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homebrew sampling oscilloscope

Discussion in 'Electronic Design' started by Jorgen Lund-Nielsen, Sep 9, 2003.

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  1. Hello,

    a few years ago, in a magazine, there was a "design idea" to build a
    homebrew sampling oscilloscope with about 1 GHz bandwidth.
    Diode bridged input circuit, timing and so on.
    I lostthat article and Google find
    not the original article, only notes about it.
    anyone have a copy of it and will let me participate?

    Thanks,

    Jorgen
    dj0ud
     
  2. John Larkin

    John Larkin Guest


    A very good book is "Sampling Oscilloscope Circuits", part of the
    Tektronix Concepts Books series. They show up on ebay now and then,
    and the bookfinder services like Alibris can usually get them.

    The oldest samplers (1950's) used point-contact silicon or germanium
    radar diodes (1N34 types) and later Tek used point-contact GaAs. The
    original Lumatron and Tek (type N) samplers used an avalanche
    transistor pulser and a single-diode sampler; nasty.

    Lately, everybody uses tiny schottkies with capacitances in the 0.05
    pF range. Most modern samplers use two diodes in a half-bridge,
    although some of the Tek stuff is a 6-diode traveling-wave sampler.
    LeCroy, ever bizarre, has a 1-diode sampler at 60 GHz. I did a
    half-bridge for fun a few years ago, using commercial parts
    (step-recovery diode, shorted transmission lines as shaper, SOT-23
    dual schottky... basicly a crib of a Tek S2 head) and got about 5 GHz
    bandwidth. The timebase is more trouble than the sampler.

    I saw one magazine article that used an avalanche transistor pulser
    and a 4-diode bridge, at about 1 GHz; can't locate it now. The Tek
    7S14 works this way.

    Alex did a beautiful job of scanning the Tek 1S1 manual... all 24 megs
    worth.

    http://www.dfpresource.org/pdf/tek1s1_manual.pdf


    John
     
  3. Robert Baer

    Robert Baer Guest

    *GACK!* That is rather nasty on POTS; is ther a way to get the file by
    sending for a CD of it?
     
  4. John Larkin

    John Larkin Guest

    You could ask Alex; he posts here as AE.

    If I get a minute later today, I'll post some sampler front-end
    schematics to a.b.s.e.

    John
     
  5. A E

    A E Guest

    Nah, you rip the clock synth out of a PC and assume the rising edges are
    sub-nano and clean. :)
     
  6. Robert Baer

    Robert Baer Guest

    He was kind enough to e-mail me a link to a 15 page PDF circuit
    description by Tektronix; took about 5.5 minutes to fetch - much better
    than an hour *plus*.
     
  7. Robert Baer

    Robert Baer Guest

    Actually, the sampling speed - or more accurately, the bandwidth, is
    *easy* to determine.....
    Likewise effective signal sensitivity (eg: mV/cm).
     
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