Accuracy of Digital Capacitance Testers

Many digital multimeters also provide a capacitance measurement setting. I like the Fluke series of products. They make a very reliable series of meters at a variety of different price ranges. But as usual, you get what you pay for. I've never found that I've saved myself or my boss money by buying cheap tools.

I do not understand your comment about a reversing switch, or the peak up/down comment. I think you're thinking about a method to do a crude capacitor check using the ohm meter setting of an analog VOM, but I'm not sure. With a true capacitance meter capability this will not be needed. But the Fluke line does have in the ohm meter setting a bar graph display that can simulate this test when the capacitor value gets too large for the cap-meter range.

I use a Supco MFD10 meter for single phase motor work and have no complaints. It has detected cap faults where the analog lead swap did not.

The only drawback is you have to be sure to discharge the cap before testing.

They go for around $80.00.

I just love my DM-6013L digital capacitance meter (China, of course). It has a range of 20mf to 200pf, which is more than any others I found. And it was cheap, too! It came with nice little gators, and a cute little receptacle for small caps to just stab into. I think I got it on e-bay.

Please pardon my english, but what is ESR? also while i am at it what is GA?

Sorry for being so dumb

Joe

Hi Joe,

ESR = equivalent series resistance.

GA = Good answer...

Don't worry, we were all born dumb...

Cheers John

I too have found ESR values VERY useful in finding bad capacitors. I made my own meter from a circuit based on a TL062, which a friend found on the internet. It works great, and at low enough voltage that virtually all caps can be tested in circuit on board. I have both the circuit diagram and a PCB layout if anyone is interested... (also have a meter face for laser printing)

Oh hell yeah ! Please share ! My ESR meter is home made as well, but I made it over 10 years ago and have LONG since lost the schematic !!

Here you go. If these aren't readable, send me your email address by Private Message, and I'll send higher resolution copies there.

Here's the circuit:

and her's the PCB layout (single sided, inverted for laser printing using toner transfer to make the PCB).

Dick

Thank You VERY much !

These are perfectly readable.

Bryan

I just took a look and noticed that the PCB layout I posted is missing most of the Part ID's. After I finish a project I'm working on (Hopefully some time tomorrow), I'll correct that and post another copy.

I hope it is more or less obvious that Green is ground, Orange is unregulated DC in (7-15V), and Red is regulated 5VDC.

If you actually want to make one, A higher resolution copy would be preferred. I use the Toner Transfer process for making small PCBs. If you aren't familiar with the process, I can give more info...

Dick

OK, Here is the corrected PCB Layout:

The part numbers shown here correspond to the original diagram given in the earlier post, except that I added C8A (a 0.1µF bypass capacitor) and R12 (a load resistor, so the unit could be used with a digital voltmeter rather than a 50µA analog meter).

As I said, I got the circuit from the internet. I believe this is the original. The PCB layout is mine. I didn't have a TL062 on hand, but did have a TL072, and it worked fine. If I recall correctly, I tried several other dual Op-Amps having the same pinout, and all worked.

Note that all my capacitor locations have multiple pads to accommodate different physical sizes of capacitor, and the transformer pads were intended to provide considerable flexibility for different configurations of transformer. Good luck!

Dick

Thanks, That does make it clearer. I use the toner transfer method myself, and plan on importing the picture into paint shop pro , and reworking it myself anyway .

Thanks again !

Bryan

As I said, I can send it as a full size or enlarged PDF, to your email, if you wish. A sharper original will give a sharper final result. I can also provide it in black and white, which will print better.

Dick

Another inexpensive, but useful meter is an Extech MN26T. It costs $40 and here's the features as listed in the Mouser catalog:

Features:
• 4000 counts on large LCD with full function indication
• Measures AC/DC Voltage and Current,Resistance, Capacitance, Frequency and Temperature
• Temperature measurements to 1400°F (760°C)
• Duty Cycle, Continuity and Diode test
• Autoranging with manual range override
• Relative zero, Data Hold and Range Hold
• 10A fuse protection
• Overload protection and indication
• Auto power off saves battery life
• Includes protective rubber holster, temperature probe,two 1.5V AAA batteries and test leads CAT II - 600V

• 1 Year Warranty

FREE Temperature Probe!
A $13.00 Value!

Big John Mac,

I Have a Voltcraft-4090 LCR meter that I have used for several years now (purchased in Germany) that does 200pF - 200uF and 2mH - 200H. It seems to be quite accurate but does not do ESR.

I would also love to see DKWARNER's ESR circuit if he will post it.