$20 LCR ESR Transistor checker project

[hapless]

V_LCD together with temperature compensation can be used for contrast control, but it is possible to fry the LCD that way. But, for as long as you can determine the safety limits, I don't see why it shouldn't be an option.

[madires]

I've just released 1.29m:
- Added touch screen support and driver for ADS7843 compatible touch controllers.
- Fixed bug in contrast setting for PCD8544.
- Fixed silly error in CheckSum().
- Driver for ST7920 based LCD modules with 64x128 pixels.
- Optimized SmallResistor() and changed detecton logic in CheckResistor() to cope better with low value resistances and possible probe contact issues.
- Changed control logic and treshold for Darlington BJTs in Get_hFE_C() to fix issue with some NPN types.
- Global driver for SPI bus. Modified display drivers and configuration accordingly.
- Italian text provided by Gino_09@EEVblog.
- Support for HD44780 with Cyrillic font by hapless@EEVblog.

Touch screen support is meant primarily for ATmega 644/1284 because of the additional IO pins. The display has invisible touch bars at the left, right, top and bottom. The left and top bars act like a rotary encoder being turned anti-clockwise, while right and bottom bars act like a clockwise turn. They also got a speed-up functionality when touched for more than 300ms. The display's center area does the same as the test push button, but it's just a software version (won't power the Zener diode check for example). Of course there's also an adjustment for the touch screen.

A lot of effort went into this new firmware version for moving the SPI communication from the display drivers into a common SPI framework. That was necessary for driving additional SPI clients, and I also had to introduce new configuration options. I've tried to keep the changes simple (added them as aliases in case of bitbang SPI) and hope they'll work for you.

[pepe10000]

Thanks Madires.

Measurement of low-value resistors (less than 1 Ohm) has improved greatly.

It no longer marks a few picofaradios, marks the correct resistance.

I am attaching photos of the LCR-T4-H and the AY-AT Diy Kit.

A greeting.

[perieanuo]

hello everybody,
I just realised something is terrible wrong with my AY-AT compiling :
-so I have just compiled several times 1.29 for AY-AT (7735 LCD) with encoder on PD1/PD3 and I can't just get him measure capacitors.It shows almost double value.
everytime I put inside 1.25 version from trendy it starts measuring correctly,tried with 10 capas (pf,nf,uF).

besides that,the 1,2 and 3 inputs measure almost perfect resistances and identifies transistors.

calibration gives always error!

what i'm doing wrong in your oppinion?
here's the stuff,can anybody test/confirm my fw on ay-at board?

[madires]

Maybe a 16 MHz crystal but firmware compiled for 8 MHz?

[casinada]

Excellent Job 
Color AY-AT 16MHz

[perieanuo]

hello,
you're a genius thanks I made a stupid beginner's mistake.

 you made my day,

best regards, pierre

ps: still have some discrepancies for small capas like those 22 pF for quartz,shows 55-56 avec 1.29 and 26pF avec 1.25m

[madires]

Have you done the adjustment (measure a 220nF - 2.2µF film cap 3 times and then run the self-adjustment via the main menu)? 

[perieanuo]

hi,
did the thing, now pF range seems fine,22pF shows 22 pF !!!
i didn't know that I need to measure something before,I always did calibration after fw upgrade ana cycle power off/on
resistors seems fine too,I checked some 5-6 pieces all around

thanks

[jorgemiguel4]

Hello, I have the TC-1 v2.12k, color TFT version. After a few minutes of using it went dead, opened it and found some bad solder joints in the LCD connection. It's working fine again, except the inductor test that shows wrong DC resistance. 7mH and 150Ohm with a inductor that reads less than 1Ohm in my multimeter. With simple resistors it works fine. Is there anything I can do?

[jakeisprobably]

Hello all
  I've been working on the latest clone version of the transistor tester project. My PCB is K103603BS and it uses the ST7735 version of the graphic display. I apologize for the crude looking schematic. I wanted to try my hand at drafting the schematic by hand and just went with it at least for now.
   I've been posting a few amateur things on YT and started this little project of sorting out the difference between this clone and the original project schematic. There are a few corrections made to the version I added here versus the first draft from the YouTube post I made. There are probably a few more errors other smarter people will catch as well. I apologize in advance for any errors I have made. Hopefully someone finds this information useful.
https://youtu.be/T8Fl7HL0c0c

https://drive.google.com/file/d/0Bx7o06dJNau1bzlzOXJhSWFjalk/view?usp=drivesdk
https://drive.google.com/file/d/0Bx7o06dJNau1M0RId2FYTXp4Tk0/view?usp=drivesdk
https://drive.google.com/file/d/0Bx7o06dJNau1OW5CVi1seTVhZnM/view?usp=drivesdk

[amspire]

I did post some PDFs for this board:

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg1215425/#msg1215425

The schematic I posted is not perfect - they got the TL431 connections wrong for a start.

[jakeisprobably]

Thanks for that. I am using the original parts designators from the official schematic, with a couple of exceptions namely where I placed C3, and I reused C10 as it is not used on this board.  These designators should maintain any relevant reference information from the official documentation... At least that is my goal. I apologize for missing the previous post. I've read bits and pieces of this thread but 149 pages takes time and a few sessions for me to complete.

[perieanuo]

hi everyone,
I'm working on some COMPLETE and CORRECT (and annotated also) schematic in eagle for the ay-at clone with 7735 graphic display for the members,in order to track the repairings and to setup easily the compiling part.
I'll post soon and dont't shoot me for mistakes,let's put the thing up to date.
and why not add the rest like zener...,change eventually the uP,add tactile,and put up an order for pcb-s

best regards,
pierre

[madires]

   I've been posting a few amateur things on YT and started this little project of sorting out the difference between this clone and the original project schematic. There are a few corrections made to the version I added here versus the first draft from the YouTube post I made. There are probably a few more errors other smarter people will catch as well. I apologize in advance for any errors I have made. Hopefully someone finds this information useful.

Nice video! And don't forget the m-firmware

[madires]

Hello, I have the TC-1 v2.12k, color TFT version. After a few minutes of using it went dead, opened it and found some bad solder joints in the LCD connection. It's working fine again, except the inductor test that shows wrong DC resistance. 7mH and 150Ohm with a inductor that reads less than 1Ohm in my multimeter. With simple resistors it works fine. Is there anything I can do?

The resistance measurement is the same for resistors and inductors. Have you checked other inductors too?

[jorgemiguel4]

Hello, I have the TC-1 v2.12k, color TFT version. After a few minutes of using it went dead, opened it and found some bad solder joints in the LCD connection. It's working fine again, except the inductor test that shows wrong DC resistance. 7mH and 150Ohm with a inductor that reads less than 1Ohm in my multimeter. With simple resistors it works fine. Is there anything I can do?

The resistance measurement is the same for resistors and inductors. Have you checked other inductors too?

Yes, I have tried with two similar ones with similar results. The last one read 6.36mH and 148 Ohm while in my multimeter it reads 0.63 Ohm.  Don't know if it matters but both inductors are common mode chokes.

[perieanuo]

here's the 1st version done with eagle 8.2.2,it's not perfect but quick reference for setup LCD ports, can help
revised TL431 drawing ans proposed LM4040 precision reference, ISP 6 pins header (in fact I have DB9 but it's ugly but simple to implement and good fiability)
eliminated socket and added pads to connect with female bananas on enclosure
SVR05-4 description is not correct,i'll remake the library part or search for a good one


best regards,
pierre

[madires]

Yes, I have tried with two similar ones with similar results. The last one read 6.36mH and 148 Ohm while in my multimeter it reads 0.63 Ohm.  Don't know if it matters but both inductors are common mode chokes.

That's strange! I've checked a 2.7mH and 22mH common mode choke with the m-firmware an an older k-firmware. The measured values are reasonable.

[jakeisprobably]

here's the 1st version done with eagle 8.2.2,it's not perfect but quick reference for setup LCD ports, can help
revised TL431 drawing ans proposed LM4040 precision reference, ISP 6 pins header (in fact I have DB9 but it's ugly but simple to implement and good fiability)
eliminated socket and added pads to connect with female bananas on enclosure
SVR05-4 description is not correct,i'll remake the library part or search for a good one

best regards,
pierre

  I will have to take down my filming setup to get to my desktop and check this out. Alternatively someone could greatly help me out by posting an image. I'd like to integrate or work with you to add this into my current project.
   I am partially disabled, and do all my filming editing and illustrations from an old Samsung Galaxy phone. I am limited to sitting or standing for 1-3 sporadic hours total throughout the day on my good days. This means I'm super slow to complete projects but I can devote a massive amount of time to research editing and creating illustrations.
   I am using the Sketch mobile app (like Microsoft Paint with more layering options) to map out the traces and edit the schematic. I still have and can modify these files easily. I uploaded them to the YT video as streamlined as I could so anyone can visually check my work. I didn't initially plan to add them but it seems like a good resource for all. The only file I can't edit easily is the picture of the PCB with the parts designators. I can remake it if need be but I mistakenly deleted the file this came from while managing my limited storage space.
   I plan to add test points by demonstrating where to bend pins to allow easy test point connections. I also plan to show how to add the ISP header connections. I also want to add pin 1 of the TVS IC to either the Frequency measurement or Voltmeter circuit. The last PCB modification I plan to use on the first stage of this build is to add a trimmer capacitor to replace one of the 22pF caps at the crystal.
  The project will get integrated into an old upcycled enclosure from a HP printer power supply brick. These are easy to pry open with channel locks, and they fit the PCB perfectly while leaving plenty of room for a small transformer and battery.
  If I can figure out the programming side of this device (total ISP noob), I want to add the zener threshold tester, but I plan to use a MC34063 if I go that route.
   ...And if everything goes really well I'd like to look into adding a INA106 differential amplifier with a laser trimmed gain of 10. I was planning to build the milliohm meter from the Scullcom Hobby Electronics YouTube channel, but I think the diff amp might be more useful when integrated into this project. I would probably need help understanding the programming aspects involved to make this happen, but I think this little mod could be interesting.
   The last thing I've been looking into is why "discharged capacitors" are mentioned, but only 'before the device is powered on.' I assume this is due to the TVS IC's need for power. If that's the case, why not simply add a 2 pole normally closed relay to short all 3 test leads with a short on delay circuit powered from the collector of the PNP transistor? Seems like that would solve the problem of mega-burns, but I've not done my research in this area yet.

  The images for Power and Ground test points 1-9 to show in my next YT upload are attached.

 Let me know what you think or if you think I should go in a different direction.
  Thanks, -Jake.

[jakeisprobably]

Nice video! And don't forget the m-firmware

Thanks for everything Markus. I started reading from the beginning of this thread today trying to read everything you guys have been doing here and elsewhere... WOW!! just wow.
   This thread is much more relevant than I had assumed after seeing bits and pieces other people had linked to.(... and then feeling overwhelmed by the size of this.)
  I tried taking my usual screenshot notes as I read through... I haven't even made it to double digits and already I need to create folders for organizing the range of subjects covered and details I haven't seen elsewhere. This thread needs a wiki or something. I may try to distil my notes from this thread for others at some point.... Although I get the feeling everything I'm saying has been said and done in this thread before
  Thanks again, -Jake.

[upsss]

Hi,

ps hello,
I posted attached first revised schematics for AY-AT clone with 7735 graphical display with some useful annotations
regards,pierre

A quick observation of your schematic, your rotary encoder and its pull-up resistors are drawn wrong.  You are missing the ground connection on the encoder and both sides of it including the pull-ups are shorted.  You should not have lines going through a component like on R7, 8, 9, 10, 13, 15.  Also all junction connections (dots) should be at the actual junction and not somewhere along the line.

[perieanuo]

Hi,

ps hello,
I posted attached first revised schematics for AY-AT clone with 7735 graphical display with some useful annotations
regards,pierre

A quick observation of your schematic, your rotary encoder and its pull-up resistors are drawn wrong.  You are missing the ground connection on the encoder and both sides of it including the pull-ups are shorted.  You should not have lines going through a component like on R7, 8, 9, 10, 13, 15.  Also all junction connections (dots) should be at the actual junction and not somewhere along the line.

I corrected encoder ground.also he had a green line in schematic that wasn't a wire but apear like one,modified also.redrawed resistors,but that's just aestethics.
pullups for encoder were correct.
thanks for remarks,pierre

[upsss]

The pull-ups do go to the 5v but their other end you have them shorted, R5-R6 are not supposed to be in parallel!  As far as the dots junction, it is not a mistake it is just not a proper way of drawing a schematic.

[bianchifan]

hi everyone,
I'm working on some COMPLETE and CORRECT (and annotated also) schematic in eagle for the ay-at clone

Transistor tester's firmwares are Open Source, original PCB designs/layouts wre Open Hardware!
Why the hell most poeple like to use shittin' closed source programs even in OPEN projects ??
There are OPEN SOURCE variants , too!
Some people like GEDA (Linux), some people like KICAD.
Nowadays KICAD should be first choice..

This thread needs a wiki or something.

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