$20 LCR ESR Transistor checker project

[Obelix2007]

... https://de-m.banggood.com/Original-Hiland-M644-Transistor-Tester-LCR-Diode-Transistor-Zener-Quartz-Measurement-p-1279042.html

Greeting Horst

[mojoe]

I have an old MK-328 that I bought several years ago. I think I flashed it back then, as when it powers on, it says "GM328" and the "Show Data" menu reports firmware "1.14k".

Attached is a picture of the front of the case (from the net, but mine is exactly the same). Also, a picture of the PCB (again from the net).

It has a real 328P with an 8 MHz crystal. In the upper left corner are several unpopulated pads. Near the center are missing C9, U2, D2 & L1.

Can anyone tell me what the missing components are for? I assume that some may be for zener testing. Is there a full schematic, showing the missing components? Is it worth the trouble adding a rotary encoder and other missing features?

If I hold down the power button, I get a menu with several choices. Short presses cycle through them, and a long press selects one.

[coromonadalix]

mmm maybe was for a rechargeable battery ??  you have diodes and a inductor ...  and the 2 diodes seems to protect against an inverted supply

r22  would be some limiting resistor or can or could blow if over current ?


you would need to dismantle it and try to make a schematic

many teardowns on the web show no populated parts .....

[madires]

Can anyone tell me what the missing components are for? I assume that some may be for zener testing. Is there a full schematic, showing the missing components? Is it worth the trouble adding a rotary encoder and other missing features?

Looks like a signal input stage for the frequency counter. A rotary encoder helps with menu functions. And the firmware is a modified k-firmware (the latest k-firmware is 1.13k). If you like to update please see https://github.com/kubi48/TransistorTester-source/tree/master/trunk/mega328_MK-328,

[indman]

In the upper left corner are several unpopulated pads. Near the center are missing C9, U2, D2 & L1.

U2 is the place to install the same +5V stabilizer as U6, just a slightly smaller form factor.
C9 is an additional capacitor for filtering the +5V output voltage. In some MK-328 models, 47μFx16V is installed in this place. L1 is an inductance for additional filtering of the input voltage to the stabilizer U6 (instead, jumper R14 is now installed). D2 is a protective diode. In general, these additional elements are not needed for this circuit, since it works stably without them.
Connector J5 and the circuit for it are an input signal bufer -  for the frequency counter option (as dear madires answered correctly).

[Per Hansson]

Hi, I'm looking for this kind of tester. I've checked the PDF (https://github.com/madires/Transistortester-Warehouse/blob/master/Documentation/English/Clone-Comparison-Chart.pdf) that lists all the clones and it looks like the Hiland M644 is a decent option. But the PDF is a few years old and I can't find this particular model anywhere on eBay or Aliexpress.

I liked that it can test Zener diodes above 5V and would have liked it to have external power too.

Are there updated recommendations? If not, what happened to this model and where to find it?

Cheers!

... https://de-m.banggood.com/Original-Hiland-M644-Transistor-Tester-LCR-Diode-Transistor-Zener-Quartz-Measurement-p-1279042.html

Greeting Horst

Just adding my $0.02 opinion: the Hiland M644 is not worth $40
It has quite a few design mistakes that reduce the accuracy and usefulness of the device.
But on this note I wonder if any nice DIY projects exists to make a tester based on the Atmega 644 or 1284 chip that still stays true to the original intent of keeping this a simple low cost device?
On the previous page a very advanced SMD version was shown but I'd be more interested in a cut down version.
Maybe the PCB could be designed to both accept through hole and SMD components (or two separate PCB designs).
So far the closest designs I've found are these but I don't know if they have been published?
https://www.eevblog.com/forum/testgear/show-us-your-$20-transistor-tester-enclosures-and-mods/msg1201483/#msg1201483
https://www.eevblog.com/forum/testgear/show-us-your-$20-transistor-tester-enclosures-and-mods/msg4851821/#msg4851821

A cursory Google search also brought up this design, but I could not find the original author of it:
https://oshwlab.com/amilio.spring/ESR-Atmega-644

I think it would be nice if someone competent in PCB design would make a project on Github to make the hardware as accessible as the software is.
I could try myself but I'd probably make the same kind of mistakes that the original Hiland M644 design has as I'm not a PCB designer by trade...

[madires]

For the 644/1284 dev kit please see https://github.com/madires/Transistortester-Warehouse/tree/master/Hardware.

[Per Hansson]

Thanks madires! Is the display PCB also available?
I just found a post by snapper on the German forum where he made an updated version of the Hiland M644 PCB.
I'm not sure if he published it anywhere though?
Relevant posts:

https://www.mikrocontroller.net/topic/transistortester-avr?page=32#7511818
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4886483/#msg4886483

[coromonadalix]

same for a mega 2560 ... nothing so far  ...  but code is there ...

[madires]

Is the display PCB also available?

No, it's just a 3.3V LDO and level shifters (74HC4050, 74HCT125).

I just found a post by snapper on the German forum where he made an updated version of the Hiland M644 PCB.
I'm not sure if he published it anywhere though?

AFAIK, he didn't publish the PCB. However, you could ask him for a copy.

[madires]

same for a mega 2560 ... nothing so far  ...  but code is there ...

I'm using an Arduino Mega 2560 clone for testing, especially for displays with an 8-bit parallel bus.

[Bibbbi]

Has anyone successfully managed to compile the madires Transistor project via the IDE Platform VSCode/PlatformIO instead of using the old WinAVR environment?

How does it work? 

[jdev99]

I tried your settings with a 16MHz ATmega644 tester but couldn't reproduce what you've seen. Also after running the RCL monitor a 1µF cap measured fine for all probe combinations.

Can you use the ATmega644 with a 16MHz crystal?
I tried it and it does not work. If I look at the fuse settings for oscillators, it only goes to 8Mhz.
What am I missing?

[madires]

Yes, a 16 MHz crystal works fine. The fuse bits are the same as for an 8 MHz quartz (external crystal, 1:1 prescaler). But you need to compile the firmware for 16 MHz (-> Makefile).

[jdev99]

I now installed a ATmega644 + 16MHz crystal, and it works great.
The only other thing I want to know is how to improve the zener test values.
A 5.1v read as 5.44v and a 12v read as 13.5v.

[madires]

Could be the test current (too low). Low wattage zeners need about 3 - 5 mA.

[jdev99]

It draws 3.7mA for the 5.1v, so it seems like there is enough current. 

[indman]

jdev99
A competent and simple solution, as indicated in the screenshot. Selection of the most optimal current and its stabilization for safe testing of high-power and middle(low)power zener diodes.
For more precise adjustment of the measured voltage on the zener diode, in k-firmware the Makefile contains lines for the input resistor divider
# Voltage divider for the external zener voltage measurement 180k / 20k = 10/1
CFLAGS += -DEXT_NUMERATOR=10
CFLAGS += -DEXT_DENOMINATOR=1
Instead of a decimal value, you can use the following numbers for smoother voltage adjustment
CFLAGS += -DEXT_NUMERATOR=100
CFLAGS += -DEXT_DENOMINATOR=10
In your case, to reduce the voltage, you can, for example, try the following values
CFLAGS += -DEXT_NUMERATOR=120
CFLAGS += -DEXT_DENOMINATOR=10

For m-firmware, similar divider settings are in the config.h file
#define ZENER_DIVIDER_CUSTOM
#define ZENER_R1         180000
#define ZENER_R2         20000

[rherber1]

I have purchased an LCR-TC2 which appears identical to that in Swainster's pics(Reply #8574 on: May 09, 2023, 05:00:09 am). My pcb is marked T7-PLUS V2.0 also and f/w is V3.1E.

My tester exhibits odd behaviour when measuring resistors of 15 Ohms and 18 Ohms in that it identifies them as Inductors with some arbitrary value of inductance and with the nominal resistance shown. If I use 12 Ohms or 22 Ohms these values are correctly identified as Resistor with the nominal values displayed.

The ability of this tester to produce an accurate value of resistance appears to be quite poor. I measured a nominal 56KOhm resistor with two different multimeters and both produce a reading of 56k6 Ohms. The TC2 produces a value of 58k07 - not what you would call close to the result of both multimeters.

[wasedadoc]

Could be the test current (too low). Low wattage zeners need about 3 - 5 mA.

No, the effect would be the opposite.  Low current through a zener gives a lower voltage across it, not higher.

[indman]

The Zener stabilization voltage may differ from the rated voltage even with the current allowed for it. Therefore, to be sure that the readings are correct, you must first provide current from the stabilized power supply through the zener diode, which is indicated in the datasheet for it, and then measure the voltage drop with a multimeter. This will be the right choice.

[madires]

I have purchased an LCR-TC2 which appears identical to that in Swainster's pics(Reply #8574 on: May 09, 2023, 05:00:09 am). My pcb is marked T7-PLUS V2.0 also and f/w is V3.1E.

My tester exhibits odd behaviour when measuring resistors of 15 Ohms and 18 Ohms in that it identifies them as Inductors with some arbitrary value of inductance and with the nominal resistance shown. If I use 12 Ohms or 22 Ohms these values are correctly identified as Resistor with the nominal values displayed.

Have you run the self-adjustment (shorting all three probe pins)? BTW, that TC2's MCU is an LGT8F328.

[rherber1]

Have you run the self-adjustment (shorting all three probe pins)? BTW, that TC2's MCU is an LGT8F328.

That procedure is not mentioned anywhere in the instruction pamphlet - so, no, I didn't do it.

Have done it now shorting 1-2-3 together and running a test. Shows 0.11 Ohms 1-2 and 0.14 Ohms 2-3. Then ran a test on the 15 Ohm resistor again and no difference - still says it is an inductor.

[madires]

Bummer! Unfortunately some of the tester clones with an alternative MCU come without the self-adjustment feature.

[csuhi17]

Have you run the self-adjustment (shorting all three probe pins)? BTW, that TC2's MCU is an LGT8F328.

That procedure is not mentioned anywhere in the instruction pamphlet - so, no, I didn't do it.

Have done it now shorting 1-2-3 together and running a test. Shows 0.11 Ohms 1-2 and 0.14 Ohms 2-3. Then ran a test on the 15 Ohm resistor again and no difference - still says it is an inductor.

https://youtu.be/KPdoprtrfBg?si=xw6ZLrNqGqUZCcVY&t=130

Did the calibration go well for you, like in the video?

It happened to me that the calibration failed, because the resistance value was higher with the short between me.
After pressing Test, it showed two or three resistances between the test points.