Fnirsi LCR-P1, $30 LCR tester (August 2024)

[mawyatt]

There seems to be many misconceptions/misunderstandings about Capacitor ESR, this is just a parameter that helps describe the capacitors loss in a simple 2 element capacitor series model, C + ESR, or 3 element series model C + ESR + ESL. ESR simply lumps all the capacitor losses into one simple parameter, similar to Capacitor "Q" which represents overall "Quality" which shows relative Reactance/Rloss, or 1/(omega*C*ESR).

Unfortunately ESR is a highly dependent variable with frequency, waveform type, capacitor type, value, applied voltage, temperature, age, history and so on, which often prevents one from precise results, and makes it difficult to pin-down a specific reading with any confidence. Some capacitor types have a more repeatable ESR measurement, such as some large value PP Film types.

ESR tends to be low values which place importance on cables/fixture, setup and calibration (Zero/Short specifically), which adds additional uncertainty in measurement.

However, ESR measurement is not all Black Magic, as one can achieve respectable results with good engineering practice. First off, one needs to KTI (Know Thy Instrument) and how the results displayed are created. Significant differences exist in operation between the low-cost All-In-One Testers and LCR Meters, even between LCR dedicated instruments themselves!!

One also needs to understand the DUT under investigation. For example, ESR is highly temperature dependent in most large value Electrolytic/Polymer Capacitors. During measurement Lab Grade LCR Meters can produce significant DUT current, often greater than 100ma RMS!! This current heats the capacitor internally by means of I^2 *ESR which changes not only the Capacitance but also the ESR readings. One can experience this effect by simply watching the Capacitance  and ESR readings change as time moves on, and should wait for these to stabilize for a more repeatable result.

Since low Z values are present where ESR is usually of concern, setup and fixtures play an import part in achieving repeatable results. One should study the various resources (some on here) for these and become intimately familiar with if repeatable results are expected.

Calibration is extremely important for quality repeatable measurements of any kind, especially true for Short/Zero Calibration for Low Z, ESR is no different. Lab Bench LCR meters often have an extensive Calibration Routines which should be employed, and some fixtures require specialized means for Calibration. For example the popular Leaded Component Fixture such as the Tonghui TH26048A has a specialized Zero Metallic Blade TH26010 for quality Zero Calibrations.

Anyway, the general message here is that repeatable ESR measurements are indeed difficult, especially so between different instruments, but with patience and good engineering practice can be reeled in to respectable results.

Here's a quick example achieved with various capacitors and LCR Meters TH2830, IM3536 @ 1KHz and Multi-Function Tester T7. Results shown C in uF and (ESR in ohms).

As always YMMV

TH2830                                   IM3536                               T7
43.7068   (0.4911)                   43.7060    (0.49879)            44.78   (0.52)
945.931   (0.03833)                 946.561    (0.03788)            1028    (0.11)
424.159   (0.06465)                 424.435    (0.07221)            440.2   (0.15)
95.6551   (0.04040)                 95.5962    (0.04214)            96.84   (0.11)     Polymer
9.85790   (0.06412)                 9.85680    (0.06405)            9.377   (0.08)     Polypropylene
4.90324* (0.00338)                 4.90205    (0.00813)            4.651   (0.07)     Polypropylene

*Edit, added. Even with careful Setup and Calibrations, Leaded Capacitors with very low ESR (<10 mill-ohms) present a difficult measurement. Here a special fixture which reduces lead and contact effects would be appropriate, similar to what was developed for very Low Z SMD Components.

Corrected

Best,

[KungFuJosh]

TH2830                                   IM3536                               T7
43.7068   (0.04911)                 43.7060    (0.49879)            44.78   (0.52)

Is that line correct? I don't know whether to be more surprised by the disagreement between the 2830 and 3536, or by the (almost) agreement between the 3536 and T7. 😉

[mawyatt]

Good catch, should be 0.4911 

I'll correct it, thanks for pointing this out

My bad

Best,

[KungFuJosh]

Wow, I guess then I'm shocked that the T7 was so close on that one. 😉

[indman]

Here's a quick example achieved with various capacitors and LCR Meters TH2830, IM3536 @ 1KHz and Multi-Function Tester T7. Results shown C in uF and (ESR in ohms).
TH2830                                   IM3536                               T7
945.931   (0.03833)                 946.561    (0.03788)            1028    (0.11)
424.159   (0.06465)                 424.435    (0.07221)            440.2   (0.15)
95.6551   (0.04040)                 95.5962    (0.04214)            96.84   (0.11)     Polymer

Let me ask you - what firmware is installed on your T7 and what controller is it built on?
I see a difference in ESR readings by a factor of almost 2-3 compared to the TH2830 and IM3536.
Look at the measurements I took recently and compare them to your own.
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg5620855/#msg5620855

[Andrey_Ak]

Here's a comparison, the first three devices show correctly.
And the fourth column is the readings of the fake Chinese tester T7 (former TC1).

https://tis.kz/temp/20240908_223153.jpg
https://tis.kz/temp/20240908_223256.jpg

The T7 transistor tester has been producing a fake for a long time, with an incomprehensible controller. It is simply not capable of measuring the ESR, its readings are just an algorithm based on the capacity value.  Perhaps the old first TC1 and T7 testers that were on the original ATMEGA controllers could work correctly, but now they can't be bought, only non-working fakes are on sale. At high ESR values, the readings are no good. Check out the comparison on the links.

[indman]

The T7 transistor tester has been producing a fake for a long time, with an incomprehensible controller. It is simply not capable of measuring the ESR, its readings are just an algorithm based on the capacity value.  Perhaps the old first TC1 and T7 testers that were on the original ATMEGA controllers could work correctly, but now they can't be bought, only non-working fakes are on sale. At high ESR values, the readings are no good. Check out the comparison on the links.

For you and for me, this has been known and understood for a long time. That's why I asked the question mawyatt .
Even though FNIRSI assure you in their letter that their new tester measures ESR correctly, I still doubt it very much, because it is not based on an AVR controller and it is unlikely that Chinese friends have done as much grand work to customize the measurement algorithm as our respected German project authors have done.

[Andrey_Ak]

Well, the M-Tester LCR-T4 and M328 and the like with open firmware measure correctly. 
Well, let's wait for FNIRSI P1 to arrive and test it.

[indman]

It is necessary to compare the results at several frequencies and not just at 1 kHz. The ESR readings on the original AVR Atmega are close to the readings of LCR meters at frequencies of 10 kHz and 100 kHz.
Because I’ll quote from Karl-Heinz’s manual:
"Strictly speaking the ESR of a capacitor depends on the operating frequency and temperature.
Usually the value measured with sine wave-form signal of 100kHz is denoted in the data sheets. This
measurement can not be done with the ATmega without external equipment. With the subsequent
written method the measurement frequency with the standard ADC clock rate will be below 640 Hz
with nearly rectangular signal. With 500kHz ADC clock rate the measurement frequency will be
2400 Hz. To get the value of the equivalent series resistance, the voltage of both connections will
be measured during loading in one direction with the ADC internal reference voltage (1.1V ). After
the measurement the load current will be switched off and the voltage of the capacitor is measured
again without the current."
For the newer ESR measurement method, the manual contains the following note:
"The measurement periode is about 900µs, which results
to a frequency of about 1.1kHz. Because the load pulse is very short, the measurement result is
comparable to measurements with 10kHz"

[indman]

Well, let's wait for FNIRSI P1 to arrive and test it.

I have not yet seen full testing of this tester, but this message already allows us to slightly assess the reliability of the ESR readings.
https://www.eevblog.com/forum/testgear/smart-smd-tester-ms8911/msg5632465/#msg5632465
ESR of 50 mOhm for the Nichicon RNS1C470MDS1 capacitor - such a capacitor can safely be sent to the trash bin, if you believe this tester. 
The Fnirsi LCR-ST1 tweezers give more realistic readings for this capacitor at a frequency of 10kHz - 17mOhm
There are fairly high-quality photographs of the hardware components of this toy and a short review here
https://mysku.club/blog/aliexpress/101064.html
I especially laughed at the 22 Ohm Rds of the N-E mosfet.

[mawyatt]

Here's a quick example achieved with various capacitors and LCR Meters TH2830, IM3536 @ 1KHz and Multi-Function Tester T7. Results shown C in uF and (ESR in ohms).
TH2830                                   IM3536                               T7
945.931   (0.03833)                 946.561    (0.03788)            1028    (0.11)
424.159   (0.06465)                 424.435    (0.07221)            440.2   (0.15)
95.6551   (0.04040)                 95.5962    (0.04214)            96.84   (0.11)     Polymer

Let me ask you - what firmware is installed on your T7 and what controller is it built on?
I see a difference in ESR readings by a factor of almost 2-3 compared to the TH2830 and IM3536.
Look at the measurements I took recently and compare them to your own.
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg5620855/#msg5620855

We've had the T7 for some time now and haven't ever updated the firmware, it's in original state. T7 is based around an Atmel ATMEGA324PA U-TH 35455G 1950E7D.

This T7 apparently does not use an algorithm for ESR, we proved to ourselves by measuring a ~47uF Electrolytic with 0.42 ohm ESR. Measured 1 ohm resistor (~1.1 ohms),  then added in series with cap and T7 measured 47uF with 1.5 ohm ESR.

BTW this is a simple way to verify if ESR is reasonable and measured properly, or at all. Just add a known small value series Resistor with the DUT cap and see how the ESR reading behaves. Of course do this at a low enough frequency where DUT and Resistor lead inductance doesn't matter!!

Anyway, for us the T7 does its intended purpose, and that is identifying a component with approximate values/types/polarities and NOT for any type precision or detailed comparison measurements, we have multiple precision lab instruments for this

As always, YMMV

Best,

[indman]

We've had the T7 for some time now and haven't ever updated the firmware, it's in original state. T7 is based around an Atmel ATMEGA324PA U-TH 35455G 1950E7D. This T7 apparently does not use an algorithm for ESR, we proved to ourselves by measuring a ~47uF Electrolytic with 0.42 ohm ESR.

You still have a classic T7 clone on a proper Atmega. If you install OSHW firmware and calibrate it properly, it will measure ESR almost similar to your LCR meters TH2830 and IM3536. This has been proven time and time again by numerous users of similar T7's to yours. But it already depends only on your desire. If you are happy with the Chinese firmware, then so be it

[mawyatt]

You still have a classic T7 clone on a proper Atmega. If you install OSHW firmware and calibrate it properly, it will measure ESR almost similar to your LCR meters TH2830 and IM3536. This has been proven time and time again by numerous users of similar T7's to yours. But it already depends only on your desire. If you are happy with the Chinese firmware, then so be it

Please provide a link to this resource.

Best,

[indman]

Please provide a link to this resource.

Ok!
The current k-firmware distribution is here:
https://github.com/kubi48/TransistorTester-source/tree/master/trunk
There is a folder for your clone "mega644_T7_Mod". It does not contain the firmware for your ATmega324, but it is not difficult to compile it if you so desire.
The current m-firmware distribution is here
https://github.com/madires/Transistortester-Warehouse/tree/master/Firmware/m-firmware
It does not contain ready-made firmware for your clone, but it is also not difficult to compile.

But I must give you one important warning so that you do not later blame me for breaking your clone.
In order for the OSHW firmware to work normally on your T7, you will have to work a little, that is, program another small chip for 8 legs or replace it with a simple circuit of 2 transistors to control the clone’s power.

[indman]

BTW this is a simple way to verify if ESR is reasonable and measured properly, or at all. Just add a known small value series Resistor with the DUT cap and see how the ESR reading behaves. Of course do this at a low enough frequency where DUT and Resistor lead inductance doesn't matter!!

A long time ago I did the same experiment with an additional no-inductance resistor 17,4 ohm when I checked how my multifunctional Chinese device BR866A measured ESR and C. I even saved the photos, see below 

[KungFuJosh]

I'm sure we'll all be shocked to see that the P1 still cannot accurately test ESR. The P1 doesn't have open or short correction either. It comes with the 3 shitty test clips like the DSO-TC3, but neither the manual nor the device itself show any way to apply any kind of correction.

[BillyO]

It comes with the 3 shitty test clips like the DSO-TC3

But it does come with an interchangeable test fixture so that you can design and build whatever it is you want for your purposes.

Mine has arrived and I'll be playing with it today.  I'll let y'all know.

BTW, what is the ESR of that cap according to the Hioki?

[KungFuJosh]

It comes with the 3 shitty test clips like the DSO-TC3

But it does come with an interchangeable test fixture so that you can design and build whatever it is you want for your purposes.

Mine has arrived and I'll be playing with it today.  I'll let y'all know.

Yes, that is cool. It has that cute SMT test fixture too, despite not having anything to press the SMT device securely on the pads.

But, I still wouldn't use it for anything besides transistor testing...which I will test out later.

[BillyO]

You may not see my edit above, so - I'll ask again .. what does the Hioki say tha ESR of that cap is?  Just for interest sake.

[KungFuJosh]

You may not see my edit above, so - I'll ask again .. what does the Hioki say tha ESR of that cap is?  Just for interest sake.

lol, nope. Didn't see it.

It's the same cap as 1 of the 3 tested here: https://www.eevblog.com/forum/testgear/fnirsi-lcr-p1-%2430-lcr-tester-(august-2024)/msg5635251/#msg5635251

Claimed 21mΩ ESR, tested around 26mΩ.

[KungFuJosh]

Same transistor, repeated results for each device. Which one is the (bigger) piece of shit?

[indman]

Same transistor, repeated results for each device. Which one is the (bigger) piece of shit?

Apparently the one that is larger in your photo. But the boxes are beautiful for $30

[BillyO]

Okay,

Had a chance to play around with the LCR-P1.

Generally, it's as good or better at testing most components as are the GM328, T4 and T7 I have.  For testing capacitance, it gets the value of the capacitor sufficiently well for a sub $30 device.  However, like most of these cheap testers, you cannot get a reliable ESR reading out of it.

As  KungFuJosh said, there is no calibration procedure.  They must calibrate it at the factory.  Maybe if we badger them enough they could include that feature in a future firmware.  That said it was as accurate or better than the 3 other units I have, even after calibrating them.  Its overall functionality is not a deep as that of the GM328, but I find a lot of that is a waste of time.  YMMV

On the other hand, the build quality and the removeable test fixture are winners in my book.  Also very nice are the ability to test Zeners up to 32V and the ability to do butt simple firmware updates via USB directly.

Overall I rate it as a definite contender in this market.

I attached a spreadsheet of an analysis of two different 100uF capacitors, one a low ESR unit and the other a cheap little Chinese device.  I don't have the actual specs for these caps, but that was not the point.  The point was to see whether the 4 component testers could agree on what they measured (they did on capacitance value, they did not on ESR) between each other, a XJW01 (which is not awful) and using a scope and generator (the most accurate way available to me).

Here is a link to the latest firmware (1.0.5) in ZIP format: https://drive.google.com/file/d/1-yvSpG4YlS5MrrkAAr7HIxCWWDscbC7t/view?usp=sharing

[BillyO]

Same transistor, repeated results for each device. Which one is the (bigger) piece of shit?

What firmware do you have?

I installed 1.0.5 and had no such problems.

[KungFuJosh]

Same transistor, repeated results for each device. Which one is the (bigger) piece of shit?

What firmware do you have?

I installed 1.0.5 and had no such problems.

Same firmware here. I did that before testing anything. It might depend on the transistor, I'll test some others. Either way, that was a fail for the one function I would consider any of these devices for.