AVR Transistor Tester from AliExpress Little t Clone GM328 Basic Circuit Trace
Vložit
- čas přidán 21. 11. 2017
- I personally created this full circuit schematic and show the visual tools I used here. This video covers the graphic monochrome AVR Transistor Tester Chinese Clone that is sometimes called a GM328 or M12864 or Highland. I'm calling it the 'little "t"' because the second t in the name on the PCB is not capitalized. All designators match the official OSHW PDF from Karl-Heinz.
I want to try to make content you and I find useful. This video shows the basic Power and Ground traces quickly. These are the test points you should check after soldering the components, and plugging in the battery, but before testing the device with the microcontroller in place.
I have also included a few images of the totally retraced PCB and matching schematic. Each trace is a slightly different color so a screenshot of both pictures will get you a long way with any difficulties you might experience.
I will try to create another longer video tracing out the entire schematic point to point.
Here is my PDF of this clone version from my GitHub page:
http:github.com/Upcycle-Electronics/AVR-Transistor-Tester/blob/master/TT-Clone-littlet2.pdf
Transistor Tester Project Support Forum Threads
Project Headquarters (Deutsch/English)
www.mikrocontroller.net/topic/...
English/M-Firmware Support
www.eevblog.com/forum/testgear...
Russian
vrtp.ru/index.php?showtopic=16451
Slovak
svetelektro.com/Forum/avr-comp...
--------------------------------------------------
Music by: Martin Gioani
www.martingioani.com
-Yardbird Suite
• Yardbird Suite + Free ...
Creative Commons Attribution License
--------------------------------------------------
Att Clone sellers
亲爱的晶体管测试仪复制品生产商和卖家:
🌟Official Project Webpage
www.mikrocontroller.net/artic...
🌟SVN Repository (all files and software needed for this project)
www.mikrocontroller.net/svnbr...
🌟Deutsch/English Forum
www.mikrocontroller.net/topic...
🌟English Forum/M-Firmware Support
www.eevblog.com/forum/testgear... - Věda a technologie
What would be the best clone version to buy now? Any thoughts? :)
+Mathijs Groothuis
It depends on what you want to do. If you just want basic functionality, go get one of the yellow T3/T4 clones for $6. They are remarkably accurate for a device that uses 5% sense resistors and a 1% voltage reference. You need to be really careful to discharge capacitors before testing, but if you fry the ATmega328 just get a whole new device.
If you really want the most functionality and protection the "AY-AT" (as we call it) has the most features of any kit clone. It is the only version to include the optional circuits for frequency/PWM output//frequency measurement//0.1-50 VDC Voltmeter (which is actually part of the zener threshold test circuit, but it doesn't include the boost converter/voltage generating circuit elements). The AY-AT's have crappy color TFT screens that are not useful and create their own issues with screen refresh rates.
None of the clones come with a 16mhz crystal. They all come with an 8 mhz crystal, and 1% resistors. They don't come with a functional ISP programming port either. The T3/T4 has the port but it's backwards from the way it is accessible from the bottom.
The best version is not sold by the Chinese. It was created by Nick L on the Russian side of the project. He calls it the T4mega and it uses version 2 of the project. His PCB is all surface mount and is setup for a ATmega644 or ATmega1284 MCU. I believe he has posted his Gerber files on on his Google drive account so they can be produced but I'm not positive. At one point he was trying to sell them. I think the PCB and components for a DIY assembly we're around $80. That is hard to justify for most people though.
I was playing with my own 644/1284 design, and working on videos to compare the T3/T4, GM328, and AY-AT clones, but I got the world's worst case of the flu a couple of weeks ago that put me in the hospital, on top if being a slow disabled gimp so it will take me awhile to do much of anything on the subject.
If you want to play with the newest software that can detect a lot more components correctly (like JFETS) go with one of the through hole kits like the AY-AT or GM328. You can order the correct voltage reference and sense resistors for around $10-$15 from Mouser if you want to build a model that follows the design spec. There are also many other optional circuits available in the documentation for the project.
If you want to get it right the first time, etch your own project.
Thanks for your answer! If they all lack working ISP headers, how can it be that tons of people, especially in the EEVBlog topic are updating the firmware all the time? Ideally I would have a version that is a solder kit, so I have something to solder again :-P and still has the newest features and supports the firmware upgrades. Any thoughts on this option? www.ebay.nl/itm/2017-LCD-GM328B-Transistor-Tester-Diode-ESR-Meter-PWM-Square-Wave-Generator-Case/112632180737?hash=item1a3966b001:m:m1Hyx8m8N03J8L9MgTYT93Q
Mathijs Groothuis
If you check out the different forums like the Transistor Tester thread on the EEVBlog forum you will see you need to modify the PCB, remove the MCU (on the versions with replaceable dip packaged MCU's), or create a custom adaptor cable. It all depends on the version and what you want to do. Most people get one of the cheap USBASP programmers and either an AVR programming board with zif socket or simply add their own ISP connectors and bodged wiring. A USBASP programmer and a AVR zif socket board will cost about $2 each from China.
No offense, but the version you linked to is one of the worst I've seen. Look at the sense resistors. They are the 680R and 470k resistors. On the version you linked to these resistors have 3 numbers indicating they are 5% tollerences. The software is written in a way that requires these resistors to be as close to 680R and 470k as possible. Well.. kinda. The software assumes that all 3× 680R and all 3× 470k resistors are exactly the same value. Any deviation in these values creates problems with accuracy. This is why the design specifies 0.1% tollerences for these resistors. The software is designed to absolutely maximize the potential of the ATmega MCU's internal hardware using the absolute minimum external hardware. It's really sad that the people making these clones don't seem to understand this. The crappy clones will do the basics, but your not going to get them to do it well or with much accuracy.
I suggest you check out the official project documentation from Karl-Heinz. It's around 130 pages in a PDF, links are in this video's description. He devoted 10's of pages in how the software works and the accuracy of the device. You'll never achieve the same results by starting with out of spec hardware. I would get an AY-AT and order the correct through hole components from Mouser/Farnell/Digikey at the same time (3×680R, 3×470k, LM4040-2.5, MCP1702-5002, 16mhz crystal).
As to the EEVBlog forum thread. I am jakeisprobably. I've posted a bunch of info on there including several schematics, a detailed list of all project options across both firmware forks, and a list with links to all the parts needed from Mouser to get an AY-AT up to spec. I've also posted my schematics as they are created here although they are also available on my GitHub page.
If your going to get a version like the one linked, there is not real benefit over the basic T3/T4 clones. The 5% sense resistors kill the deal. Plus the color TFT screen really really sucks. I have almost every screen option for the project on my bench. The 1.8" is absolutely tiny and is not very good. The screen on the T3/T4 is considerably larger than the AY-AT's 1.8 TFT and the GM328 in this video.
Thanks for your reply. It's all a little overwhelming, for someone just starting with the hobby. I always meant to find a solder kit version. The one I linked also has a solder kit, so I could always buy the better components from Farnell. But I will look for a AY-AT now if you say it's better.
To be honest I do like the Banggood tester more: www.banggood.com/DANIU-3_5inch-Colorful-Display-Multi-functional-TFT-Backlight-Transistor-Tester-p-1083042.html?rmmds=search&cur_warehouse=CN because it doesn't only state the technical stuff, but also says what the component is exactly. Handy for a beginner in repair like me. But I read that this Banggood version isn't compatible at all anymore with the firmwares, and it doesn't come as a solder kit. It's quite hard to spot all these differences, I don't even see any differences between mine and the so called 'AY AT' version, except for the PCB color. What is AY AT referring to?
Thanks for your answers :-).
Mathijs Groothuis
That one from banggood has the Zener threshold circuit and infrared remote control decoder. It has 1% resistors (If I recall correctly), that's not the 0.1% specified but it's much closer than 5%. Unfortunately it's biggest down sides are the MCU is surface mounted making replacement much more difficult if you damage it. I don't believe it has the TVS diode protection either, so it only takes one tiny mistake to fry it. The other big problem is that, while it does have an ISP port, the port is configured in a way where the device can't be programmed without desoldering the LCD's ribbon cable. ..or so I've been told by reliable sources on the EEVBlog thread.
The AY-AT is probably the best clone kit. No sellers call it that, that I'm aware of. It's just the name we use because almost all of the red PCB's for the AY-AT have "AY-AT" at the end of the production number that is screen printed on the PCB. The easiest way to search for that kit is "Transistor Tester PWM," then just filter through the results for the red PCB design.
I know what it's like to try to play with electronics as a hobby. I just started a few years ago and still feel like a total newbie myself ;)