer I
    worked with spec'd an LF386 up to $30 each (put a tested limit on it
    recovering after being driven into the rails).
  6. Back when I worked for Fairchild/Schlumberger ATE we never used house
    numbered parts. (But then again, maybe we did. Most of the chips we used
    had Fairchild numbers and logos on them ;-)
  7. Guest

    We don't use many house numbered parts anymore. The things are too
    damned small to print part numbers on them. ;-)
  8. Guest

    Well, there is that. Good thing someone invented the Mantis.
    Laser? I thought it used electric fields.
  9. shrtrnd


    Jan 15, 2010
    I've got a bunch of those 158-xxxx parts, except they were all made by Texas Instruments.
    I never could find data on them, but noticed most went into military products.
    I assume they're a proprietary part number, made by several different manufacturers.
    I just don't know who owns the rights to the part numbers.
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