$20 LCR ESR Transistor checker project

[madires]

I recently bought a TC2 HaoQi from AliExpress and the PCB was silkscreened with "T7-PLUS V2.0". The tester is utter crap as the measurements are very inconsistent, erroneous and all over the place 

Could be one with an alternative MCU. A few pages back I posted some hints about detecting those (or see top of the Clones file in the source archive).

[Calambres]

The MCU is a no-brand-no markings variant. I'll take some photos and will post them here...

[LeWidget]

Still looking to get one of these testers. Are there any versions &/or sources that are good & accurate straight out of the box or do all need some sort of modding?

[maxmatteo]

i went with the Bside Esr02 pro, has a real atmel inside and works great...

[Calambres]

i went with the Bside Esr02 pro, has a real atmel inside and works great...

Where did you buy it?

[maxmatteo]

aliexpress

[Pygmalion]

Hello!  I am late to the party, so I hope you won't mind.

I want to have LCR ESR tester of my own and I just don't want to buy a fake one.  On the other hand, I have substantial experience with Arduino and even created my own projects with SMD ATmega328, with PCB designed in KiCAD and ordered at JCLPCB.

Would you recommend me making my own?
Which DIY project / ATmega328 sketch would you recommend?
Is the sketch for LCR ESR testers still being actively updated and is the latest code better than the one used in Chinese clones?

[madires]

Yes! The best Transistortester is the one you make yourself. Please see https://github.com/madires/Transistortester-Warehouse/tree/master/Hardware for a starting point. There are two OSHW firmwares (k and m). You will find the m-firmware in the same repo and the latest k-firmware at https://github.com/kubi48/TransistorTester-source. Most clones are based on the k-firmware. Both OSHW firmwares are way better in functionality, but have less fancy graphics.

[Pygmalion]

Explanation of difference between m and k firmware is supposed to be in your README file, which I cannot find...  Can you help me with this?

I am absolutely interested in making my own, because I want to have the latest firmware all the time.  Is building one yourself much more expensive that buying a good quality finished Chinese clone?

[madires]

The README file is part of the m-firmware's source archive. For the list of differences look for section "What's different?" (around line 157). Building your own tester is probably a bit more expensive (it's mainly the ATmega, display and PCB). But you'll get a genuine ATmega and all the hardware options you want to have.

[Pygmalion]

I just realised that I can also make a stripboard version . In this case, I already have most of the components on hand (DIP ATmega and 16x2 display included).  But I did not find a nice KiCAD design. I might be tempted to make my own if there is none available.

BTW, in my experience the most expensive part in my projects is shipping from JLCPCB ... everything else can be sourced locally or at AliExpress for a negligible shipping.

I also discovered that you guys use diylc, a great free alternative for Fritzing program, which is no longer free . I have always drawn my stripboard projects in LateX/TikZ .

Even after reading the FAQ, the content of github is still confusing. There are 14 files in the hardware folder and you can not tell what each file is about unless you open it (and sometimes you do not know even after you open it ).

I would assume that all hardware projects can use both firmwares, right? On the other hand, the FAQ mentions using a different, more powerful chip than the ATmega328. I only have ATmega328s at home (both DIP and SMD), but I would be willing to buy another chip if it would improve functionality. I am a bit confused on this point.

[indman]

On the other hand, the FAQ mentions using a different, more powerful chip than the ATmega382.

Not ATMega 382 but ATMega328
Read the user manual again carefully and you will find a list of supported controllers as well as answers to almost all future questions.

[Pygmalion]

Not ATMega 382 but ATMega328

Corrected.  By the way, "m" is lower case 

Read the user manual again carefully and you will find a list of supported controllers.

That is not the point. The point is that using another controller with more than 32kB of memory makes sense only if there is firmware that utilises that extra memory. If there isn't any, even just in plan, it does not make sense to use anything more advanced than the ATmega328.

[indman]

That is not the point.

This is precisely the point. If you are going to build your own device, then you will have to master the compilation of firmware for it.
If you study the manual more deeply, you will understand that the firmware is compiled for any supported controller, only the set of available plug-in options and settings changes.

[Pygmalion]

That is not the point.

This is precisely the point. If you are going to build your own device, then you will have to master the compilation of firmware for it.
If you study the manual more deeply, you will understand that the firmware is compiled for any supported controller, only the set of available plug-in options and settings changes.

So if I compile with all options then 32k will no longer be enough?

[madires]

I would assume that all hardware projects can use both firmwares, right? On the other hand, the FAQ mentions using a different, more powerful chip than the ATmega328. I only have ATmega328s at home (both DIP and SMD), but I would be willing to buy another chip if it would improve functionality. I am a bit confused on this point.

The basic tester and most options are supported by both OSHW firmwares, a few options only by the m-firmware. Supported MCUs are ATmega328, 324, 644, 1284, 640, 1280 and 2560. The k-firmware supports also older types like the ATmega168.

The point is that using another controller with more than 32kB of memory makes sense only if there is firmware that utilises that extra memory. If there isn't any, even just in plan, it does not make sense to use anything more advanced than the ATmega328.

With multiple additional features enabled the firmware easily exceeds 32kB. So an ATmega644 is the best choice at the moment. Anyway, it depends on which features you need.

[Pygmalion]

OMG. I really appreciate your work, but the learning curve is pretty steep. Someone should create a FAQ for potential builders...

If I understand it correctly, there is no single compile and no single PCB CAD file, because there are zillion different combinations. If they want to build their own device, they have to start from scratch, draw the entire schematic and create the PCB in CAD. And then they might see that their own compile and PCB are later used commercially for Chinese clones...

For me, it's quite doable, but I estimate it would take me (as someone who has neither a job nor formal training in electronics) at least three weeks if I were to focus on just this one project. For one (1) device. I am not sure I want to invest that much time, at least not until I finish my other hobby projects (like overhauling the ZX Spectrum or automating HO switches with DCC...), which will also take months if not years as they are just hobbies. In the meantime, I will just use my DMM and occasionally a signal generator/oscilloscope to measure the more complex things like ESR. Or, more likely, I will just buy a Chinese clone...

PS Can it at least be compiled in the Arduino IDE like the rest of Arduino stuff?

[hapless]

Weeks?! Learning curve? All this simple project requires is a compatible ATMega, a screen and a few resistors to make it work. Great for someone who just learned to solder or for a child. You can throw your first one together on a piece of cardboard within a few minutes. The hardest part is figuring out how to program the MCU, but even that's easy for someone who's got an Arduino, which you clearly do. This is NOT an Arduino project, but it was ported for those who just don't care. Just go to YouTube and watch some videos. People put together these testers with an Arduino and without one within minutes in real time... you can try simply follow what they do. But if you choose to use a standalone MCU it's easier to use the precompiled firmware, which is what you'd probably want to do at first to test things out.

As for an FAQ, there's no need, this project has the best of manuals, find and read it, then RTFM, then consult the manual. It explains everything including how to improve the basic circuit and which displays to use.

And yes, after that you'd probably want to design a variant of your own with a unique PCB created in your choice of software. And take as much time doing it as you need.

[Pygmalion]

I am sorry, I did not make myself clear enough. I could replicate one of those Veroboard projects on github without videos and tutorials in, let's be realistic, a couple of hours. But I just wanted to skip the testing phase and immediately create a "real" device on a "real" PCB and with a 64k IC. Just like these Chinese clones, apart from the 64k IC. And for that I would need the time I specified. So for a "real" device, it's not worth it for me to invest such huge effort to build a slightly better device than the one I can buy ready-made. I am talking about my personal cost-benefit estimate here, which you may not share.  [And since I am afraid the Chinese will send me some rubbish with fake controller, I will end up buying nothing and juggling with my oscilloscope and signal generator forever.  ]

As for the information available, I spent several hours reading documents on github to find out that this is not for me. Maybe I am just stupid or maybe this could all be explained in a few words in a document.  I wanted to make a useful suggestion, but you are absolutely free to ignore it.

[steveharriss]

I have only just come across this project having purchased one of the cheap Chinese clones some time ago. It's been a really useful bit of kit to have around. The fact that so many people have taken the time to share their expertise is brilliant.

I took a look at the DevKit-644 posted on GitHub and decided to have the PCB's made up in order that I can make my own AVR Transistor Tester. They are now on their way to me and I am pulling together the parts that I don't have to hand.

I've seen the advice about matching the resistors and I'll bear that in mind when it comes time to build it. I would like a visual reference though to keep me on track. Is there anyone who has previously built this DevKit-644 who would kindly share a picture of the completed PCB with components. TIA 

[madires]

Please see https://www.eevblog.com/forum/testgear/show-us-your-$20-transistor-tester-enclosures-and-mods/msg1201483/#msg1201483.

[Pygmalion]

I took a look at the DevKit-644 posted on GitHub and decided to have the PCB's made up in order that I can make my own AVR Transistor Tester. They are now on their way to me and I am pulling together the parts that I don't have to hand.

After your post, I went looking for the DevKit-644 project and finally found it in the hardware folder . And after opening it, I found a complete project with KiCAD files. Looks great and may be exactly what I was looking for, especially if I succeed to get it to under 10cmx10cm and half the price of the PCB.

Since this project uses the ATmega644, does this mean that it is the most advanced version of the tester at the moment and that it supports all tester options?

[madires]

Yes and no. That circuit is a basic tester with a few hardware options meant to be used as base for developing and testing new options. If you want to use it as a normal tester please modify the circuit as needed (add a display and more options, remove the relay for the Sampling-ADC's adjustment cap). The main benefits of that ATmega644 tester are more flash, more I/O pins and hardware SPI for driving a display.

[Pygmalion]

Yes and no. That circuit is a basic tester with a few hardware options meant to be used as base for developing and testing new options. If you want to use it as a normal tester please modify the circuit as needed (add a display and more options, remove the relay for the Sampling-ADC's adjustment cap). The main benefits of that ATmega644 tester are more flash, more I/O pins and hardware SPI for driving a display.

​I actually love the fact that the PCB does not include a display . This is a modular approach to the tester, everyone uses the same module PCB and then the display is connected to the module bus; different pins are used depending on the display type.  Also, I have half a dozen displays at home, which I used when researching for my display web page, and I may decide which one to use later .

I see that the PCB already contains a Zener test. Is there a list and circuits for other options?

Also, instead of the near-obsolete 9V batteries, I would prefer to use 5V power and/or Li-Ion batteries with boost-up to 5V, which would also simplify some of the circuitry. (Possibly even using a cheap Chinese boost-up for the Zener part) Is there a reason to use 9V?

That's what's scares me off, designing the optimal circuit... In comparison, PCB design is a piece of cake.

[Obelix2007]

this Tester comes with AtMega324 and I removed it and mount the pincompatible AtMega644.

Sorry for my bad english.

Greeting Horst