$20 LCR ESR Transistor checker project

[Aldo22]

Feliciano posted a link to a list just four posts earlier.

Yes, but I'm not sure how current this list is.
There are TC1 and T7 with APT32F172K8T6 in them, which are not listed there.
It's difficult to say what you're actually getting.

[indman]

Feliciano posted a link to a list just four posts earlier.

Yes, but I'm not sure how current this list is.
There are TC1 and T7 with APT32F172K8T6 in them, which are not listed there.
It's difficult to say what you're actually getting.

Sorry, but I'm personally already tired of sorting out the varieties of Chinese shit that they have been putting on the market lately.
Maybe someone else can do it better than me. 
If you want to get a real product, then the best option is to assemble the tester with your own hands from the very beginning according to the original author's project, using high-quality components.

[gipetto]

Feliciano posted a link to a list just four posts earlier.

Yes, but I'm not sure how current this list is.
There are TC1 and T7 with APT32F172K8T6 in them, which are not listed there.
It's difficult to say what you're actually getting.

Sorry, but I'm personally already tired of sorting out the varieties of Chinese shit that they have been putting on the market lately.
Maybe someone else can do it better than me. 
If you want to get a real product, then the best option is to assemble the tester with your own hands from the very beginning according to the original author's project, using high-quality components.

That gets said a lot but it's hardly necessary. as others have said there are no fake dip mcu. so if i was looking for one i'd chose something that can be hooked to a 9v square battery, ( the 18650 3.7v cells may not work with all components) although there's not always a foto of the dip ic, you usually get a foto of the back of the pcb. make sure you get one with two rows of 14 pins, which is the dip 28 package of the atmega328p. I just checked a chinese site and although there's a lot of fakes, the dip pcbs are easy to see.

[elecdonia]

Stated another way: “You get what you pay for.”

Unfortunately all of the currently available cheap LCR-style Transistor Testers which are housed inside cream-colored plastic cases are garbage. Please do not buy any of them. 

Starting a bit over a year ago the Chinese manufacturers of these LCR-style Transistor Testers abandoned the (original design) Atmel ATmega324 MCU chip in favor of the (much cheaper) APT32F172K8T6 or LGT8F328P MCU chips. However these substitute MCU chips cannot run any of the (excellent quality) open-source Transistor Tester firmware. Unfortunately the non-upgradable firmware which comes in these “cheap” LCR-style units barely works at all.

These alternate MCU chips are made by smaller Chinese semiconductor manufacturers. They cost only about $0.25 USD each. In contrast a genuine Atmel/Microchip ATmega324 MCU now sells for $5-9 USD each as a bare IC chip. Therefore it is impossible for anyone to sell an LCR-type Transistor Tester containing the Atmel ATmega324 MCU for <$25 USD.

I did succeed at purchasing a model LCR-TC2 “V2.3E” Transistor Tester recently which contains the proper (original design) Atmel ATmega324 MCU but it cost me nearly $40 USD. Although more expensive, this unit fully supports the open-source Transistor Tester firmware, both k- and m- variants. This makes it well worth the extra cost. More details may be found in the following posts:

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4653559/#msg4653559
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4687568/#msg4687568
https://www.eevblog.com/forum/testgear/lcr-t7-tester-reliable/msg4603333/#msg4603333
https://www.eevblog.com/forum/testgear/lcr-t7-tester-reliable/msg4606021/#msg4606021

[hapless]

I like DIP because of the ease of swapping out the chip. What would be the advantage of an ATmega324 over ATmega328 to pay a premium for a tester based on it?

[elecdonia]

I like DIP because of the ease of swapping out the chip. What would be the advantage of an ATmega324 over ATmega328 to pay a premium for a tester based on it?

1) Some of us want a Transistor Tester which comes in an attractive “toolbox-friendly” finished plastic case with a self-contained USB rechargeable battery, rather than an unenclosed PC board with a loose 9V battery dangling by its cable.

2) High-quality LCR-style units contain the ATmega324 MCU in a 44-pin TQFP package. In contrast, “cheap” LCR-style units have 32-pin MCU chips which probably aren’t the Atmel ATmega328P. However there aren’t yet any alternative “cheap” MCU chips which come in 44-pin TQFP packages. Therefore if a Transistor Tester contains a 44-pin TQFP MCU chip this indicates the MCU is likely to be an authentic Atmel ATmega324, rather than some dodgy $0.25 USD MCU with unknown architecture running poorly designed Chinese firmware which cannot be upgraded.

3) Transistor Testers with ATmega324 can be upgraded to ATmega644 to get twice as much flash (64k vs. 32k). This enables activating all of the advanced features offered by some versions of the open-source Transistor Tester software. The ATmega324 and ATmega644 have the same physical dimensions and pinout.

[hojnikb]

Feliciano posted a link to a list just four posts earlier.

Thank you, i've totally missed it. I see there are numerious variations and with different MCUs 

[hojnikb]

Stated another way: “You get what you pay for.”

Unfortunately all of the currently available cheap LCR-style Transistor Testers which are housed inside cream-colored plastic cases are garbage. Please do not buy any of them. 

Starting a bit over a year ago the Chinese manufacturers of these LCR-style Transistor Testers abandoned the (original design) Atmel ATmega324 MCU chip in favor of the (much cheaper) APT32F172K8T6 or LGT8F328P MCU chips. However these substitute MCU chips cannot run any of the (excellent quality) open-source Transistor Tester firmware. Unfortunately the non-upgradable firmware which comes in these “cheap” LCR-style units barely works at all.

These alternate MCU chips are made by smaller Chinese semiconductor manufacturers. They cost only about $0.25 USD each. In contrast a genuine Atmel/Microchip ATmega324 MCU now sells for $5-9 USD each as a bare IC chip. Therefore it is impossible for anyone to sell an LCR-type Transistor Tester containing the Atmel ATmega324 MCU for <$25 USD.

I did succeed at purchasing a model LCR-TC2 “V2.3E” Transistor Tester recently which contains the proper (original design) Atmel ATmega324 MCU but it cost me nearly $40 USD. Although more expensive, this unit fully supports the open-source Transistor Tester firmware, both k- and m- variants. This makes it well worth the extra cost. More details may be found in the following posts:

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4653559/#msg4653559
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4687568/#msg4687568
https://www.eevblog.com/forum/testgear/lcr-t7-tester-reliable/msg4603333/#msg4603333
https://www.eevblog.com/forum/testgear/lcr-t7-tester-reliable/msg4606021/#msg4606021

Looks like LGT8F328P could be a better bet, since someone actually tried to port alternative firmware to it
https://github.com/DurandA/transistor-tester-lgt328p

Anyone bought and used this MCU with this firmware? Is it even possible to know if you're getting LGT8F328P or APT32.

[Feliciano]

• We already had a short discussion about DurandA approach. You can go back to the posts of July 23, 2022 of this thread
• Unless the vendor shows an internal photo (and even in that case we cannot be 100% certain), you cannot know for sure what you're going to get untill you have it in your hands. For instance, last July I bought a TC1 and a T7, for $20+ each, from different Amazon sellers. One was the real ATmega, the other was a 32pin clone

P.S. Regarding the table of clones: There are so many variants lately, and the totally chinese ones are not currently supported by OSHW, so there will be not so useful to say "the same box, but with an MCU not currently supported".

[hojnikb]

• We already had a short discussion about DurandA approach. You can go back to the posts of July 23, 2022 of this thread
• Unless the vendor shows an internal photo (and even in that case we cannot be 100% certain), you cannot know for sure what you're going to get untill you have it in your hands. For instance, last July I bought one T1 and one T7 from Amazon, for $20+ each, from different sellers. One was the real ATmega, the other was a 32pin clone

Guess i'll have to roll the dice and see what i get. It's cheap though, so it won't matter that much.

[mcgyvr81]

Hello folks,

I just found out about this thread on eevblog forums about Markus' and Karl-Heinz' Testers recently.

After reading about the latest batches of LCR-TC1/TC2 containing counterfeit or clone MCUs, I tried not to head down the "Aliexpress Alley" - so I purchased a T7-Tester that is locally branded by german distributor Joy-It. I attached some pictures - as it seems, this still is "the real deal" on the inside?

This one was purchased from reichelt.de

[madires]

Yep, that should be a genuine ATmega328. If you want to run the m-firmware the settings are listed in the Clones file. IIRC, the STC15L104W of that model doesn't need to be reprogrammed.

[Specmaster]

I can thoroughly recommend one of these units with the case. I've had mine now for a number of years and is the same board as this uses, there are other slight variations of the eBay for sale, but I can't vouch for those, but this one has given my very good service and is certainly reasonably accurate, checking it against bigger 4 lead devices.

https://www.ebay.co.uk/itm/155087140184

[elecdonia]

…I purchased a T7-Tester that is locally branded by german distributor Joy-It. I attached some pictures - as it seems, this still is "the real deal" on the inside?
This one was purchased from reichelt.de

This unit should be perfect for upgrading to current OSHW firmware, either k- or m- style. To the best of my knowledge all ATmega328P chips in 28-pin DIP packages are genuine. And because it is mounted in a socket it will be very easy to change if you wish to do so.

Another good feature about this PC board is that it has pads for installing the standard 6-pin Atmel ISP programming header. This permits uploading firmware through an AVR-ISP programmer without removing the MCU from the PC board. I use “Arduino as ISP” for this.

[elecdonia]

I can thoroughly recommend one of these units with the case. I've had mine now for a number of years and is the same board as this uses, there are other slight variations of the eBay for sale, but I can't vouch for those, but this one has given my very good service and is certainly reasonably accurate, checking it against bigger 4 lead devices.
https://www.ebay.co.uk/itm/155087140184

There is one major issue with these Transistor Testers which have their MCU in a 32-pin TQFP package (8 pins on each of the 4 sides of the package).

     These days there are 3 totally different 32-pin TQFP package MCU chips which may appear in Transistor Testers:

Atmel ATmega328P   — this is the MCU specified by the original OSHW Transistor Tester project. However its price has increased from $3 USD to $9-10 USD, so the low-cost Chinese vendors stopped using it.

Logic Green LGT8F328P — This is a Chinese MCU which costs <$1 USD. It is said to be “somewhat” similar to the original Atmel AT328P. But unfortunately several of its pins have different functionality. Therefore a Transistor Tester containing LGT8F328P cannot easily have its MCU replaced by the Atmel ATmega328P. Also the LGT8F328P has substantially different internal features, which means existing OSHW firmware won’t work without considerable modification.

Aptchip APT32F172K8T6.  — Another Chinese MCU which costs <$1 USD. It has nothing at all in common with the original Atmel ATmega328P. The pinout is totally different. Also the internal MCU architecture is totally different.

Warning: Some of these $1 USD Chinese MCU chips have been deliberately mislabeled as “Atmel ATmega328P.”

More discussions about this are found here:
   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4613737/?topicseen#msg4613737
   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4610314/?topicseen#msg4610314
   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4600771/#msg4600771

[gipetto]

Hello folks,

I just found out about this thread on eevblog forums about Markus' and Karl-Heinz' Testers recently.

After reading about the latest batches of LCR-TC1/TC2 containing counterfeit or clone MCUs, I tried not to head down the "Aliexpress Alley" - so I purchased a T7-Tester that is locally branded by german distributor Joy-It. I attached some pictures - as it seems, this still is "the real deal" on the inside?

This one was purchased from reichelt.de

After you posted this i decided to buy it too, since i was in need of one and they took bank transfer as payment. my research says there's a minor issue with power with the stc chip on that model that can cause a higher standby drain as well as crashes. i'm not worried so much about the power drain since it is rechargeable.
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg3598639/#msg3598639

[Feliciano]

The high drain during standby was a major issue because the battery is small (and getting smaller). Nevertheless, it seems that part has already been solved by several of the manufacturers, if you want (or cannot migrate from) the chinese firmware.

[Specmaster]

I can thoroughly recommend one of these units with the case. I've had mine now for a number of years and is the same board as this uses, there are other slight variations of the eBay for sale, but I can't vouch for those, but this one has given my very good service and is certainly reasonably accurate, checking it against bigger 4 lead devices.
https://www.ebay.co.uk/itm/155087140184

There is one major issue with these Transistor Testers which have their MCU in a 32-pin TQFP package (8 pins on each of the 4 sides of the package).

     These days there are 3 totally different 32-pin TQFP package MCU chips which may appear in Transistor Testers:

Atmel ATmega328P   — this is the MCU specified by the original OSHW Transistor Tester project. However its price has increased from $3 USD to $9-10 USD, so the low-cost Chinese vendors stopped using it.

Logic Green LGT8F328P — This is a Chinese MCU which costs <$1 USD. It is said to be “somewhat” similar to the original Atmel AT328P. But unfortunately several of its pins have different functionality. Therefore a Transistor Tester containing LGT8F328P cannot easily have its MCU replaced by the Atmel ATmega328P. Also the LGT8F328P has substantially different internal features, which means existing OSHW firmware won’t work without considerable modification.

Aptchip APT32F172K8T6.  — Another Chinese MCU which costs <$1 USD. It has nothing at all in common with the original Atmel ATmega328P. The pinout is totally different. Also the internal MCU architecture is totally different.

Warning: Some of these $1 USD Chinese MCU chips have been deliberately mislabeled as “Atmel ATmega328P.”

More discussions about this are found here:
   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4613737/?topicseen#msg4613737
   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4610314/?topicseen#msg4610314
   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4600771/#msg4600771

I was not aware of this, however, if anything other than a capacitor or resistor failed, wouldn't it be better to replace the whole unit seeing as it is such a low cost unit, rather than run the gauntlet of facing a possible problem with fake chips? 

[elecdonia]

I was not aware of this, however, if anything other than a capacitor or resistor failed, wouldn't it be better to replace the whole unit seeing as it is such a low cost unit, rather than run the gauntlet of facing a possible problem with fake chips?

At the present time (March 2013) I can provide two recommendations worth considering. The choice depends on whether one wants a simple little device to toss into their toolbox for quick measurements (with limited accuracy), or whether they wish to learn more of “the details” of the Transistor Tester project with the intention of improving and customizing their device into an accurate and dependable bench instrument.

1)    For those who wish to get a functional Transistor Tester which won’t need any modification I specifically recommend the “LCR-TC2 V2.3E” model. Please expect to pay $30-40 USD for it. This  model contains a genuine Atmel ATmega324 MCU chip (44-pin TQFP square package).
Example:  https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4753835/?topicseen#msg4753835

2) For those who wish to modify/customize/improve their Transistor Tester I recommend the “kit-form” AY-AT GM328 “color” units which come as a bare PC board and a bag of parts. These units use the Atmel ATmega328P (28-pin DIP package).
Example:   https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4681222/?topicseen#msg4681222

3) Avoid purchasing “LCR style” units (plastic case with rechargeable battery inside) costing <$25 USD. Nearly all of these will contain cheap (<$1 USD) Chinese MCU chips. Most will be only partially functional. The OSHW Transistor Tester firmware does not currently support any of these $1 Chinese MCU chips.

[hapless]

I like DIP because of the ease of swapping out the chip. What would be the advantage of an ATmega324 over ATmega328 to pay a premium for a tester based on it?

1) Some of us want a Transistor Tester which comes in an attractive “toolbox-friendly” finished plastic case with a self-contained USB rechargeable battery, rather than an unenclosed PC board with a loose 9V battery dangling by its cable.

2) High-quality LCR-style units contain the ATmega324 MCU in a 44-pin TQFP package. In contrast, “cheap” LCR-style units have 32-pin MCU chips which probably aren’t the Atmel ATmega328P. However there aren’t yet any alternative “cheap” MCU chips which come in 44-pin TQFP packages. Therefore if a Transistor Tester contains a 44-pin TQFP MCU chip this indicates the MCU is likely to be an authentic Atmel ATmega324, rather than some dodgy $0.25 USD MCU with unknown architecture running poorly designed Chinese firmware which cannot be upgraded.

3) Transistor Testers with ATmega324 can be upgraded to ATmega644 to get twice as much flash (64k vs. 32k). This enables activating all of the advanced features offered by some versions of the open-source Transistor Tester software. The ATmega324 and ATmega644 have the same physical dimensions and pinout.

None of this is what I was asking. Looking to build, not buy. Need info.

[indman]

I like DIP because of the ease of swapping out the chip. What would be the advantage of an ATmega324 over ATmega328 to pay a premium for a tester based on it?

ATMega324 has more I/O ports than ATMega328 DIP. Therefore, you simply have more chanses and options for connecting peripheral sources for the tester. I don’t see any more advantages.

[madires]

None of this is what I was asking. Looking to build, not buy. Need info.

Please see https://github.com/kubi48/TransistorTester-documentation for Karl-Heinz' excellent documentation which includes schematics and a few hardware options. One benefit of an ATmega324 is that the additional pins allow you to assign things differently, making the use of hardware SPI possible (which is great for color displays). If you go for more features a 644 would be the better choice as the 328/324's flash is easily maxed out.

[hapless]

I see. Thanks.

A problem with a thread as huge as this is that even when you know what you're looking for, it's not always easy to find. It would be nice to have either the first post or a separate page (or web site?) that links to the current important stuff: Where the current repository is, where the most updated documentation is, where the different modifications are described (like how to wire up a display for hardware SPI for example).

A bit unrelated, I wanted to ask if you'd ever managed to solve the problem with LC add-on where it was counting too many pulses.

[Aldo22]

I know that many are unhappy with the tester that contains the APT32F172K8T6 (TC1 in my case).
But if you don't know anything about ATmega and firmware etc., it's not that bad for ~$10 including battery and case.
Despite the small battery, it has a really good endurance.
Once the problem with KAA range is solved (2K2 resistor) there is no reason to throw it away. Imo it's worth the money.

I randomly tested some components (cheap chinese stuff in a big bag). Here are the results.
Imho even the ESR values seem plausible.

Resistors:
680k -> 682k
220k -> 217k
51k -> 53k
3,3k -> 3.28k
100 -> 98.7

Capacitors:
6.8pF -> 6.2pF
470pF -> 520pF
3.3nF -> 3.5nF
220nF -> 240nF
470nF -> 504nF
1μF -> 0.974μF (ESR:4.1Ω)
2.5μF  -> 2.41μF (ESR:4.8Ω)
10μF -> 9.78 (ESR:0.98Ω)
22μF  -> 24.6μF (ESR:1.5Ω)
33μF  -> 32.1μF (ESR 0.8Ω)
47μF  -> 49μF (ESR:0.5Ω)
220μF  -> 228μF (ESR:0.2Ω)
470μF  -> 420μF (ESR:0.13Ω) (Aneng 8080 shows also 420μF).

Diodes:
1N4148 -> Uf=708mV C=2pf Ir=11na
1N4007 -> Uf=703mV C=9pf Ir=8na
FR107 -> Uf=666mV C=10pf Ir=10na

Zener:
3.6V -> 3.6V
5.1V -> 5.1V
12V -> 12.2V

Transistors:
A42:    NPN hFE=45  Ube=609mV Ic=5.9mA
BC547B: NPN hFE=344 Ube=774mV Ic=5.9mA
BC547C: NPN hFE=562 Ube=813mV Ic=5.9mA
C1815 : NPN hFE=382 Ube=773mV Ic=5.9mA
C8050:  NPN hFE=138 Ube=695mV Ic=5.8mA
C945:   NPN hFE=362 Ube=768mV Ic=5.9mA
S9013:  NPN hFE=151 Ube=675mV Ic=5.8mA
S9014:  NPN hFE=375 Ube=770mV Ic=5.9mA
S9018:  NPN hFE=71  Ube=735mV Ic=0.0mA
2N3904: NPN hFE=214 Ube=719mV Ic=5.9mA
2N2222: NPN hFE=289 Ube=717mV Ic=5.9mA
2N3904: NPN hFE=211 Ube=718mV Ic=5.9mA
2N5551: NPN hFE=154 Ube=681mV Ic=5.9mA

A93:    PNP hFE=116 Ube=729mV Ic=6.0mA
A733:   PNP hFE=385 Ube=890mV Ic=6.0mA
A1015:  PNP hFE=358 Ube=884mV Ic=6.0mA
2N5401: PNP hFE=162 Ube=761mV Ic=6.0mA
2N3906: PNP hFE=210 Ube=838mV Ic=5.9mA
S9012:  PNP hFE=184 Ube=776mV Ic=6.0mA
S9015:  PNP hFE=390 Ube=889mV Ic=6.0mA
S8550:  PNP hFE=345 Ube=868mV Ic=5.9mA

It definitely helps to put the components in the right drawer. 

[Specmaster]

I agree, those results are very similar to my findings and are certainly good enough to work with in the restoration / repair of other equipment.