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Open Source ESR Tester (Looking for, don't have)

Discussion in 'Electronic Repair' started by Matthew Smith, Apr 9, 2005.

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  1. Hi All

    I'm sure that the Peak unit (and others) discussed recently are very
    nice, but could anyone point me to an open source ESR tester, or at
    least the principles required to build one.

    For one, I want to save money but at the same time, I really like to
    make my own kit where practical.

    Yes, I could go Google, but sometimes it's nice to get real
    recommendations from real people ;-)

    Cheers

    Matthew Smith
    South Australia
     
  2. mike

    mike Guest

    Use a time domain reflectometer.

    Just hook a scope to the cap and hit it with the fastest rise
    step you can muster. Keep it below half a volt amplitude so you
    don't turn on junctions. Stated another way, build your own TDR.

    If you know the source voltage and source impedance, you can easily
    calculate the ESR from the size of the initial step. You can also
    calculate ESL from the overshoot and capacitance from the time constant.

    Using this method, you know exactly what you're dealing with. You're
    not relying on some readout number that may or may not reflect what's
    really going on.

    mike

    --
    Return address is VALID but some sites block emails
    with links. Delete this sig when replying.
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  3. Ross Herbert

    Ross Herbert Guest


    Do you have access to Television & Consumer Electronics magazine?
    (This used to be Practical Television back in the old days). In Dec 04
    - Jan 05 issues they described an analog reading ESR meter designed by
    Alan Wilcox. This design operates in a similar manner to Capacitor
    Wizard but is not nearly so complicated and it is built on Vero
    stripboard. The only problem is that it specifies a Monacor PM-2/100uA
    meter movement
    http://www.monacor.com/int/en/produktseite_gesamtprogramm.php?artid=1762&spr=EN&typ=u
    which is not available in Australia. According to my research this
    meter is almost physically identical to the SEW
    http://www.sew.com.tw/model ST645 and this meter may be available in
    Australia, and hopefully the meter scale drawing in the article will
    fit without alteration.

    Contact me in private if you need more info. (remove SPAMEX)

    Ross H
     
  4. Fastvale

    Fastvale Guest

    order it here:
    http://www.nuovaelettronica.it/it/pop/index.cfm?fb=scheda_kit&w.kit_id=4899

    about 25 $ plus shipping.
    Absolutely performing!!!
     
  5. Bill B

    Bill B Guest

    Here's about as cheap as you can get, provided you have a 'scope. I use
    mine quite a bit and have had pretty good success. Look here:

    http://octopus.freeyellow.com/99.html
     
  6. Franc Zabkar

    Franc Zabkar Guest

    My local DSE store has Bob Parker's Mark I kit for ~AU$40. Only two
    left last time I checked.

    Otherwise try these:
    http://www.siliconchip.com.au/cms/A_103805/article.html
    http://www.siliconchip.com.au/cms/A_103243/article.html


    - Franc Zabkar
     
  7. Get the Bob Parker kit from Dick Smith or direct from Bob and you wont
    regret getting this great instrument. most of us Aussie techs use it.
     
  8. NSM

    NSM Guest

    In "PopTronics" (USA) July 2001, pages 25-28 there is a build it yourself
    design that uses a few common parts and has full protection. It claims to
    test in circuit from 1 uF on up.

    You may find copies at larger libraries under "Popular Electronics",
    "PopTronics" was a later name.
     
  9. mike

    mike Guest

    What do you actually use it for?
    Seems that every time I want to know ESR it's in a power supply or on
    a motherboard with a dozen hooked in parallel thru ground/power planes.
    I've had zero success finding bad caps.

    Out of circut, yes, but if you're gonna go to the hassle and board risk
    of removing the cap, might as well replace it. Half the time, have to
    pull the leads out and remove 'em one at a time from the ground plane.
    Holes are just too tiny to suck out the solder while the lead is in there.

    Over the decades, I've tried 35pS TDR to try to isolate caps.
    Tried spectrum analyzer with tracking generator to sweep power/ground
    planes while shorting caps to look for change.

    It's rare that there's only one cap, and with those, you can just look
    for ripple while it's operating.

    So what's the magic method for finding high ESR caps in-circuit in a
    typical situation of parallel caps?
    mike
    --
    Return address is VALID but some sites block emails
    with links. Delete this sig when replying.
    ..
    Wanted, PCMCIA SCSI Card for HP m820 CDRW.
    FS 500MHz Tek DSOscilloscope TDS540 Make Offer
    Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
    Wanted 12" LCD for Compaq Armada 7770MT.
    Bunch of stuff For Sale and Wanted at the link below.
    MAKE THE OBVIOUS CHANGES TO THE LINK
    ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/
     
  10. John Todd

    John Todd Guest


    I used a shunt ohmmeter cct. with the meter signal rectified
    and driven by a twin-T osc at 33KHz driving an LM386. Experiment with
    series resistor to get the meter range, and calibrate with resistors.
    Mine reads 0 to 75 ohms at about two-thirds deflection.
     
  11. Dave

    Dave Guest

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