$20 LCR ESR Transistor checker project

[Piotrix]

Good evening everybody , This is my first post on EEVblog, though I am  lurker for many years

  Question:
Which tester to buy nowadays and not get a fake Atmel chip? ,  I understand that these 2:
  aliexpress.com/item/1005003606018640.html or
  aliexpress.com/item/1005003678038543.html
  (GM328A the one with terminals on both sides of the PCB) ,  are right, are they?
  By the way, what is the difference between them. As far as I understand the difference is only in LCD screen, but what is exactly the difference?

Or is it better to buy an assembly kit, and then I can chose  resistors and caps with tighter specs   for more accurate measurements. Like this one: aliexpress.com/item/32706710335.html
Basically what I want is a real Atmel chip + the ability modify the tester to get the most reliable and accurate measurements.
Which way should I  go?

[Yuriy_K]

Like this one: aliexpress.com/item/32706710335.html
Basically what I want is a real Atmel chip + the ability modify the tester to get the most reliable and accurate measurements.
Which way should I  go?

The kit uses a display that allows the use of 16 MHz quartz. In the previous examples, you can get a BGR display that works with only 8 MHz quartz ...

[madires]

A treat for the summer break:

v1.50m
- Removed temporary option UI_PROBE_REVERSED_X as it's not needed anymore.
- Option to display battery status in the last line after showing the probing result (UI_BATTERY_LASTLINE).
- Option to display a small battery symbol to indicate the battery status (UI_BATTERY).
- Added battery symbols to most fonts. Also supplemented some fonts with probe numbers with reversed foreground/background.
- Added option for a long reset pulse for an NT7538 LCD controller to the ST7565R driver (LCD_LONG_RESET).
- Added test function for photodiodes (SW_PHOTODIODE).
- Option to scroll menues page-wise instead of item-wise (UI_MENU_PAGEMODE, suggested by indman@EEVblog). Speeds up menu operation with graphics displays.
- Added two new colors to colors.h (COLOR_PALE_GREEN, COLOR_PALE_RED, suggested by .RC.@EEVblog).
- Updated Brazilian Portuguese texts (thanks to wandows@EEVblog).
- Updated Russian texts (thanks to indman@EEVblog).
- Updated Polish texts #2 (thanks to Jacon@EEVblog).
- Updated Spanish texts (thanks to pepe10000@EEVblog).

Please download at:
- https://github.com/madires/Transistortester-Warehouse/tree/master/Firmware/m-firmware
- https://github.com/kubi48/TransistorTester-source/tree/master/Markus

[pepe10000]

Hello.

Thank you madires for the gift for the summer holidays.

Attached the update of the Spanish language file with the latest news.

All the best.

[indman]

Thanks madires!
I have updated the Russian translation of the pdf documentation for version 1.50m as well as the language file.

[Yuriy_K]

Thanks madires!

Checked the v1.50m  on the HilandM644 color variant. There is a warning, do not use

/*
 *  fixed cap for self-adjustment
 *  - see TP_CAP and ADJUST_PORT in config-<MCU>.h for port pins
 *  - uncomment to enable
 */

//#define HW_ADJUST_CAP 

Error! - after adjustment

Haven't found any other comments yet.

[madires]

Is the cap for self-adjustment an MLCC? If so, please try a film cap.

[siealex]

1.50m, GM328A with ATmega in a DIP case. Strange behavior in the Generator mode: rotating the encoder knob exactly by one step changes the frequency in an unpredictable way, e. g. twice, in the opposite direction, by a random step or all the way up to 2 MHz. In other modes the encoder behaves correctly. Do I have wrong encoder settings or is it a bug in the generator mode?

[Yuriy_K]

Is the cap for self-adjustment an MLCC? If so, please try a film cap.

Thanks Madires!    I picked up a capacitor by analogy with a film capacitor MLCC. Everything began to work correctly. Shown in pictures...
The previously standing capacitor worked normally for more than 3 years. I don’t know what happened to him, but the readings differ from those shown in the right picture.

[madires]

1.50m, GM328A with ATmega in a DIP case. Strange behavior in the Generator mode: rotating the encoder knob exactly by one step changes the frequency in an unpredictable way, e. g. twice, in the opposite direction, by a random step or all the way up to 2 MHz. In other modes the encoder behaves correctly. Do I have wrong encoder settings or is it a bug in the generator mode?

Could be the encoder settings or a cheap/dirty/worn encoder. Since the encoder's turning speed impacts the frequency change in the signal gen (faster -> larger change) any issues will be more visible.

[siealex]

No, it was in fact a wrong setting: 2 pulses per notch instead of 4. Now the behavior is way more adequate in all modes.

[siealex]

A couple of questions on color graphic displays.
1. Is it possible to type text with 1 px offset from all edges? If I define a global offset, that line is not cleared at all and displays garbage.
2. Can small fonts (8x8) be upscaled twice vertically without losing flash space?

[siealex]

A small visual bug. Graphic display, 8*8 font (font_8x8_iso8859-2_hf.h). Character "q" is shifted one pixel right, it should be:
 0x00,0x7E,0x63,0x63,0x63,0x73,0x6E,0x60,   /* 0x61 q */

[madires]

1. Is it possible to type text with 1 px offset from all edges? If I define a global offset, that line is not cleared at all and displays garbage.

You could modify the display driver to do that. However, it would be only possible for display controllers supporting address windows, but no for controllers with pages (8 bits heigh addressing bars).

2. Can small fonts (8x8) be upscaled twice vertically without losing flash space?

That should be feasible with a driver modification (see LCD_Symbol() of a driver supporting SYMBOL_RESIZE).

[tofof]

What is the current consensus on the better chip for this project, a 324 or a 328? I have contacted many vendors of the T2 through ebay requesting board photos, to see if any of them do indeed have a genuine 324 inside as a few posters have managed to luck into. Alternatively, the german Joy-It T7 seems to be a safe way of getting a 328.

Is there any compelling advantage of one of these chips over the other?

[madires]

The ATmega324 has more I/O pins which is great for addtional hardware options and driving a display via hardware SPI. Unfortunately, the pin assignment of tester clones is regularly screwed up and you won't get hardware SPI without some modifications.

[Jacon]

Hi Marcus & T-Checkers,

Attached please find updated Polish translation file 
Good for discovering photovoltaic effect in various elements 

[TankedThomas]

Since there's the WIP firmware for this chip

What firmware, which is tested and fully functional, are you going to program into the LGT8F328 chip?
My advice - do not waste your time, but change the chip to a classic ATMega328, for which there are author's working firmware.

I don't believe it's fully functional nor up-to-date, but this is the firmware I was thinking of: https://github.com/DurandA/transistor-tester-lgt328p

To be honest, I don't think I have the skills to remove and solder SMD chips. My eyesight isn't great (though I do have a microscope I can use) and I don't currently have rework equipment, though I do plan to get a hot air gun for it soon.

I agree with indman. At this point in time I think it will be far easier to replace the LGT8F328 with an Atmel ATmega328P. The required PC board modification is relatively simple.

I obtained a quantity of LGT8F328 "Arduino compatible" boards. These boards resemble the Arduino Pro-mini. They come with a bootloader installed and are programmed with a standard USB-TTL adaptor. I was curious to see what they are like. So far I succeeded at programming them after installing the LGT8F328 "boards" package into the Arduino IDE. These boards will run many standard Arduino sketches (such as "blink").

But I think it will still require considerable time and effort to modify existing Transistor Tester software for the LGT8F328.   

I'm not sure how to make the modifications required to swap the chips and use a full 6 pin header though - maybe the instructions are in this thread but I didn't see them when looking. If I understand correctly at least two of the pins have to be swapped.

I just have Raspbian Lite (i.e. CLI-only) installed on my main Raspberry Pi, so I don't have the full Arduino IDE to use (I do on Windows but I don't know how I'd hook the tester up to my PC), but even so, I think it's just a matter of me not knowing how to hook up the wires properly to the GPIO pins.

[Yuriy_K]

To everyone who uses my firmware. You can correctly identify JFET pins by looking at smaller Cg= readings ... Sample measurement in the picture...

[indman]

Yuriy_K,this is certainly good, but I don’t understand how knowing the correct drain and source will fundamentally change the way JFETs work, in which the channel has a symmetrical structure?

[moimem]

hello everyone
I compiled V1.50m and tried to test the DHT22 with my LCR-T4 and it was always detected as DHT11 and showed erroneous temperature and humidity so i checked the DHTxx.c code and found that it defaulted to DHT11 and i have to long-press the button twice to switch first to auto-mode then to the DHT22 sensor  which is not straightforward. i suggest 2 ways to solve this issue:
- add a submenu to select between DHT11 and DHT22
- use the fact that byte 2 and byte 4 in the DHT 11 are always 0 to make a 99% accurate guess between dth11 and dht22

[indman]

moimem,maybe the Test button works badly or unreliably?
I don't see any difficulty in the standard madires solution for picking the sensor type.

[madires]

Or you could have simply read the README file which explains the operation of the DHTxx tool?

[Maniaxx]

Is the GM328A able to test horn caps (e.g. 82V 15000uF)? I'm aware of the 5V, 7mA limit (regarding diacs, triacs) as stated in the manual but i'm not sure if this affects caps as well as the 82V is just the max voltage.

[madires]

Should be able to measure the capacitance (needs some time, be patient). I guess the ESR is going to be too low.