ESR Meter

[cpprioli]

Recently, I mentioned in another thread (in the General Electronics area) the use of an ESR meter in testing suspect capacitors. That reminded me of a project that I presented to a local "club" here in south Jersey, that the members of the group took on and built for themselves. It was a low-cost but fairly accurate ESR meter, shown below. (Note that since that meter was built, I severely shortened the test leads to reduce the effect of any capacitance inherent in the leads.) If anyone here is interested in possibly building one for your own use, I would be happy to post the assembly instructions, schematic and parts list, including test leads and enclosure. The meter is generally accurate on caps in excess of 100 pF, but as always when testing caps, it must be remembered that the cap MUST be discharged before testing to prevent damage to the meter.

The final cost of the completed meter is probably on a par with low-end factory-produced ESR meters such as the MESR-100, but the builder gets the sense of satisfaction with having built it yourself, as well as better understanding of its theory of operation. This also makes eventual troubleshooting and repairing the meter a snap.

If anyone is interested, post back and let me know, and I will then post the details. I didn't want to clutter the forum with details that may not draw any interest...

 

[Mickster]

Go ahead and post the details if you like, I'm quite sure it will be useful for some.
I have one of the GM328 variants that measure ESR, but am interested in seeing your project.

 

[dr pepper]

I built a near copy of homo luden's esr meter, its been ok I like the fact using a transformer it can deleiver reasonable current.
I'd like to at least see the schem of what you have done.

 

[cpprioli]

I'm gathering all of the documents together right now, for posting here. This too is a variation of luden's ESR meter, with refinements like a Gerber file set for the PCB and a complete parts list including vendor information. I'll be posting it here shortly.

 

[unclejed613]

i have a simple method of testing ESR, an audio generator with a 50 ohm output impedance, an oscope, and a spare pair of meter leads. connect the scope input to the output of the audio generator, and connect the meter leads also to the audio generator. put the generator on 50 or 100khz, and adjust the scope and audio generator controls to get full deflection on the scope. to get an idea what various values look like, use the meter leads to test some resistors between 1 and 30 ohms, and note the deflection on the scope for each one. use the test leads to test some capacitors, and once you get the hang of it, you will be able to visually determine what caps are good and which ones aren't. the way it works is that the generator, having a 50 ohm output impedance, forming a voltage divider with the caps under test. 100khz assures that almost anyelectrolytic cap will have a reactance of 1.6 ohms or less (usually the smallest common value for electrolytic caps is 1uF)

 

[dr pepper]

A geyser in LA who posts videos on tube radio/tv repairs just uses a audio source such as a phone and a audio amp/speaker and listens to the sourve through the cap, if you do it often the ear becomes good at diagnosing.
I'd rather have a meter I can put in my carry bag.

 

[Nigel Goodwin]

i have a simple method of testing ESR, an audio generator with a 50 ohm output impedance, an oscope, and a spare pair of meter leads. connect the scope input to the output of the audio generator, and connect the meter leads also to the audio generator. put the generator on 50 or 100khz, and adjust the scope and audio generator controls to get full deflection on the scope. to get an idea what various values look like, use the meter leads to test some resistors between 1 and 30 ohms, and note the deflection on the scope for each one. use the test leads to test some capacitors, and once you get the hang of it, you will be able to visually determine what caps are good and which ones aren't. the way it works is that the generator, having a 50 ohm output impedance, forming a voltage divider with the caps under test. 100khz assures that almost anyelectrolytic cap will have a reactance of 1.6 ohms or less (usually the smallest common value for electrolytic caps is 1uF)

Expensive way to test ESR

The later types of cheap component testers you can buy as kits from China test ESR as well now, not as good as a proper ESR only meter (particularly for in-circuit testing) but probably all most people need, and EVERYONE should have one, they are such useful little devices, and great fun to build - I think I've build five different ones now

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[gophert]

I think I've build five different ones now

What kind of work do you do that results in so many capacitors with questionable ESR values that need 5 ESR measurement devices?
I have a lot of different voltages in different locations so I have several DMMs but 5 ESRs? Seems like there's an interesting niche workload behind that.

 

[Nigel Goodwin]

What kind of work do you do that results in so many capacitors with questionable ESR values that need 5 ESR measurement devices?

I don't, they are for general use as component testers, I've got 5 because I enjoy building the kits I use one of them at work.

I was considering ordering a 6th one when getting the link yesterday, as there's some new varients around!.

In my previous career I tested thousands of capacitors though, using an ESR meter multiple times every day - but I've got a specific ESR meter for that purpose, prior to the Chinese component testers appearing. Almost all electronic faults on domestic equipment were down to high ESR electrolytics, I had drawers full of high quality ones to replace them with (the failure is down to fitting sub-standard capacitors during manufacture).

The classic example was Samsung, who fitted capacitors in their TV's, and PSU's they built for Thomson Sky HD boxes, that had a rated life of between 10-12 months only according to their manufacturers datasheet. The result was that all Samsung TV's for about five years had no spares available after the intitial 6 months of use, as they had all been used for warranty repairs.

I have a lot of different voltages in different locations so I have several DMMs but 5 ESRs? Seems like there's an interesting niche workload behind that.

No, just fun

I too have several multimeters, and scopes as well.

 

[dr pepper]

I have 3 component testers, and 1 esr meter, maybe soon to be 2, thinking of building a real simple one with a 555.

 

[cpprioli]

OK -- I finally found the time to gather everything together and assemble it for uploading. As I said earlier, this is an enhanced variation of luden's basic ESR meter. There are two files. The first file is a complete manual including detailed assembly instructions, parts list, schematic, scope traces, and enclosure and meter templates. The second file is a .ZIP file containing the Gerber RS-274x file set for fabricating the PCB for the meter. Let me know what y'all think...

 

[dr pepper]

Very well done, and comprehensive.

 

[unclejed613]

Expensive way to test ESR

not if you already have the equipment...