$20 LCR ESR Transistor checker project

[Per Hansson]

Per Hansson,What operating voltage is present on this diode in the circuit?

The output from the transformer is 50v p-p at ca 100kHz, see attached screenshot.

[indman]

The operating voltage exceeds the test voltage by 10 times, so it has been repeatedly repeated in this and other topics that this tester cannot provide a 100% probability of detecting all faults.

[Yuriy_K]

Yuriy_K: I desoldered a working Rohm 1SR159-200 diode now but unfortunately it measures almost identical to the bad one:
Uf=545mV
10pF - 3.5pF @ 0 - 5V
Ir=0.20µA

I thought it could be a nice addition to measure the reverse recovery speed (trr) since this was a pretty tricky failure mode, but if the ADC is too slow then that is not possible of course...

I made a comparison of similar characteristics of US1M and 1SR159-200. Compare for yourself, I can’t understand where Ir=0.18µA  comes from at 5v. Probably problems with the diode, it is a pity that there is no unused diode to compare with the used ones.

[Per Hansson]

I made a comparison of similar characteristics of US1M and 1SR159-200. Compare for yourself, I can’t understand where Ir=0.18µA  comes from at 5v. Probably problems with the diode, it is a pity that there is no unused diode to compare with the used ones.

Notice how there is very little difference of reverse current at 200v vs the minimum the datahseet shows at 50v.
So if we extrapolate down to 5v it is easy to see how the reverse current value could still be valid.

The operating voltage exceeds the test voltage by 10 times, so it has been repeatedly repeated in this and other topics that this tester cannot provide a 100% probability of detecting all faults.

Sure, but it still provides relevant data, I'm sure it could test reverse recovery time too even at that low voltage.
But as madires says if the speed of the ADC is not enough that will limit the lowest trr value we can see.
And just to provide a different way to visualize it:
Diotec ES1D in-circuit output voltage: 17.87v
Rohm 1SR159-200 in-circuit output voltage: 17.83v
Diotec UF4007 in-circuit output voltage: 17.30v
Bad Rohm 1SR159-200 in-circuit output voltage: 14.4v

[9voltbrain]

Can anyone chime in on the differences between the LCR-T7 and LCR-T4? I'm mostly interested in getting some ballpark measurements on the inductors I have lying around here. As long as I get +/- 20uH I'm happy. I don't want to get the LCR-T7 because of the built in rechargeable battery. It's just annoying to me having to keep it charged and dealing with it going bad eventually. Do you have to recalibrate the T4 every time you take the 9v battery out?

There is also another meter available from where I usually buy stuff called M162, but I can't find any info on it. Anyone tried it? It's like 3x the price of the other ones. Picture below.

[Feliciano]

Have you looked at indman's table of ctester clones?

[elecdonia]

There is also another meter available from where I usually buy stuff called M162, but I can't find any info on it. Anyone tried it? It's like 3x the price of the other ones. Picture below.

That is a gorgeous display. Someone with talent designed it and wrote the code for it.

Regarding testing small inductors, have you considered the LC100-A?
It measures L and C only (nothing else). I’ve had one for years. It is an excellent companion for a Transistor Tester because it uses a totally different measurement process. I found that the LC100-A does a great job measuring L <10uH and C <50pF. Here’s a topic that discusses them:

https://www.eevblog.com/forum/testgear/lc100-a-a-precise-lc-meter-for-3-75$/msg4599424/#msg4599424

[Messtechniker]

The M162 is not a transistor checker.
You might want to go here:
https://www.eevblog.com/forum/testgear/new-jyetech-m162-lcr-meter-(april-2022)/msg4136254/#msg4136254

[Yuriy_K]

As long as I get +/- 20uH I'm happy.
...
Do you have to recalibrate the T4 every time you take the 9v battery out?

Three years ago I made a firmware for T4 for another forum. In it, to measure small inductances and capacitances, it is necessary to replace the crystal with 16 MHz. Since then, much of the software has changed and expanded. In the archive, the changes are in New, but this firmware is not tested, I do not have T4.
The calibration is retained when the battery is replaced.

Examples of measuring small inductances are in my posts.

[hojnikb]

hello; new here with these whole cheap LCR tester... Which one should one buy these days? There seems to be lots of different versions available (like TC1, TC2, T7 etc)....

Is there a list of all these clones and pros/cons of each one? 

[hojnikb]

hello; new here with these cheap LCR testers... Which should one buy these days? There seems to be lots of different versions available (like TC1, TC2, T7 etc)....

Is there a list of all these clones and pros/cons of each one? 

[madires]

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

[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