$20 LCR ESR Transistor checker project

[madires]

The long answer: The 32x39 symbol set is the companion of the 16x26 font. 39 pixels resized by a factor of two creates a symbol 78 pixels high. This matches three text lines with a height of 26 pixels each (26 * 3 = 78).

[Fuzzy Star]

The long answer: The 32x39 symbol set is the companion of the 16x26 font. 39 pixels resized by a factor of two creates a symbol 78 pixels high. This matches three text lines with a height of 26 pixels each (26 * 3 = 78).

Sorry! 
I searched  '32x39' in my config_644.h file but forgot that it's my moded file with irrelevant display sections removed 
I see that in the original config_644 there are 32x39 symbol options.

Anyway, thanks again for the new version!

[Polf]

Please tell me for what reason an error occurs Process Exit Code: 2 during compilation?
But if you disable the menu CFLAGS += -DWITH_MENU, compilation is successful.

[madires]

Let's see. It's about k-firmware and it's a warning about a potentially uninitialized variable, not really an error. I guess that the compiler is called with the option to treat warnings as errors and then returns 2. A simple solution would be to initialize the variable:

Code: [Select]

  unsigned long wish_freq = 0;


[Polf]

Thank you for your reply! Today I have successfully compiled on another PC with Windows 7 64 bit operating system installed. This means that after updating Windows 10 64-bit on the main  PC, my compiler does not work correctly.

[.RC.]

What do I need to enable to test Zeners on the AY-AT through hole model?  When I built my tester, I made sure the 180k and 20k resistors were well under 1% accuracy. 

The config has these options it seems

//#define HW_ZENER




//#define ZENER_DIVIDER_CUSTOM
//#define ZENER_R1         180000
//#define ZENER_R2         20000




//#define ZENER_UNSWITCHED




//#define ZENER_SWITCHED
//#define ZENER_BOOST_HIGH                /* high active */
//#define ZENER_BOOST_LOW                 /* low active */




//#define HW_PROBE_ZENER
//#define ZENER_VOLTAGE_MIN     1000      /* min. voltage in mV */
//#define ZENER_VOLTAGE_MAX     30000     /* max. voltage in mV */




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Thank you for your reply! Today I have successfully compiled on another PC with Windows 7 64 bit operating system installed. This means that after updating Windows 10 64-bit on the main  PC, my compiler does not work correctly.

I am running windows 10, 64 bit and have managed to get it to work.

I followed sort of this guide that madires kindly linked for me  https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/2475/

 the link for toolchain would not work for me (funnily enough it does now) and I ended up getting version avr8-gnu-toolchain-3.7.0.1796-win32.any.x86_64

I am using WinAVR on windows 10 and when I tried to compile I got an error message, the fix was to go to the installation folder for winavr on the C: drive and search for patch.exe

If you run that it opens a command prompt page.   You have to leave it open and go back to the winavr running program and it should compile. Or mine does anyway.

[vk3em]

Yes, I know, but 8.19 ohm vs 0.14 ohm is not acceptable. And most importantly, I cannot run self-calibration with this Chinese firmware; it looks like they cut off that function.

I can confirm the same problems. The printed quick start guide includes instructions for "Self-Calibration" but its not possible to get it to enter that mode. I have tried all combinations. The instructions show screen shots of firmware including self-calibration mode that is "2.xx" while the shipped firmware is "3.xx" - the lack of self-calibration mode may or may not be the cause of the erroneous readings, but on my unit as well, the ESR readings seem totally wrong, which is a real shame as ESR measurement of capacitor was the reason I purchased it! Might have to get a real ESR meter now.

Luke

[madires]

What do I need to enable to test Zeners on the AY-AT through hole model?  When I built my tester, I made sure the 180k and 20k resistors were well under 1% accuracy. 

The AY-AT doesn't come with a boost converter, it just measures an external voltage via a 10:1 voltage divider. So the only option to enable is HW_ZENER. If you want to check Zener diodes you would have to apply an external power source (<50V and a current limit of a few mA). The recommended settings for the AY-AT are listed in the Clones file.

[hoangtran]

Yes, I know, but 8.19 ohm vs 0.14 ohm is not acceptable. And most importantly, I cannot run self-calibration with this Chinese firmware; it looks like they cut off that function.

I can confirm the same problems. The printed quick start guide includes instructions for "Self-Calibration" but its not possible to get it to enter that mode. I have tried all combinations. The instructions show screen shots of firmware including self-calibration mode that is "2.xx" while the shipped firmware is "3.xx" - the lack of self-calibration mode may or may not be the cause of the erroneous readings, but on my unit as well, the ESR readings seem totally wrong, which is a real shame as ESR measurement of capacitor was the reason I purchased it! Might have to get a real ESR meter now.

Luke

Because of this long thread, I was curious, so I picked one to try. Now it's gone. And yes, a real ESR meter is a serious thing.

[vk3em]

Yesterday I ordered another unit which just might contain the ATmega324. These things are cheap enough that I'll keep at it until I get the one I want!

Call me a sucker for punishment, but after recently failing with my purchase of the LCR-TC2 from this vendor (I wanted an ATmega324 but got the LGT8F328P), I've taken a gamble on the LCR-TC1 model from the same vendor. https://www.aliexpress.com/item/1005004717377243.html

What gives me hope?

LCR-T7 / LCR-TC1:color screen / M644 chip, two functions are the same! T7 is slightly faster! The TC1 screen is slightly larger and they are all powered by lithium batteries. In addition to measuring resistance, capacitance, inductance, diodes, MOS transistors, thyristors, it can also measure additional voltage regulators, infrared decoding (limited to for Hitachi format)
Self test with automatic calibration

In the LCR-TC2 description, it does not mention M644 (since it was delivered with LGT8F328P that makes sense) nor does it mention "Self test with automatic calibration" - this also makes sense as firmware for the LGT8F328P (in my case V3.1e) cannot fit the code for self-calibration. V3.1E firmware is also horrifically buggy, cannot reliability measure ESR, or Darlington transistors, etc. I will definitely be modifying my LCT-TC2 with LGT8F328P to the ATmega328P.

I can only presume (hope) M644 mentioned in the details of the LCR-TC1 description refers to ATMega644 and so far this is the only specific mention of M644 within an advertisement that I can find. Lets see when it arrives.

Luke

[.RC.]

What gives me hope?

ha ha, well I now have gone from zero testers a month ago to two and another currently on a plane.  Then I bought six resistors for $2.57 each and six for $1.60 each to "fix up the kits" Along with a couple of precision voltage regulators and a couple of precision voltage references.

I think I am up around $80 now for the three units and the fnirsi one is just a basic basic thing.  Although in passing I wonder instead of spending large sums on through hole precision resistors.   0.1% SMD's are only a dollar each, I wonder if I could have soldered wires to them and used them instead.

Now I am thinking for zener diodes is there a boost converter module I could use to apply the required boost voltage.  Hide it in a 3d printed case connected with the battery.

The other downside is the small memory I can not fit the entire spread of options into one device. (so you do need multiple anyway) or one with the bigger chip.

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Makes me wonder about this one as I can not find a reference to this design in the clone list.  One listing I saw had a review where a photo of the rear of the board and it showed the same as the attached photo below.

https://www.aliexpress.com/item/1005005137402266.html

This a photo of the board from the internetz.

[indman]

Makes me wonder about this one as I can not find a reference to this design in the clone list. 

You don't need to think about this design as it is of no interest due to the poor quality BGR display.
Similarly, with similar clones, where such a display is used.

[madires]

ha ha, well I now have gone from zero testers a month ago to two and another currently on a plane.  Then I bought six resistors for $2.57 each and six for $1.60 each to "fix up the kits" Along with a couple of precision voltage regulators and a couple of precision voltage references.

Wow, that's expensive! A local online shop sells 0.1% TH resistors (Yageo) in single quantity for around EUR 0.25 - 0.30 (680 and 470k are 0.27).

[indman]

0.1% SMD's are only a dollar each, I wonder if I could have soldered wires to them and used them instead.

Maybe I'm wrong, 0.1% resistors are good, but for this project it is quite enough to select measuring resistors from the 1% set with a multimeter. This selection is then easily controlled using the built-in hardware tests T1-T6. It's just important that the pairs of resistors are close in resistance. I didn't notice much difference in readings compared to 0.1% precision resistors. Do not forget that this is just a SIMPLE TESTER, in which there are still a lot of factors that do not allow equating it to metrological instruments.

[.RC.]

I was just being guided by others on ways to improve on the chinese kits  https://github.com/blurpy/transistor-tester/blob/master/resources/AY-AT-J1.3.png

Is this the way to check zeners on this model.    It was a 12V Zener.   40V being input, 28V showing, so 12V Zener?

I only enabled  HW Zener

[madires]

Nice! Connect the Zener diode and the external power supply in parallel to the tester's input, while limiting the current to a few mA (typically 3 mA).

[oitar]

OK, I connected PD0 of my mega324pa(which is a configuration pin, pulled up to 5V, not used in m-firmware) to the test button, and can now use the test button properly. I did the Test, and Adjustment(now with the 1.49m) number of times, completed successfully, and saved in Profile1.
However the issue persists: 1. Zener diodes over 10 V are measured perfectly, below 10 V(or thereabout) are shown as ~1/4th of their voltage.
2.Resistors are shown in a very strange way: I put a brand new 10 kOhm(which measures 4247 Ohm after Adj) multiturn pot, and starting from 0 slowly go up. I get this in Ohms: 0.91, 70.5, 535.6, 960.2, 1224, 1610, 2104, 2424, 2601, 11.59k, 12.72k, 14.07k, 15.23k, 16.60k, 18.20k, 2418, 2569, 2854, 3043, 3329, 3615, 3862, 4187, 4322(at the end).
I.e. going linnearly, albeit low, then for a while overshooting by double, then back to low, and finnishing at around half the actual value.

Please be aware that this is NOT A FIRMWARE ISSUE, since it had a similar behaviour with the original Chinese firmware.
I would like an opinion whether this is a hardware defect(why does it complete the Adjustment then?), or a wrong port pin specified somewhere(checked number of times, schematic is very similar to the T7 in the Clones memo)?
I have checked the resistance of the 3 probes, and the readings are practically the same to GND and VCC for all 3. Also the resistance of the 3 680 Ohms, and 470 kOhms are within 0.1% of each other.

[madires]

Could you please repeat the Zener test (with a Zener <10V and another one >10V) and measure Vcc (5V) with a DMM? Is Vcc stable?

[elecdonia]

Is this the way to check zeners on this model.    It was a 12V Zener.   40V being input, 28V showing, so 12V Zener?

Another method is this:

1) Connect a 10k ohm resistor instead of the zener shown in your photo. Temporarily set the zener diode aside (not connected). Otherwise keep same connections to your 40V power supply. After replacing zener with 10k resistor then the Transistor Tester should display the DC voltage provided by your power supply (~40V).

2) Next, connect the zener to be tested directly across the 2 “voltage test” terminals of the Transistor Tester, with zener cathode (banded end) to + terminal of voltage test connector.

3) Transistor Tester should then display the actual zener voltage (12V). You won’t need to subtract the voltage displayed by the Transistor Tester from the power supply voltage to obtain the zener voltage.

The 10k series resistor limits the maximum zener test current to <4mA (when external power supply voltage is 40V).

Most  “factory built” Transistor Testers with self-contained zener test feature use a 10k series resistor to limit the test current. Although the Transistor Tester technical reference manuals provide a schematic for an optional “constant current source” for zener testing, I don’t think this extra complexity is necessary. The 10k series resistor all by itself is adequate.

[elecdonia]

Call me a sucker for punishment, but after recently failing with my purchase of the LCR-TC2 from this vendor (I wanted an ATmega324 but got the LGT8F328P), I've taken a gamble on the LCR-TC1 model from the same vendor. https://www.aliexpress.com/item/1005004717377243.html
What gives me hope?

LCR-T7 / LCR-TC1:color screen / M644 chip

I succeeded at getting a unit containing a genuine Atmel ATmega324 in Jan. 2023. I purchased it from an eBay vendor who also offered several different Transistor Tester models, quite similar to the Aliexpress listing in your post.

The item I selected was priced at $23 USD vs. $12-15 USD for all other models offered by the same vendor. The eBay vendor described it as “LCR-TC2 improved” (I expected to pay ~$23 USD because genuine Atmel ATmega324 as bare IC chip sells for >$8 USD).

Curiously my mega324 unit also displays V2.3E for its firmware. I have confirmed it contains a genuine ATmega324 (44 pins, not 32). I’m nearly ready to install OSHW Transistor Tester firmware into it. I will post my results when finished upgrading.

Please let us know what arrives for you!

[Obelix2007]

Is this the way to check zeners on this model.    It was a 12V Zener.   40V being input, 28V showing, so 12V Zener?

I only enabled  HW Zener

... connecting your z-diode is wrong for a measurement without calculation:

[elecdonia]

Is this the way to check zeners on this model.    It was a 12V Zener.   40V being input, 28V showing, so 12V Zener?I only enabled  HW Zener

... connecting your z-diode is wrong for a measurement without calculation:

Is that a 20k ohm series resistor in your photo?

[Obelix2007]

... yes, it is - this prevents the BZX83C47 from heating up. With higher current, the zener voltage increases and the distance to the measuring voltage (50 volts) becomes too small to measure accurately - with this arrangement, the measuring current is approx. 250 µA!

Regards Horst

[.RC.]

Here are some pricey ones  https://www.aliexpress.com/item/1005003670951373.html

I want upgrade 3.  "After sales upgrade，New skin shrimps will be given away and accidentally burned within one year，"   

I think they mean a different firmware and a one year warranty.

I guess this is the same basic model without the accidentally burnt shrimp skins. https://www.aliexpress.com/item/1005003680113751.html

All claim 48V zener capability.

[elecdonia]

Here are some pricey ones  https://www.aliexpress.com/item/1005003670951373.htmlI want upgrade 3.  "After sales upgrade，New skin shrimps will be given away and accidentally burned within one year，"   

Interesting that this vendor posts photos of the PC boards. Most do not. Also all 3 of their PC board photos show MCU chips with 44 pins. To the best of my knowledge there aren’t (yet) any cloned/faked Atmel MCU chips with 44 pins. Popular “fake” Atmel MCU chips all have 32 pins. Yet another “tell” is the presence of j4, a 6-pin Atmel ISP programming header in the traditional 2x3 pin format. Transistor Tester PC boards with clone/fake MCU never have this 2x3 pin programming header. Some do have what appears to be a programming header, but never in the 2x3 pin style.

Chinese-> English is often entertaining. For example:

https://www.ebay.com/itm/324243157482

Product parameters:
Product Type: Electronic Tube Amplifier
Number of channels: two channels
Output rent resistance: 4-8 euros
Power supply: AC12V
Product net weight: 170g
Product size: 81*81*43MM