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AWESOME TESTING TOOL!

Discussion in 'Troubleshooting and Repair' started by niftynev, Jan 19, 2012.

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  1. niftynev

    niftynev

    22
    0
    Mar 20, 2010
    i've built a few of these now, for myself & for others. BRILLIANT for testing electrolytic capacitors! i've found it works on even higher voltage non-polarised caps down to about 470nF.

    it's called an esr (equivalent series resistance) meter. the esr of a capacitor is mostly more important than it's actual value( apart from in timing circuits, of course). the esr is kinda the the 'strength' with which a capacitor can hold a voltage stable.

    the only 'controls' are a pushbutton, although i've added a slide switch to make sure it turns off fully, & can't be accidentally switched switched back on by an unintended press of the switch. it has a 2 digit led 7 segment display, to show the reading. it will measure up to 100 ohms, & it will test plain old resistors too' up to 100 ohms. ther's a lookup table on the front of it, showing expected esr's of new capacitors of various capacitances & voltage ratings.

    it easily measures down to hundredths of an ohm! you can even zero out the resistance of it's test leads! the leads have a combined resistance of about 0.23 of an ohm!

    it automatically switches itself off if you don't use it for 5 or 10 minutes. it will also tell you if it's battery is getting low. as you may have guessed, this clever little device has a pic microcontroller inside it. there's even an updated version with self-fault diagnosis! the board it fairly closely packed with components, but it really was a pleasure to build.

    it doesn't work properly with inductors & coils, as it passes 'pulses' through whatever you're testing, & coils produce inconsistent readings.

    but the real beauty of it is that in 90% of cases, you don't even have to remove the capacitor from the pcb, as the electros in the circuit are usually the lowest impedance device. the other thing is that once you get used to using it, you can guess the approximate reading to expect from a given capacitor just by looking at it's physical size, regardless of it's value or voltage rating.

    yep, you might have guessed - I LOVE IT!!! - & I built it!

    it sits next to my multimeter, & is a most invaluable tool.

    it's a kit from jaycar electronics, from the silicon chip magazine.

    cost me less than 70 bucks too!

    if you're pretty good at soldering, & are involved in electronic repairs, i couldn't recommend it too strongly!
     
  2. shiekh

    shiekh

    77
    1
    Oct 11, 2010
    Any link to this ESR tester?
     
  3. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    I didn't really read everything you had to say, but based on this I wonder why you even brought it up? :D

    edit: and yes, you might as well offer up a link to something we can look at. I, like most people, like pictures...
     
  4. shiekh

    shiekh

    77
    1
    Oct 11, 2010
    If I had to guess, he might be referring to the ESR (equivalent series resistance) kit

    http://www.anatekcorp.com/blueesr.htm

    which looks fun to build, and would leave one with a very useful end product.
     
    Last edited: Feb 2, 2012
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,449
    2,809
    Jan 21, 2010
    NiftyNev, you need to learn what the ESR meter really does and what it's measuring. It's a great tool, but you need to refresh yourself on what it does and doesn't do and what the readings mean.

    They have nothing to do with strength, and using it on inductors and lower value caps give you predictable (but wrong) results.

    Actually it may be useful with inductors because it can probably spot shorted turns.
     
  6. shiekh

    shiekh

    77
    1
    Oct 11, 2010
    Unless...

    A low capacitance means a significant impedance from the capacitor and so introduces an extra voltage drop... unless perhaps one uses a sinusoidal probe, when the resistive drop is then in-sync with the probe, and the capacitive drop is 90 degrees out; if one were to then sample at the top of the probe wave, one might have a chance of not seeing the capacitive contribution. I think the Peak Atlas ESR tool might be better with low capacitance than most, possibly using a similar approach, and can be had for $130 with shipping (not much more than most home-brew alternatives).

    For shorted turns I think there is another cool kit by the same designer that looks at ringing (or lack thereof).

    http://www.anatekcorp.com/bluert.htm

    I think people would have fun building either of Bob Parker's wonderful kits.
     
    Last edited: Feb 2, 2012
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