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Old 29th Nov 2021, 6:16 pm   #1
Skywave
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Question Choosing an LCR meter

Although I do have a few instruments for measuring L and C - separate ones for each type - they are now quite old, as in 30 years or more - and their calibration is somewhat suspect. In the meantime, or course, technology in this field has come a long way: integrated LCR meters, of which there appear to be many available by different manufacturers at widely different prices.

So, I'm asking for advice & recommendations: an LCR meter for less than £40, battery or a.c. mains powered.
All replies will be much appreciated; thank you.

Al. / Nov. 29th.
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Old 29th Nov 2021, 6:55 pm   #2
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Default Re: Choosing an LCR meter

For amateur use, just buy one of the cheap Chinese component analysers from an eBay seller. They are available cased and uncased - the uncased ones are perfectly usable and you can always fit them in a box of some sort. They start at about £10.
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Old 29th Nov 2021, 7:25 pm   #3
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Default Re: Choosing an LCR meter

I'll second Paul's advice, the Chinese testers seem pretty accurate and are very cheap. But a word of warning if you've not used one before - the chips in these can be instantaneously destroyed if you connect the tester to a larger undischarged capacitor. You can buy replacement programmed chips, but it's a hassle you can do without. But you have to look pretty hard to find any tester that won't be damaged in this way - I understand that most of the Peak models won't cope with it. They don't like it up 'em!

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Old 29th Nov 2021, 7:30 pm   #4
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Default Re: Choosing an LCR meter

At least if you blow one up you can just buy another one
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Old 29th Nov 2021, 7:40 pm   #5
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Default Re: Choosing an LCR meter

As always, you get what you pay for. The Chinese TC-1 type testers are within +/- 10% over a reasonable range of LCR values. And they can test other stuff - I find them handy for a sanity check on pinout of fets/bjts/diodes etc.

If you want more accuracy (like 1% or better) or multifrequency operation then you need to spend £100 or more (the sky's the limit) - so it all depends on what you want to measure, and for what frequency of operation.
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Old 29th Nov 2021, 9:39 pm   #6
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Default Re: Choosing an LCR meter

Well worth considering the popular MK328 Multi tester - LCR/transistors etc:

UK Suppliers:

https://www.ebay.co.uk/itm/193819085...IAAOSwbERdHGKP

(Cheaper from Banggood etc)

Worth reading this, regarding the MK328 LCR Meter v Peak Atlas:

https://www.vintage-radio.net/forum/...d.php?t=176122

The spec is attached.

(You don't always 'get what you pay for' - sometimes you get more).
Attached Files
File Type: docx MK328 TRANSISTOR AND MULTESTER SPECIFICATION.docx (16.3 KB, 69 views)
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Old 29th Nov 2021, 10:06 pm   #7
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Default Re: Choosing an LCR meter

David, correct me if I'm wrong, but the MK328 and the TC-1 are both copies of the same idea, described in:

https://www.mikrocontroller.net/arti..._.28English.29

and

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/

My comment about getting what you pay for is about LCR meter accuracy, not all the other (nice to have) measurement capabilities the atmega-based tester has.
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Old 29th Nov 2021, 10:29 pm   #8
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Default Re: Choosing an LCR meter

If you have a computer at your work bench, then a soundcard with some software like REW is a very convenient tool to have on hand, especially with a USB soundcard like a Focusrite 2i2. Although often used for audio bandwidth testing out to 90kHz bandwidth, it is an excellent LCR meter as it plots the impedance (magnitude and phase) over the circa 5Hz to 90kHz bandwidth, which can highlight a lot more about a passive part than just a single frequency measurement from a typical LCR tester. That is especially the case for passive parts that show up inherent resonance or phase shift characteristics within that bandwidth (even at the low frequency end for iron-core inductors and transformers).

Like modern VNA impedance analyser's, calibration only requires a reference resistor like a 0.1% 0.5W style, rather than also requiring reference C and/or L.

If you have a reasonable soundcard already then this is effectively a zero $ option to consider.
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Old 30th Nov 2021, 12:53 am   #9
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Default Re: Choosing an LCR meter

I know this is an expensive option, but it is designed and manufactured in the UK and with excellent specification

https://www.peakelec.co.uk/acatalog/...nce-meter.html

Note I don't have one (yet) but I'd sure like one.

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Old 30th Nov 2021, 10:30 am   #10
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Default Re: Choosing an LCR meter

Quote:
Originally Posted by Keith956 View Post
David, correct me if I'm wrong, but the MK328 and the TC-1 are both copies of the same idea, described in:

https://www.mikrocontroller.net/arti..._.28English.29

and

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/

My comment about getting what you pay for is about LCR meter accuracy, not all the other (nice to have) measurement capabilities the atmega-based tester has.
The original concept was developed by a 16-yr old German teenager who had seen the Atlas DCA55 Transistor Tester, (one of which I have, which performs less well than the MK28 incidentally), and decided to have a go at developing something similar. He goes by the name 'Coiltec' and his post (four years ago) the EEVblog at this link outlines the history of its inception. As can be seen, his idea wasn't 'stolen' by others, but was further developed from what was basically a transistor tester, into a fully featured LCR/ESR/Transistor tester:

https://www.youtube.com/watch?v=7Br3L1B80ow

He states:

Quote:

'I'm the creator of the original version of this tester; it uses an ATMega8 and a 2x16 character LCD as told in the video. I started this project in early 2009: After seeing a similar commercial tester (Atlas DCA 55), I thought it would be an interesting project to try building a similar device myself. As far as I remember (it's so long ago...), my first version could only detect bipolar transistors, diodes, MOSFETs and resistors. For this reason, I called it "Transistor tester". But the component detection - by only applying different currents by two different resistors on each pin and checking how the voltages change - worked far better than I had imagined'.

'I thought the project may be useful to others and decided to release it. I released the code completely free to everyone in a German microcontroller forum: At that time I was 16, was programming C for only about 2 years, and didn't even know about open source licenses. So it's completely OK for me that others make money of the project. I'm really pleased and impressed that this project got that popular and developed further by the community.

Many features shown in the video were added by the community and not by me: Inductor detection, Vloss and ESR measurement for capacitors, the battery voltage display, and several more. Since the community versions completely surpassed it, I stopped active maintenance of the original version at some point in 2012'.

End quote.

None of the LCR meters test below a certain range, for example capacitors below 30pF. However, to measure below that is simple. Just check the actual value of say a 100pF capacitor, then put it in parallel with the low value capacitor under test, read off the total value and subtract the higher value parallel one from the total.

I have two of the bare modules I bought for a fiver each some years ago, which I boxed up. Another one which was kindly gifted to me as a kit by a forum member, along with a 3D printed case, and have an actual MK328, which comes with a plug-in ZIF socket for use if preferred to the test leads. And I also have an aging 'All Digital Electric' L/C meter. They all give very similar results in terms of accuracy.

I'm not trashing other makes or models, but as a hobbyist, I can't think why I'd want to buy anything more expensive than an MK328, which - on 'shoot outs' - does better than others which cost three or four times as much. Same applies to multi-meters. Others may disagree, which is fine.

To calibrate it, you short the three test leads together and the display talks you through the steps.

One big criticism of the MK328 is the lack of instructions. If needed, the User Manual can be found at this link:

http://115.28.16.44:81/file/3533.pdf

Pic 1: Bare MK328 PCB (fully functional).
Pic 2: Complete MK328 as they come.
Attached Thumbnails
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Name:	MK328 Base PCB.jpg
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ID:	246982   Click image for larger version

Name:	MK328 MULTI TESTER.jpg
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ID:	246983  
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Old 30th Nov 2021, 11:54 am   #11
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Default Re: Choosing an LCR meter

I have Atlas and Der-ee LCR testers. The extra speed of the Der-ee is something. It's Taiwan-made:

https://www.deree.com.tw/de-5000-lcr-meter.html

It's around £100, but I believe there are copies out there. I can't vouch for how good the clones are. The Der-ee is an absolute joy to use: fast and accurate. My advice is to save up the extra dough and get a Der-ee. You won't look back. I can't remember when the Atlas was last used...
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Old 30th Nov 2021, 4:25 pm   #12
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Default Re: Choosing an LCR meter

Just out of interest, I measured several capacitors, inductors and resistors on 3 LCR meters I have: a HP4275A, which can measure impedance at frequencies of 10KHz to 10MHz; a DE-5000 which can measure from 100Hz to 100KHz and a TC-1 chinese atmega-based component tester. Caps and inductors were measured at 100KHz on the HP and DE-5000 with the exception of the 100uF which was measured at 10KHz.

The HP and DER meters were o/c and s/c calibrated before use; the atmega TC-1 has no cal capability. All readings were actual digits displayed.

Results:

Nominal value HP4275A DE-5000 TC-1
15pF 13.8165pF 13.90pF -
47pF 46.932pF 47.05pF 42pF
1200pF 1056.74pF 1056.9pF 1037pF
6200pF 6.1342nF 6.124nF 6.021nF
1.5uF 1570.8nF 1561.2nF 1555nF
2.2uF 2.2096uF 2.26uF 2.261uF
100uF 70.81uF 70.5uF 87.75uF

1uH 933.90nH 0.977uH 0.21ohm
10uH 8.3362uH 8.395uH 0.01mH
100uH 85.536uH 85.48uH 0.09mH
1mH 841.2uH 842.6uH 1.01mH
4.7mH 3.9952mH 3.994mH 4.1mH

10ohm 10.015 10.022 10.6
100ohm 99.936 99.81 103.8
1K 996.5 994.1 1001
10K 9.966 9.965 9.798
100K 99.36 99.33 103.1
1M 1.0024 1.0028 1.004
10M 10.056 10.063 9.814

From the above it can be seen that the HP4275 and DE-5000 are in pretty good agreement. The TC-1 is not able to measure accurately below 100pF and its inductance measurement capability is primitive but it is far from useless.
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Old 30th Nov 2021, 7:11 pm   #13
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Question Re: Choosing an LCR meter

Thank you all for your posts: informative & useful.

On e-bay there is the Proster BM4070 for sale at between £30 to £40 and I am tempted. Any thoughts on this particular item, please?

Al. / Nov. 30th.
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Old 1st Dec 2021, 11:14 am   #14
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Quote:
Originally Posted by Skywave View Post
On e-bay there is the Proster BM4070 for sale at between £30 to £40 and I am tempted.
Only £28.99 on Amazon and you can try it out and return it if you don't like it - can't get better than that!
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Old 5th Dec 2021, 4:13 pm   #15
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Default Re: Choosing an LCR meter

Anyone experienced with MASTECH ms5308? I'm divided between Der EE DE-5000 and this Mastech.
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Old 6th Dec 2021, 1:11 am   #16
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Arrow Re: Choosing an LCR meter

One BM4070 now ordered.

Al. / Dec. 6th.
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Old 8th Dec 2021, 7:37 pm   #17
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Default Re: Choosing an LCR meter

LCR meter now received.


This post is only for the purpose of reporting the results of an inspection and measurements I made to ascertain the functionality and accuracy of this instrument. Hopefully, other members will find it informative & useful. In this post, I use the letters L, C and R as convenient abbreviations for inductance, capacitance and resistance.

Brand.
This instrument was advertised as the manufacturer 'Proster'. On this item, that name did not appear: the abbreviation (or name?) 'SZBJ' was displayed. With regard to what follows, I do not know the relevance of that difference, (if any) but a survey of the www shows both are Chinese firms of a substantial size & appear to be professional. Obviously, there may be some close association between them.

Initial inspection.
This instrument came with an instruction leaflet. The English is very poor and confusing, particularly the sub-section on measurement of L.
This instrument features a 'set zero' rotary control (as would be expected). However, that control is only functional on the C ranges, which I found somewhat puzzling.

Measurement checks & assessments.
First, a bit of background is relevant & necessary.
When making a check on measurement accuracy & calibration on any instrument, it is obviously necessary to have 'known good' standards to use. I have two main instruments here which I use when necessary: an HP LCR meter, model 4332A; a Marconi LCR bridge, model 868B. Also a Hatfield decade R box and two Fluke DMMs. I have a range of L, C and R components whose values are known & which I keep in reserve for calibration checks only on those instruments - typically annually. Those instruments and components were used to check the calibration and accuracy of this newly-acquired LCR meter.

Measurement accuracy & results.
This instrument has a claimed accuracy of "x% +/- 5 digits"., were x is in the range 0.8 to 5 depending on which type of component is being measured and also the range selected. But I am a bit puzzled over the "5 digits" part. ( I can only assume that if a component is '100' in reality, in addition to the stated +/- x% error, '5' should be added, so that '100' will be displayed in the range 100 +/- x%, plus 5. )
R & C measurements were good: within the claimed accuracy. But there were significant errors in measurements of L.
Examples:
300 uH displayed as 360 uH; 400 uH displayed as 450 uH; 500 uH displayed as 570 uH; 320 displayed as 400 uH. These are only a few errors: there were many more in this range and also in the mH and H ranges.
The inductance of the test leads? A 'real' 10 uH coil displayed 10.7 uH; 2 uH displayed 2.0 uH.
Incidentally, I did consider if the R of any particular coil was relevant, but comparative tests ruled that possible confusing parameter out.

Conclusion.
In writing a report on an instruments such as this, there a much more that could be written, but the above will do as a 'starter' for any further possible discussion. In conclusion, I am somewhat disappointed: mainly on account of the L measurement. O.K., I can imagine someone saying: "But it was cheap compared to high-quality professional instruments, therefore . . .". Be that as it may: this instrument states its accuracy but for L, it falls sadly short.

Al. / Dec. 8th.
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Old 9th Dec 2021, 4:08 am   #18
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Default Re: Choosing an LCR meter

Not to say that the meter isn't just intrinsically inaccurate for L measurement, but for some ranges it may depend on its measurement frequency (assuming it uses just a single test frequency but maybe changes that for each range).

My 100uH grade 2 ref inductor measures dead accurate down to about 300Hz, but below that the REW software calculation has a harder time due to the dominant DCR of the inductor (0.54 ohm). If the measurement frequency was down at circa 100Hz, and possibly even 1kHz, then L values down at 300-500uH may be tough for that meter (given it may autorange to 20mH FSD ?).

For my 10uH grade 2 reference, DCR becomes dominant below 10kHz. So on the other hand if the test frequency is relatively high, then inductor first self-resonance may be a concern for that meter.
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Old 9th Dec 2021, 9:12 am   #19
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Default Re: Choosing an LCR meter

Most of the cheap LCR meters I've seen measure at about 300Hz. Which is fine for mH values but e.g. a 100uH inductor has an impedance of only 0.18 ohms. So it's hard to distinguish from the DC resistance.

Conversely a 100pF cap has an impedance of 5.3Mohm at 300Hz so again measuring small values is not easy.

Measuring low LC values accurately needs kelvin connections and the ability to choose a test frequency, but you can't really expect that on sub-£100 meters.
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Old 9th Dec 2021, 7:14 pm   #20
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Quote:
Originally Posted by Keith956 View Post
Measuring low LC values accurately needs kelvin connections and the ability to choose a test frequency, but you can't really expect that on sub-£100 meters.
I disagree. The design on any LCR meter must meet its stated accuracy if it's to be of any use. The price of the item must reflect the basic concept of high price: high accuracy; low price: low accuracy. Cannot have the best of both worlds.

Al.
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