Handheld LCR meters, any good?

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There are now some handheld inductance/capacitance/resistance  
measuring tools that are comparable in price to a traditional
digital VOM.  Are they good enough to be of use in typical
troublshooting situations like motors, alternators and ignition
systems? In other words, no RF.  

Amazon has one for only $35, which seems hard to believe. One  
review notes lack of overload protection, perhaps explaining  
the low price, but still it's said to work reasonably well.  
Even if a unit with decent overload protection doubles the
price that seems inexpensive, if it really works.

My only experience with LCR measurements was with a General
Radio manual bridge probably built in the 1960's. Excellent,
but bulky.

Thanks for reading, and any guidance!

bob prohaska
  


Re: Handheld LCR meters, any good?
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Ebay has some for about $ 20.  I have one I bought several years ago and  
it works fine to give the value of the components.

A company called Peak is selling them for close to $ 100,but internally  
they are all about the same.  

I don't know what you mean by trouble shooting with them,, but for out  
of circuit test on components they are fine to tell if a component is  
good or bad and will show close to the actual value of the component.




Re: Handheld LCR meters, any good?
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Sounds like they're reasonably useful. By trouble shooting I meant simply
that the device is reasonably unfussy in use. It needn't be highly accurate,
and ideally should measure in-cicuit, but the latter is probably unrealistic.
In my case out-of-circuit measurements are apt to be the norm.  It's also  
helpful if the L and C measurements don't require a large Q value.

One thing that made me a little wary is the apparent lack of offerings from  
Tektronix and Fluke.

Thanks for replying,

bob prohaska
  

Re: Handheld LCR meters, any good?
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YOu can get them from about $ 15 to $ 50 depending on the case and if  
you want to get them direct from China or faster from someone in the US.
Even less if no case or leads.

The one I have is accurate enough to tell if a component is good or bad.  
Probably as good as any tester that is not lab grade.  They do not  
usually work in circuit.

They usually have 3 leads and you just hook them up in any order, use  
only 2 if that is all the component has.  Then press the button and a  
few seconds later it will tell you what is hooked to the leads and the  
value.




Re: Handheld LCR meters, any good?
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Any idea how the measurement is made? Everything I can think of  
starts with a step voltage and records voltage and current. That
 takes something akin to a DSO and waveform analyzer to sort out  
the circuit values. Seems incredible for less than $50.

Thanks for writing!

bob prohaska
  

Re: Handheld LCR meters, any good?
On Tue, 17 Mar 2020 01:52:23 +0000 (UTC), bob prohaska

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See youtube for lots of info on the cheap units, there are lots,
following similar design. They do not work on very low C or L values
thus can mislead if you are unaware - but otherwise unbeatable for
value. No incircuit at all, Bob Parker Blue ESR meter for that in Caps
only of course, but getting up the price scale. C+  

Re: Handheld LCR meters, any good?
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There is not too much to them. Mostly a microprocessor and software .

Look at this url.  You may have to hit the 'translate' to get it in  
English.

https://www.mikrocontroller.net/articles/AVR_Transistortester

The basic circuit is about $ 10 from China and the other cost is just  
the case and leads depending on what you want.

I think it cost me about $ 15 for the basic built circuit board with the  
2 line of 16 character display. I did put it in a box and added some  
leads.  It would have been usable as bought but I just did not want a  
bare circuit board laying on the bench. I am thinking of buying one of  
the more modern looking ones from China for about $ 25 or less.  Not  
sure if I will or not as I do not do that much any more and the one I  
have works fine.



Re: Handheld LCR meters, any good?
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Modern microcontrollers are able to do the voltage and current
measurements with minimal external components. The PDF for the
original open-source project that they're based on described the
measurement process in detail.

I had a look, but I must have deleted it. It's out there to be found
on the web with just a little bit of effort though.

If you find that project, it might be worth checking whether there's
a firmware upgrade available that the Chinese haven't bothered with.
That's the case for a similar open-source signal generator board
that's sold.

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Re: Handheld LCR meters, any good?
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I looked into these a while ago but didn't actually buy one (can't
remember my reasoning anymore). At that point the ones around that
price sold with a rectangular PCB with a fiarly large mono LCD
display mounted on it, were based on an open-source design that was
well documented in a PDF available somewhere on the web. That
described the circuit as well as the measurement performance.

I think you found the design by searching for the author's name. I've
long forgotten what that was now, and it isn't standing out in a
quick search for "DIY LCR meter". I probably still have the PDF filed
away some where. I'll try to remember to have a look sometime if you
haven't figured it out for yourself.

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Instead of a bridge, these use a microcontroller to time the
charge/discharge rate (there's a bit more to it than just a timer,
but that's the basic principle). This is a valid technique used in
many high-end LCR meters since the introduction of microcontrollers.
I don't remember the details of how well it was implemented in this
design, or how cheap Chinese components might affect the accuracy. I
think the original design was fairly decent though.

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Re: Handheld LCR meters, any good?
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I bought this one last year, it is more than $35, from this ebay  
seller:

https://www.ebay.com/itm/DER-EE-High-Accuracy-Handheld-LCR-Meter-DE-5000-bundle-TL-21-TL-22-AC-Adapter/312069448188?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

The reason why I picked this seller is his pack included the AC adaptor  
in the kit.

I've been extremely pleased with it.  To the extent I can tell,  
capacitance measurements are accurate, i.e., new caps measure to well  
within their tolerance specs.  Resistance measurments are close enough  
to my HP3468B in four wire mode that I consider them accurate (or else  
two fully separate meters are both identically offset, which I find  
unlikely).  I've not used the inductance mode enough to form any  
opinion.

Bad capacitors (i.e., the infamous swollen top variety) clearly show as  
bad.

It will do reasonable in-circuit measurments of capacitors (obviously  
depends on the exact circuit connections).

The unit, and the english language booklet (can be located via a web  
search) both state to discharge caps before measuring, which implies it  
has limited overload/input protection.

So far, for the small amount of troubleshooting I've used it for so  
far, I've found it to be quite useful to have.

In Jan.  I replaced the very short set of alligator clip wires in the  
alligator clip adaptor with a longer set of kelvin clip leads I picked  
up from an amazon seller.  That was a worthwhile modification.

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