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Need help with Nixie (NL-840 tube) clock design

Discussion in 'General Electronics' started by Phil Nelson, Jan 13, 2006.

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  1. Phil Nelson

    Phil Nelson Guest

    So, we were out of state visiting relatives during Christmas week, then
    returned home to find still more relatives camping out at our place. They
    stayed for another week -- O joy :-(

    When with drooping eyes we stumbled in from the airport to celebrate the
    third (yes, third) Christmas gift opening, I found a handful of radio tube
    boxes in my stocking, jumbled around with mints, chocolates, and whatnot.
    "Cute -- garage sale crap," I thought, and put them aside.

    Today I got around to looking at the handful and discovered six NIB National
    NL-840 Nixie tubes, each including a base and matching IC chip.

    I guess my brother-in-law's challenge is to make a Nixie clock. (He is an
    actual "rocket scientist" -- a grey-haired guidance expert from Florida.)

    Also in the stocking, and perhaps these are unrelated stuffers, 10 NIB
    Miller coils: eight 3-10 mh (#9060), one 19khz (#1361) and one 38 khz

    Anyway, the draggers are drawn. I need an NL-840-based Nixie clock plan, and
    I need it now!

    The ICs included with the Nixie tubes have the following markings:

    NS8840N 122


    Phil "doesn't do solid state" Nelson
    Phil's Old Radios
    To send me email, kindly visit
  2. Eric Sears

    Eric Sears Guest

    Hi Phil
    I liked your story about the stocking stuffers! I just get old defunct
    cordless telephones etc from my rellies - I got a whole bunch together
    with a Motorola bagphone from my sister this year!!

    Anyway, I also inherited a bunch of Nixie tubes - I think the same one
    you have, together with the same I/C's (I recognise the SN7441) some
    years ago. These were together with some pc boards (about 1x1.5inch),
    and I THINK some sort of circuit for a frequency counter (not a
    clock). I believe the circuit was in about a 1960's or 1970's
    "Break-In" magazine (the mag of the NZART).
    Unfortunately, as I have just shifted house, finding it in a hurry it
    not feasible! But I will have a look around some time - hopefully I
    didn't dispose of them when I moved. I also have copies of the mags
    back to about 1960, so if I find time I will have a look.

    Best wishes

    Eric Sears ZL2BMI.
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