$20 LCR ESR Transistor checker project

[madires]

5-pin ISP header (SWD), one pin connected to MCU's pin 21 -> LGT8F328

[Calambres]

Thanks a lot. I suppose there's nothing I can do with this tester other than asking AliExpress for a refund 

[indman]

I suppose there's nothing I can do with this tester other than asking AliExpress for a refund 

Right! It is necessary to return such a low-quality product back to the seller and demand a refund of the money spent.

[Calambres]

I'm afraid the return postage cost to China is greater than the cost of the item itself 

[Calambres]

This chinese seller is really wicked 

I sent him a message through the AliExpress messaging service explaining my concerns about the impossibility to perform a calibration with this tester. On next day the seller answered, in a very amicable way, to send him a video showing the problem. Everything OK so far so I did a couple of videos, one using the supplied 3 pin header and another shorting the also supplied three DuPont cables with mini grabbers. I uploaded both of them to my youtube channel.

So far so good... except for one little detail: AliExpress does not allow neither sending files through their messaging system nor even sending youtube links. As soon as the system detects a youtube link or even the word "youtube", the message is zapped and a menacing warning is produced:

Note: This message contains prohibited content and hasn't been sent. Any further messages of this nature may result in account restrictions.

Isn't it wicked? 

Of course the seller is perfectly aware of this AliExpress behaviour and asks for a video just to make all things difficult 

I've sent a note to the seller explaining what happened (without using the evil "youtube" word). Let's see what the seller comes with now 

Meanwhile, if you feel courious and want to take a look at those two aforementioned videos:

[Calambres]

Ah, by the way, anyone knows what is hFEr?

[indman]

Ah, by the way, anyone knows what is hFEr?

hFEr=REVERSE_HFE
"All transistors have inverse Hfe, since you can always swap the collector and emitter. This is equivalent (but not strictly identical - Hfe is a large signal, BF is a small signal hybrid signal) to the SPICE BR parameter, just as BF is equivalent to Hfe."

Link: https://www.physicsforums.com/threads/what-is-reverse-hfe.305553/

[Calambres]

Thanks, mate!   

[4thDoctorWhoFan]

I did not realize these testers had a selftest/cal mode. lol
I tried it on my T7H and it worked.  I guess I have older firmware as mine says v1.1 (No E after the 1.1 like yours in the pictures)

Perhaps it's just a firmware issue and not a hardware problem.

[madires]

The self-adjustment feature is simply missing in the modified firmware for that specific alternative MCU. Either it's the lack of flash memory or the manufacturer is unable to adapt the self-adjustment to the other MCU. Because ATmegas are quite expensive at the moment some clone manufacturers switched to other MCU types. And those testers are a disaster, mostly thanks to a poorly ported firmware.

BTW, TC-1 and similar clones run a modified k-firmware (fancy graphics, less features).

[Calambres]

Then which is the best option today? 

[indman]

Then which is the best option today? 

M328Kit+TFT RGB(GM328A) ATMega328 Dip form factor. It is easy to make an adapter for this clone for ATMega644.
This is the best option for today, so as not to get a fake and wasted money, nerves and time!

[Calambres]

Then which is the best option today? 

M328Kit+TFT RGB(GM328A) ATMega328 Dip form factor. It is easy to make an adapter for this clone for ATMega644.
This is the best option for today, so as not to get a fake and wasted money, nerves and time!

Well, that's the one I have (the T7-H was purchased for a friend).

Mine is the M328Kit+TFT(AY-AT) but has a buggy SW that prints trash instead of some symbols. Don't really know how to update the SW. I must find a "guide for dummies" somewhere 

[Obelix2007]

Bohu has updated the Czech, German and English PDF documentation for 1.49m: https://github.com/madires/Transistortester-Warehouse/tree/master/Documentation

... Look to the Documentation of madires.

Regards Horst

[morgan_flint]

Then which is the best option today? 

M328Kit+TFT RGB(GM328A) ATMega328 Dip form factor. It is easy to make an adapter for this clone for ATMega644.
This is the best option for today, so as not to get a fake and wasted money, nerves and time!

Don't you think the Hiland M644 is also a good option?

A bit pricey now (nearly $40 at Banggood when, f I remember well, I got it under $20) but already M644 and complete with prescaler and voltage booster for zener testing. AFAIK, no fake CPUs in this one also.

[indman]

Don't you think the Hiland M644 is also a good option?

Yes, this is also a good option, but now it has almost disappeared from sales and sellers' offers. In addition, it is equipped with a monochrome display, which slightly reduces its merits.

[morgan_flint]

True, it's hard to find now, even Banggood is out of stock now (the ad says "Restocking. Expected to ship before Jun 15").

The only place that seems to have stock is here at taobao, (and very good price, $17 + shipping, I suppose). Unfortunately, I don't know how to buy at Taobao or if they would ship outside China. This seller also has two other versions of the tester, and he seems to be the manufacturer of the kits; maybe he would be interested in making a 644 version with a color screen if somebody tells him 

[snapper]

hi,
i've often bought from taobao, but unfortunately that only works through a so-called sales agent and causes additional costs such as overseas shipping and agent fee. and depending on the country, there may be additional customs duties because bhiner does not collect them immediately, e.g. aliexpress or ebay.
best regards

https://www.bhiner.com/

[elecdonia]

Ah, by the way, anyone knows what is hFEr?

hFEr=REVERSE_HFE
"All transistors have inverse Hfe, since you can always swap the collector and emitter. This is equivalent (but not strictly identical - Hfe is a large signal, BF is a small signal hybrid signal) to the SPICE BR parameter, just as BF is equivalent to Hfe."

Link: https://www.physicsforums.com/threads/what-is-reverse-hfe.305553/

There is a class of small-signal BJT transistors which have “reverse Hfe” of similar magnitude to their forward Hfe. In addition their E-B reverse breakdown voltage is similar to the E-C breakdown voltage, typically ~25V.

These devices are marketed for “audio muting” applications at analog line-level signal levels ( <5V RMS ). The E and C pins are interchangeable. A typical application circuit sends the output from an opamp through a ~1k ohm series resistor followed by the audio muting transistor operating as a controllable shunt to ground. Application of base current to the audio muting transistor provides >80dB of audio muting. The transistor is an open circuit when the base is reverse-biased. The reverse bias voltage is usually >10V. This is large enough to prevent clipping of the audio signal.

[snapper]

True, it's hard to find now

If you add up the sales agent fee, shipping costs and taxes/duties, it's just as expensive as this one and he can deliver immediately

https://www.elecbee.com/en-29467-Original-M644-Transistor-Tester-LCR-Diode-Transistor-Zener-Quartz-Measurement-Frequency-Counter-PWM-Wave-Generator-Online-ESR

Economic Shipping $5.00 About 5-15 Days to EU

[Pukker]

How frustrating can the Chinese be?
Nice project by Markus Frejek, Karl-Heinz Kübbeler and all others,
the Chinese must be thinking "Aha, nice money making project"
They started making and selling useful versions.
Now they are back in their core business, MAKING FAKE. AARCHHHH

[Yuriy_K]

For k-firmware using ILI9341 developed a new font for outputting 8 lines. In the original version, 7 lines were displayed. There are a lot of changes, now I'm checking all the output options on the screen. Who is interested write.

An example of a full font and an example of measurement in the photo...

[elecdonia]

Just adding another data point on the LCR-TC2 to this thread. Old vs new version, both from "Z industry store" on Aliex 18 months apart. New: Custom case based on original generic case, f/w v3.1E, PCB T7-PLUS v2.0, unmarked 32 pin MCU

This MCU is likely to be LGT8F328P.  Other EEVblog posts report successfully replacing LGT8F328P with Atmel ATmega328P. The hardware mod is simple: Only a few pins have different functions. However, existing -K or -M firmware needs modification for mega328P to work with this PC board. When time permits I plan to try this myself.

This week I received 5x LGT8F328P boards which are (somewhat similar) to the popular (Arduino) "pro-mini" board. A "boards" definition package is available for using these LGT8F328P boards with the Arduino IDE. I intend to experiment with Transistor Tester software which has been ported to the LGT8F328P. But first I will get familiar with the LGT8F328P by comparing its performance to Atmega-based Arduino boards (which I've been using for >10 years).

To me the LGT8F328P has an interesting feature set: Its I/O pins have full 5V capability, and a "handful" of them (not all) are rated at 80mA. This may be useful for the Transistor Tester because larger I/O output current corresponds to lower internal resistance/impedance. This might improve accuracy for measurements of small resistance and for capacitor ESR. The LGT8F328P would get even more attention from me if the manufacturer introduced a version with 64k flash.  

[vk3em]

I am thinking about building my own LCR tester based on one of the open hardware designs. I am looking for something M644 based and prefer SMT components rather than through hole.
I will get the PCB made professionally so plated holes and vias is not an issue. I have found the Mega 4GSL but are there others I have missed? Happy to consider all options.

Cheers
Luke

[Yuriy_K]

I show my version of the conversion of Hiland M644 to ILI9341. Changes in the scheme and pictures of modernization and measurements. So far, only what I have debugged.