I want to buy a capacitance test meter.

[Unionista]

I have a garage full of test meters from years of doing HVAC service but most of the multimeters cannot test for capacitance. I have one, a Fluke that does but it does not go low enough to test for picofarads. Another cheapie meter does go down to an nF scale but it seems to be wildly inaccurate at the lower scales. It was OK just for testing A/C capacitors. I looked at reviews of some meters on Amazon but most make no claims for accuracy. There are some claims for INACCURACY though. Others, even well-known brands, make no mention of pico-level scales. I end up with more questions than I started with. So my question is this- for those DIY'ers out there, what are you using when you have (or want) to test capacitors? Where do I go to find something decent that covers the full range needed for audio?

 

[droid2000]

I buy REL. They have the best capacitors. You can connect them to the speakers.

 

[restorer-john]

I suggest a DATS V3. It can do a ton of other useful stuff, is really compact, can work from any PC or laptop and doesn't cost much.

This is a 100nF Greencap. Took about 2 seconds. Can read from 1nF to 10mF.

Or go all out and try to locate a working Sencore LC-102 and pay the big bucks. If you need to test and match for high voltage caps (tube gear) this meter might suit you more. Trouble is, it's old and complicated and obsolete- but awesome. You don't want to be buying a non-working unit- they are an absolute nightmare to fix.

 

[Unionista]

I suggest a DATS V3. It can do a ton of other useful stuff, is really compact, can work from any PC or laptop and doesn't cost much.

This is a 100nF Greencap. Took about 2 seconds. Can read from 1nF to 10mF.

Right now, I need a device to measure picofarads. The DATS V3 doesn't go low enough. Also, after decades of using Linux and Mac computers, I don't even have a Windows computer in the house.

 

[mhardy6647]

The test leads become an issue for really low capacitance.
Unless one buys a true, calibrated and certified (traceable) test instrument (analytical tool), the issue of accuracy (calibration) is always gonna be "on the table", too.

Hard to beat a use test.

 

[Unionista]

Hard to beat a use test.

I remain unconvinced. There is not much "science" in trial-and-error. What's the name of this group again?

 

[LTig]

In 1997 I bought a HGL-2500 which should match your needs. AFAIR accuracy is 0.5% and the capacity of the leads can be accounted for by a calibration knob.

I don't know if it's available nowadays. I used it to match the filter caps of my DIY phono preamp and the resulting measured FR of +/- 0.03 dB from 20 Hz to 20 kHz is proof enough for me that it's good enough.

Edit: just found the manual. Accuracy is:
200 pF: +/-0.5% + 1 digit + 0.5 pF
2nf .. 200uF: +/-0.5% + 1 digit
2mF: +/-2% + 1 digit
20mF: +/-4% + 1 digit

Edit 2: The Peak Tech 3705 has similar accuracy.

 

[Unionista]

In 1997 I bought a HGL-2500 which should match your needs. AFAIR accuracy is 0.5% and the capacity of the leads can be accounted for by a calibration knob.

Edit 2: The Peak Tech 3705 has similar accuracy.

Thank you for the info & the link! I placed an order for that Peak Tech 3705. It looks to be exactly what I need. Thanks again!

 

[sq225917]

Peak lcr meter, UK company, mouser sell them

 

[amirm]

One of the most popular -- and the one I have -- is the DE-5000: https://www.amazon.com/gp/product/B00EBPOEAC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Its lowest range is 200 pf for capacitance. Note the specialized cabling that comes with it to make accurate measurements down low.

 

[amirm]

Thank you for the info & the link! I placed an order for that Peak Tech 3705. It looks to be exactly what I need. Thanks again!

You can't use those long leads to read small values. The meter I posted lets you insert the device directly into the meter.

 

[Unionista]

You can't use those long leads to read small values. The meter I posted lets you insert the device directly into the meter.

The PeakTech 3705 has two slots or holes for direct insertion. Unless you zoom in, they're difficult to see in the pic. They're about 7-8:00 near the range selector dial.

 

[Philbo King]

In my experience with capacitance meters, two 18 inch test leads will give you 50 to 120 picofarads. I used to have to tape the leads down to the bench to stabilize the reading, then do differential measurements to read low value capacitors. Like: "my taped down leads read 90 pf. Connecting the cap reads 135 pf. So the cap is roughly 45 pf."

Caps that small are generally useful in RF work, or for compensating op-amps so they don't oscillate.

Pro grade capacitance meters go to a lot of effort to "de-embed" the test fixture. That means the capacitor-holder fixture impedance is carefully measured, then the result is used to calculate what the capacitance reading would be without that impedance present.

If you really want to accurately measure very small caps, a Wein Bridge oscillator (or some other resonanct circuit) feeding a frequency counter would be far more accurate, though you have to do a little math to get the capacitance value.

Wien bridge oscillator - Wikipedia

en.m.wikipedia.org

 

[Unionista]

If you really want to accurately measure very small caps, a Wein Bridge oscillator (or some other resonanct circuit) feeding a frequency counter would be far more accurate, though you have to do a little math to get the capacitance value.

Wien bridge oscillator - Wikipedia

en.m.wikipedia.org

Do any lab-grade instruments manifest the Wein Bridge oscillator? The explanation was fascinating, especially that it was formulated in the 1920s and 1930s. It would seem that the value of any component would be super-critical and would thus affect the measurement accuracy. Or does the addition of negative feedback ameliorate that inaccuracy? Would it be worth it to construct such an instrument? Thank you for your time explaining this.

 

[radix]

A big difference is the one @restorer-john mentioned looks like it can do leakage testing at operating voltage. For SS, that might be 50 - 100V. For tubes, it could be 500V. (those are all rounded guestimates).

The inexpensive handheld meters will use a low-voltage test to get the capacitance. They can't do leakage testing. so, if you want to restore old equipment, you want something like that DATS.

 

[Philbo King]

The PeakTech 3705 has two slots or holes for direct insertion. Unless you zoom in, they're difficult to see in the pic. They're about 7-8:00 near the range selector dial.

Do any lab-grade instruments manifest the Wein Bridge oscillator? The explanation was fascinating, especially that it was formulated in the 1920s and 1930s. It would seem that the value of any component would be super-critical and would thus affect the measurement accuracy. Or does the addition of negative feedback ameliorate that inaccuracy? Would it be worth it to construct such an instrument? Thank you for your time explaining this.

The circuit using an incandescent bulb was developed by Hewlett (one of the founders of Hewlett-Packard) and was used for decades as audio and low freq RF generators.

TBH, there are probably better ways to do this digitally, considering a decent frequency counter runs $1000 or so...

Yes, all the frequency determining parts are critical. You should use caps with a very low temperature coeffient.

 

[valerianf]

A B&K precision LRC meter is able to measure at various frequencies.
www.bkprecision.com

 

[Unionista]

Well... unforeseen events have forced me to look at alternatives...

Dear Customer,

thank you very much for your order.

We unfortunately have to inform you that we will not be able to process your order due to dangerous goods.

We have cancelled your order.

Thank you for your understanding.


Best regards
reichelt elektronik

 

[LTig]

Dangerous goods????

 

[Unionista]

Dangerous goods????

I received that message as you see it (in English). I wondered if something was lost in translation.