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anyone make a cheap cap tester?

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  • anyone make a cheap cap tester?

    I have 2 meters with cap function, but my fluke's never reads the darn things and my other one does but is always off by a good 50% or more. 100pf reads 180pf for example. I really CAN do without this, but i'd like to have it. Hence the request for a cheap one.

  • #2
    Like everything else it's probably cheaper to buy one rather than DIY from scratch. Before I got my 179 I bought a cheap one from CE under $40. Works as well as the Fluke, IMO.

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    • #3
      Originally posted by T9c View Post
      Like everything else it's probably cheaper to buy one rather than DIY from scratch. Before I got my 179 I bought a cheap one from CE under $40. Works as well as the Fluke, IMO.
      Thats not too reassuring to me since my fluke's cap function is virtually worthless. Whats this about making one tho? I'll have to google that.

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      • #4
        I've got an old B&K cap meter that does great with reading capacitance but doesn't do ESR. When I compare it to my Fluke the values are close, but the B&K reads far faster.

        When doing cap readings, especially at low pf values remember that the leads alone can add a lot of capacitance to the readings.

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        • #5
          Originally posted by 52 Bill View Post
          I've got an old B&K cap meter that does great with reading capacitance but doesn't do ESR. When I compare it to my Fluke the values are close, but the B&K reads far faster.

          When doing cap readings, especially at low pf values remember that the leads alone can add a lot of capacitance to the readings.
          True, but if the leads are long enough i unplug the probes and stick the cap right in the meter jacks. Still reads way high, tho not as much. About 50% higher instead of 80%

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          • #6
            I built the Dick Smith Electronics K-7214 kit an ESR meter which can measure in circuit providing the cap is discharged.
            It doesn't however measure capacitance but indicates the ESR (Equivalent Series Resistance which basically tells how well the capacitor in question acts like a capacitor.

            ESR meter page

            It satisfies my curiosity more than anything as practically considering caps are so cheap , I find it easier just to replace a suspect rather than frig around measuring stuff.
            Sometimes the results are surprising , for example some cheap "foreign" (racism is such a curse) caps have better readings than reputable brands.
            I recently recapped a Fender combo (brand new I might add) at the request of the owner, I was dubious that it would make much difference particularly as it came from the Fender Custom shop but I ended up a bit gob smacked and feeling naive !
            Maybe the gossip on the internet has some truth to it after all .. no wonder there is a growing market for hand made reproductions of the "Golden Oldies" pre CBS Fender clones.
            I do have a cap test on my multimeter I soldered some alligator/crocodile clips to banana plugs to eliminate stray capacitance and most of the time the readings are in the ball park. Very rarely do I find cheap and accurate in the same sentence when buying test gear !

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            • #7
              I don't like to support China sales but this meter actually works.
              Put mine in a little aluminum project box & added a 5VDC cell phone charger wall wart to power it instead of the USB cable provided. Can be found on the money laundering site ebay! Shop around, prices vary.
              Click image for larger version

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              • #8
                Originally posted by SHORT EDDY View Post
                I don't like to support China sales but this meter actually works.
                Put mine in a little aluminum project box & added a 5VDC cell phone charger wall wart to power it instead of the USB cable provided. Can be found on the money laundering site ebay! Shop around, prices vary.
                [ATTACH=CONFIG]21833[/ATTACH]
                My god, i checked ebay and there are tons of cheap meters ! But i can't imagine they could be very good as cheap as they are. I'd really like to know how they make any money on the $10 ones that ship from china !!!

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                • #9
                  I built one from this kit and it works fine.

                  Capacitance meter KIT

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                  • #10
                    Originally posted by Kazooman View Post
                    I built one from this kit and it works fine.

                    Capacitance meter KIT
                    Hmmm....can you tell me, is the 1% accuracy it boasts true? Because if so i definitely need one of those. Any "gotchas" with the assembly?

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                    • #11
                      Originally posted by daz View Post
                      I have 2 meters with cap function, but my fluke's never reads the darn things and my other one does but is always off by a good 50% or more. 100pf reads 180pf for example. I really CAN do without this, but i'd like to have it. Hence the request for a cheap one.
                      That sounds about right - - you are reading the capacitance of your test leads plus the value of the cap. If you always use the same leads, you can get reasonable accuracy by just subtracting off the value the meter displays when the leads are not connected to the cap.

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                      • #12
                        Originally posted by daz View Post
                        Hmmm....can you tell me, is the 1% accuracy it boasts true? Because if so i definitely need one of those. Any "gotchas" with the assembly?
                        Well, I can't vouch for their claim. I mainly use it to check cap values when the markings are not crystal clear or to check an old cap that I want to reuse or suspect may have gone astray. 10% would be fine for me.

                        There is nothing to the assembly. All of the difficult stuff is already done. You just add the resistors and a few other things.

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