$20 LCR ESR Transistor checker project

[indman]

Some updates. 150mH work fine (around 12kHz), and lower limits of 1nH and 10fF seem to be reasonable.

Madires, i don't really need a 10fF measurement, but I am very interested in stable results when measuring 1-10nH.

[Szybkijanek]

stable results when measuring 1-10nH

I do not think that it would work on this tester because for such a resolution you need high accuracy and physically the equipment does not allow it.

[indman]

I do not think that it would work on this tester because for such a resolution you need high accuracy and physically the equipment does not allow it.

This is very possible without the use of expensive equipment! But on condition that not cables for connection are used, but fixed measuring contacts. Check out these links. The usual standart arduino is used.
https://soldernerd.com/2014/12/14/arduino-based-inductance-meter/
https://soldernerd.com/2017/01/29/standalone-inductance-meter-on-a-etched-board/
These schemes can be further simplified, as done on the Russian-language forum VRTP.ru. But this is already a separate topic for discussion.

[Szybkijanek]

Hmm, not bad, so we need at least 1MHz frequency for measurement 1nH inductor according to the table below:
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[madires]

1 MHz could be possible. The self-adjustment checks the base frequency of the LC tank (just L_i and C_i) and also the frequency with the reference cap C_p connected. I'll use constants you can easily change if you like to use other values for L_i and C_i to increase the base frequency. The math is explained in the source. So you just have to calculate the two frequencies and update the constants for the limits.

[madires]

Maybe you've already seen one of the cheap PIC LC meters which are based on a simple LC oscillator circuit. I've started to work on implementing the same measurement method with the LC oscillator as a hardware option. It's meant as option for ATmega644/1284 based testers. If you like to build one please find the schematic attached

I've messed up C3 and C4, so here's the updated version:

[madires]

Happy holidays!

v1.42m
- Updated 6x8 fonts (thanks to Bohu).
- New ISO8859-2 based 6x8 font (FONT_6X8_ISO8859_2_HF, thanks to Bohu).
- Added LC meter hardware option (HW_LC_METER). It's based on a simple LC oscillator circuit, similar to some inexpensive LC meter kits.
- Changed Display_Value() to support also fempto (f).
- When CYCLE_MAX is set to 255 the automatic power-off is disabled and the tester keeps running until it's powered off manually.
- Fixed issue with display of strange frequencies in the extended frequency counter in a specific situation (reported by zybkijanek@EEVblog). Also changed display output of a missing signal or a too low frequency from '0Hz' to '-'.
- The basic counter displays now a '-' instead of '0Hz' in case of a missing signal or a too low frequency.
- Added option to display I_C/I_E test current for hFE measurement (SW_HFE_CURRENT, suggested by Obelix2007@EEVblog). Also added corresponding remote control commands (I_C and I_E).
- Added Romanian texts (thanks to Dumidan@EEVblog).
- Added configuration switch for ESR tool (SW_ESR_TOOL, suggested by indman@EEVblog).
- Changed text output of E series norm values to also display unit (suggested by indman@EEVblog).
- Updated alternative Polish texts (thanks to Jacon@EEVblog).
- Last text line on display was simply overwritten when UI_KEY_HINTS is enabled (reported by Obelix2007@EEVblog). Added function to wait for user feedback before clearing last line.
- Updated Spanish texts (thanks to pepe10000@EEVblog).
- Corrected error in "#define" for E96 norm values (reported by Obelix2007@EEVblog).
- Added driver for ILI9488 based displays (8/16 bit parallel and 4-line SPI, thanks to Bohu for a sample display).

Please download at https://github.com/madires/Transistortester-Warehouse or https://www.mikrocontroller.net/svnbrowser/transistortester/.

[indman]

Hi Madires! Thank you for great work and another gift for the New Year and Christmas!

I have a question on the README documentation:
"The PIC LC meters usually have measurement ranges of 10nH to 100mH, and 0.1pF
to 900nF. They seem to use a gate time of 100ms for the frequency counter.
The m-firmwmare uses auto-ranging with gate times of 100ms and 1000ms to
improve the resolution for low value L/Cs. Thus the ranges start at about 1nH
and 10fF. The maximum inductance supported is roughly 150nH. Regarding
capacitance I've run into an issue with my PCB. At around 33nF the output
signal starts having some spurs in the rising and falling edges causing the
frequency counter to see more pulses than there really are. Could be a problem
with my PCB layout. Despite that, the maximum should be around 900nF (beyond
that the LC oscillator will become unstabe). "

Is everything correct with the maximum inductance and capacitance values? 150nH or 150mH? 900nF?
Perhaps a faster and more modern comparator could be tried in the LC meter design instead of the outdated LM311?

[pepe10000]

Hello Madires, thanks for the new firmware, I am attaching the new Spanish language file with the latest improvements that you have added.

A greeting.

[madires]

Is everything correct with the maximum inductance and capacitance values? 150nH or 150mH? 900nF?
Perhaps a faster and more modern comparator could be tried in the LC meter design instead of the outdated LM311?

The maximum for inductance is around 150mH. "nH" is a typo. And the maximum for capacitance is around 900nF as long as the LC oscillator has a clean output signal. A larger capacitance causes the LC oscillator to stop. Modern comparators should work fine too. I was simply too lazy and used the well known circuit.

[indman]

And the maximum for capacitance is around 900nF as long as the LC oscillator has a clean output signal. A larger capacitance causes the LC oscillator to stop.

Madires, it is a known issue for LM311 based generators. Take a close look at the LC / ESR meter schematic I made a few years ago. Pay attention to the resistor R17, the role of this resistor is to remove parasitic surges at the signal edges, which appear just at low oscillation frequencies. This allows (in addition to the chain) to increase the upper limit of measurements by about 5 ... 6 times. Also look closely at the feedback loop of elements C19-R16-L3. My upper limit of measurements of non-electrolytic capacitors reached 50μF. I have attached a photo below.

[Jacon]

Hi Madires,

Thank you for such nice Christmas gift 
Enclosed please find updated Polish language translation file.

Greetings

[Electro Fan]

Sorry for being out of sync in the Q&A but does anyone have a link to a good eBay seller with a recommended modified k-version with the fancy GUI?

[indman]

Electro Fan
What do you mean by a fancy GUI? Do you need a multifunctional tester with working options or a beautiful interface?
Give an example of an upgraded k-firmware?

[Electro Fan]

Electro Fan
What do you mean by a fancy GUI? Do you need a multifunctional tester with working options or a beautiful interface?
Give an example of an upgraded k-firmware?

Hi indman,

Thanks for your reply.  And thanks for all your good leadership on the LCR ESR Transistor checker project.

I’ve been following this thread for a long time and recently thought it might be time to see if there is some consensus on “a” or “the” preferred tester.  Rather than reading all 250 plus pages I decided to read from the end to see if I could find some recent consensus.  (After 7 years of this thread I’m guessing the answer is “it depends”, and that the testers keep evolving.)

My sense is that different users want different testers for different purposes, of course.  Some might want an inexpensive versatile tester to get good enough measurements for various tests on various devices.  Others might want a tester that is somewhat open source / modifiable to meet particular requirements or because they enjoy modifying test equipment.  Others, like myself, might be interested primarily in the educational opportunities this class of testers (and test equipment) in general can provide.

In any event, on page 265 I saw a reply from madires to an inquiry by eti regarding the particular firmware on a particular device (I think a LCR-T4) in which madires said “That's a modified k-firmware with a fancy GUI.” – so I figured those might be somewhat definitive terms, but maybe they haven’t been officially confirmed terms.   In any event, armed with a descriptor of something that looked interesting I worked my way further back in the thread and was happy to find on page 261 a link to your good pdf summary.  Nice work, thanks!

With these good breadcrumbs I then shelled out to eBay and found a bunch of alternatives including some GM328, GM328A, GM238A+, and LCR-T4.  I’m not wedded to these models, whatever model make sense is cool.  These are just some examples, they are nearly dart throws that happened to land somewhere in the vicinity of the target.

What I’m looking for is a device that tests a wide range of components (don’t even really care which exactly because at the prevailing prices if necessary 2 or 3 might fit in the budget).  The main objective is to find one or more testers that provide a UI with schematic-like symbology to help tie the measured values to the internal circuitry and performance attributes of the DUT.

While it would be great to find a tester that does “everything” (measures many values for many devices) and that has highly accurate test results those are not my primary objectives.  (Not to mention "does everything" and "with high accuracy" don't seem like reasonable asks for a $20 tester.)  My preferred tester is a tester that will provide useful educational feedback about at least some popular devices (transistors, inductors, capacitors, resistors, etc.) and that helps tie the measured values to the particular device leads (especially for various types of transistors, of course).  I have a couple Peak Atlas products and I find the symbolic plus measured value display, and the physical to logical (socket/lead) ties in their UIs to be helpful when studying (or trying to teach) the characteristics of DUTs.

Of course it would be nice if the tester had a decent case to hold the battery and DUT in place and knobs and buttons that fit human fingers, etc. but my primary interest is a highly informative user interface, especially the display.  If there is such a device that comes to mind and it has the good house keeping seal of approval of the users in this thread that would be ideal as having access to the users here is almost as valuable (or more valuable) as the device itself.

Thanks in advance for any particular product recommendations or any other guidance.

[indman]

In any event, on page 265 I saw a reply from madires to an inquiry by eti regarding the particular firmware on a particular device (I think a LCR-T4) in which madires said “That's a modified k-firmware with a fancy GUI.” – so I figured those might be somewhat definitive terms, but maybe they haven’t been officially confirmed terms.   In any event, armed with a descriptor of something that looked interesting I worked my way further back in the thread and was happy to find on page 261 a link to your good pdf summary.  Nice work, thanks!

Chinese friends have been selling the LCR-T4 tester with modified firmware for more than 5 years and it remains the most popular and affordable device today.
And many of its owners are still sure that it was invented and developed by Chinese engineers, and that everything that was released later was LCR-T4 clones! 
But, those who have been familiar with the topic for a long time, knows perfectly well who is actually the author of this wonderful project and makes a huge contribution to its further development.
I believe that despite a very rich selection of different clones, the most convenient and informative in every sense is a device that you make with your own hands and mind.
Trust me, it will bring you much more knowledge, benefit and good mood than the purchased device.

[Electro Fan]

So setting aside the build vs buy already made for the moment, is the LCR-T4 your top recommendation?  Or is there another model you prefer?  Thx

[indman]

etc. but my primary interest is a highly informative user interface, especially the display.  If there is such a device that comes to mind and it has the good house keeping seal of approval of the users in this thread that would be ideal as having access to the users here is almost as valuable (or more valuable) as the device itself.

If so, the LCR-T4 is almost perfect for your interests.

[timelessbeing]

I bought the m328 kit because it's easier to mod (no SMT), socketed mcu , included rotary enc, and because it's a kit I can throw away the sh***y components right off the bat.

[Electro Fan]

I also prefer socketed vs SMD.

I’m sure it’s in here somewhere but what are the key distinctions between the m328 and LCR-T4?  Thx

[Electro Fan]

There's a common misunderstanding about the Transistortester being an LCR meter. It isn't, but it can measure L, C and R within some limits, and the k-firmware's SamplingADC function allows to measure also low value L/Cs. Inexpensive LC meters like the LC-100A are basically a simple LC oscillator plus a frequency counter. The Transistortester is presumably a little bit more accurate for capacitors above 1µF. Proper LCR meters, for example DER-EE DE-5000, apply an AC signal and measure voltage and current.

The AY-AT/GM328A is a nice general purpose Transistortester clone. However, I'd recommend to get a proper LCR meter if the LC-100A doesn't work for you.

I’m obviously jumping around in this thread trying to get up to speed on the basics of the thread but just wanted to say this is very helpful:

There's a common misunderstanding about the Transistortester being an LCR meter. It isn't, but it can measure L, C and R within some limits, and the k-firmware's SamplingADC function allows to measure also low value L/Cs. Inexpensive LC meters like the LC-100A are basically a simple LC oscillator plus a frequency counter. The Transistortester is presumably a little bit more accurate for capacitors above 1µF. Proper LCR meters, for example DER-EE DE-5000, apply an AC signal and measure voltage and current.

Thx

PS, if this thread had it’s own sticky this would be a good sticky

[timelessbeing]

See indman's post from Oct 8 for a PDF comparison of clones

[Ser9ei]

Hello!
where can i find a sample (photo) of implemented devices (testers) with the new "hardware lc-meter" feature from the latest firmware 1.42m?
Thanks a lot and sorry if it was already here, but i am a new member of this forume, and here are a lot of pages on this thread)

[madires]

Welcome to the forum! There aren't any testers yet which come with the LC oscillator circuit, but you can build the oscillator on a piece of perfboard. And also have a look at the changes suggested by indman a few posts back.

[brunosso]

How to set the makefile for the MK-328 tester? This tester is in the Clone PDF but not in the Clones setting file