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Thread: Nixie clock?

  1. #1
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    Default Nixie clock?

    Curious what this is:

    https://rover.ebay.com/rover/0/0/0?m...2F264279009354

    I was guessing Nixie clock... minus the digits for seconds, but I see it has an edge connector and may be part of something else?

  2. #2
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    it's probably a 4 1/2 digit meter
    there are no colons, the horizontal neon on the left would be for minus

  3. #3
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    My guess would be a counter/meter of some sort. Lots of old Moto and Fairchild RTL ICs from the late 60s/early 70s.

    You'll probably have to go to bitsavers for old Fairchild and Moto IC databooks on these. The Sprague hybrid packages are an unknown to me.

  4. #4

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    I'm going with DVM. You can see in the analog part, there are what looks like two transistors tied together with a tiewrap. This is most likely a differential front end amplifier. From the age, I'd suspect it is a single slop DVM. The patent I found for the dual slop was patented in 1975. The parts look to have date code for 1970 and at least one 1969.
    Dual slop were much better since the quality of the oscillator was less of an issue. As long as it had good short term stability, differences in the rate were compensated by the dual slop action. It also had the ability to do auto zero that made it especially useful for thermal couples. It did have the problem that if a count over ranged and the circuit didn't completely the count down, it would mess up the auto zero for a number of counts. The dual slop significantly improved the DVMs. It only required a stable voltage reference and could use cheaper capacitors for the integrators and other parts. Single slop needed significant warm up stabilization time and better quality parts to get the same accuracy.
    Dwight

  5. #5

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    The 724 opamp and the capacitors near it are also what you'd typically see in a single slop ADC.
    Dwight

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    AMAZING BOARD? It looks pretty humdrum to me.

    It does look much like a typical DVM, though usually you can see banana jack sockets, and not normally edge connectors.

    Clocks used to be the exception, not the rule, for Nixie tubes. The vast majority were used for numerical position readouts. The next biggest use was for electronic test equipment, and then monetary figures.

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  8. #8
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    Looks like a self-contained Nixie Display Module. Give it power and an input for the segment drivers and then you didn't need to develop your own display system when building your equipment.

    Edited: I have a similar module with just an edge connector on the back.

    = Excellent space heater

  9. #9

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    I think that it’s a Kay DVM or panel meter.

  10. #10

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    If you look at the Sprague ceramic modules, you see that these are likely divider resistors. The edge connector would likely go to a panel with a selector switch and test lead jacks.
    If used as a generic panel meter the edge connector would likely go to a connector strip where one could jumper the input resistors for that particular application.
    In any case it is a digital meter.
    Dwight

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