Capacitance meter that goes to 1,000 mF ?

[Milacron]

The only multimeter I have that reads capacitance seems to be limited to 20mF readings. I've seen some cheap ones in the $20 range that supposedly read to 20,000mF....and yet most $40 ones seem limited to 20mF....so either the $20 ones are a misprint in the specs or they are of questionable accuracy.

Ideally a respected make that reads to around 1,000mF or so for under 100 bucks.... any out there ? One on eBay now that seems nice and reads to 9,999mF but $250.

 

[Bruce Griffing]

Just to be clear - people usually write uF for microfarads and rarely (but sometimes) write mF for millifarads. Millifarads is a unit used on some meters. Capacitors are rarely larger than 20mF. That is equivalent to 20,000uF. I do have some larger caps tho, and can understand the rare need to measure one. Are you sure you need to go that high?

 

[gary350]

What are you trying to do?

Do you want to test a capacitor to see if it is good?

Do you want to test a unknown capacitor to determine its value?

You can build a capacitor tester with an NE2 neon light buld, 1 resistor, and a DC power supply. It is a simple timer circuit first year electronic class. This circuit will cost you a whole $2 with sales tax.

By the way, I have a box of 30 capacitors all are 54,000 uf 200 VDC. all connected in parallel this gives me a total value of 1,620,000. uf at 200 VDC.

I also have 3 capacitors connected in parallel each capacitor in 210 MF 5000 VDC 18000 amp high energy storage capacitors. It holds a charge of 54,000. amps at 5000 volts. I can discharge this cap bank through 8 feet length of 1/8" diamete steel wire and it vaporizes the wire, produces a flash that is probably brighter that 500 arc welders and sounds like a stick of dynamite exploded. Lots of fun on the 4th of July and the police scratch their head trying to figure out if it is illegal.

 

[Milacron]

Just to be clear - people usually write uF for microfarads and rarely (but sometimes) write mF for millifarads. Millifarads is a unit used on some meters. Capacitors are rarely larger than 20mF. That is equivalent to 20,000uF. I do have some larger caps tho, and can understand the rare need to measure one. Are you sure you need to go that high?

Funny...I thought the specs writers for the Chinese multimeters were using mF for micro farad...since literally a "u" isn't correct....but then the correct symbol for micro isn't available on a standard keyboard. But you must be right as that explains the 20 vs 20,000 specs.

I just assumed 20uF was the normal limit as the one I have refuses to read beyond that, and I've lost the manual for it, so don't know what it's limit is supposed to be really. Bottom line, I want to go to 1,000 micro farad !

 

[Bruce Griffing]

If you want to go to 1000uf (1mF) you can easily do that with one of the import meters. I have one - I will post a photo if you want. It works well for me. I bought it because it went smaller than the meter I already had. It does go up to 20mF tho..

 

[Jim McIntyre]

Ideally a respected make that reads to around 1,000mF or so for under 100 bucks.... any out there ? One on eBay now that seems nice and reads to 9,999mF but $250.

Sounds like one of the Fluke 83 V meters. There's a new, but open box version on the bay for $199. That'd be my choice if I wanted a meter to have for a long time. I'm sure you've heard it before, but the Fluke handheld meters are the cream of the crop.

And yes, uF is commonly used for microfarad.

 

[The real Leigh]

Capacitors are rarely larger than 20mF. That is equivalent to 20,000uF.

Sorry, Bruce.

Caps are currently available up to 50 FARADS (50,000,000 ufd).

Capacities are so high now that they're putting them in standard D-cell packages and selling them as rechargeable batteries, competing with Ni-Cds.

To answer Don's original question...

Mouser ( www.mouser.com ) has the Fluke 77-4 for $250. It reads up to 100,000 mfd (that's microfarads, not millifarads). They have several other meters that go up to 10,000 mfd.

There's also a series of meters marketed under the name Meterman, from many different companies. These appear to be identical instruments, branded for whatever oem wants to pay for it. The model CR-50 is a capacitance/resistance/inductance meter with capacitance range to 20,000 mfd (microfarads). I have one of these and it works quite well, with very good accuracy. It's priced under $100, though this varies with the manufacturer and vendor.

edit... Hmmm The meterman stuff may not be available anymore. Other companies make comparable equipment. Try searching for "component testers" for specialized R/C meters.

- Leigh

 

[Bruce Griffing]

Leigh-
My reference to "rarely larger" is reasonable - I think. I did acknowledge that larger ones exist - even that I own some. But in the kind of equipment Don is trying to fix I think you could even say "very rarely larger".
BTW - I do remember when the first one farad capacitor became available. Quite some time ago as I remember. I am an old retired guy, after all.

 

[metlmunchr]

Somewhat OT, but what's the deal with the price of Fluke meters? I bought my 83 about 20 yrs ago for $145 including the optional zip up carrying case. Its probably twice that much now, while other similar electronic doo-dads that were $150 twenty years ago are more like $15 now. Is there some non-obvious reason, or is it just a case of maximizing the profits when you know you've got the best product of its kind? Which BTW, isn't a philosophy I could argue with at all.

 

[Benta]

You can measure larger capacitances by placing a known smaller cap in series with the large one and from the measured value calculate the value of the large cap. No need to buy a new meter.

Benta.

 

[clutch]

Refresh my memory, mmfd = ufd?

http://www.allaboutcircuits.com/vol_1/chpt_13/4.html

For an explanation of the post just before mine.

Clutch

 

[Just Bob Again]

Terminology has changed over the years. Also doesn't help that a lot of the cheap test equipment makers don't speak English. mfd and mmf are obsolete usage. mfd = uF = micro-Farad. mmf = pF = pico-Farad (or micro-micro-Farad). nF is nano-Farad (1000 pF). mF is the confusing one. If the F is capitalized, it's milli-Farad. If the f is not capitalized, as in "mf", it's improper usage. People generally mean it to be micro-Farad.

 

[Benta]

Clutch, good addition, I should have put the formula in.
If you use a known capcitor in series with the unknown one you can rearrange the formula in your link to get:

1/Cunknown = 1/Cmeasured - 1/Cknown

Example:
Cmeasured = 19.6 uF
Cknown = 20 uF

1/19.6 - 1/20 = 1/980 so the unknown large cap is 980 uF.

You should of course not trust what is printed on the "known" cap, but measure it first.

Benta.

 

[JL Sargent]

Yes, Fuke meters aimed at Engineering applications seem to have a low capacitance ceiling. Find you a Fluke meter aimed at the HVAC market and you'll have meter capable of your needs I suspect.

The Fluke 116 does up to 10K uf cap. and temp as well.

 

[deltap]

All the old residential AC guys carried a Cappy in their tool box made by SUPCO, Sealed Unit Parts Co. It is a dedicated tool for checking/measuring single phase alternating current motor capacitors. It has 2 ranges, 10uF and 10,000uF, and is low cost. Saw one on ebay for 7 bucks.

 

[WizardOfBoz]

...since literally a "u" isn't correct....but then the correct symbol for micro isn't available on a standard keyboard.

A way to get µ on the standard keyboard is easily available. This character, a Greek mu, is realized by holding down the alt key and typing 0181 (or, alternately, 230) on the numeric keypad. So we are supposed to remember that m stands for milli, and µ stands for micro. Grrrr.

Others here have pointed out that another convenient key sequence gives you the degree sign, °. This is either Alt-0176, or Alt-248.

I'm a Flukophile. I'd get a used one off ebay. The 87-Vs go for $100-250. Capacitance to 10,000 µF. That's 10mF.

By the way, if you think of what Leigh said (that larger caps are used for batteries), and if you think about how capacitance is measured (integration time, or, using AC input, measuring resonances in an LC circuit with a dip meter or measuring the current-voltage lag), you need to put significant energy into the large caps to measure their Farad value. This may be the limitation of small, handheld, battery-powerd units.

Best,

Jim

 

[The real Leigh]

So we are supposed to remember that m stands for milli, and µ stands for micro. Grrrr

That's correct per ISO standards, which have been used by the rest of the world for a long time.

Our problem here is that we invented this stuff, and the terminology developed many years before the ISO standards were written.

Remember cycles per second, which served us quite well before Hertz took over?

Regarding microfarads...
The letter u is no more correct as an abbreviation for micro than the letter m. The correct character is the lower-case Greek mu µ.

The m was used as an abbreviation for micro from the earliest days of the electronics industry (before 1920). This usage became more entrenched in the abbreviation mmfd for micro-micro-farad (ISO pico-farad). I have never encountered the abbreviation uufd in this context, although it may have been used.

As for generating Greek letters and other symbols, use the Character Map utility which is supplied with all versions of windows back at least to '98. Click on the desired letter(s) and it puts the proper code(s) in the clipboard.

Character Map is installed by default under Programs->Accessories->System Tools in WinXP.

- Leigh

 

[jim rozen]

Back in the olden days....

mfd = microfarad = 1e-6 farad.

mmfd = pf = picofarad = 1e-12 farad

and it was OK to have 1000 puff, and nobody
used nanofarads.

Jim

 

[WizardOfBoz]

The letter u is no more correct as an abbreviation for micro than the letter m. The correct character is the lower-case Greek mu µ.

I wearily agree, after recently having to go through a 20 page document a colleague wrote, and replace all the ug with µg. But if you have an old IBM selectric and you are typing labels for your cap drawers, it's probably ok to use ug.

Jim

 

[oldvan]

For those seeking more capacitence, here's 1500 farads....

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370076930494