$20 LCR ESR Transistor checker project

[madires]

I have a question about the "Button" connection for the Zener expansion option. Should the gate of T4 be tied directly to PD7, or is there supposed to be a button switch between the two, or something else?

Yes, please connect the gate of T4 directly to PD7.

[amtpdb]

knowing what you all know about the testers available on e----, if you had your choice on which one to buy and it can be updated and will work, which one would you buy?
I would appreciate a particular one and not just anyone will work. I don't want to guess and get the wrong one or one that does not work or can't be updated.

Thanks
Don

[madires]

knowing what you all know about the testers available on e----, if you had your choice on which one to buy and it can be updated and will work, which one would you buy?
I would appreciate a particular one and not just anyone will work. I don't want to guess and get the wrong one or one that does not work or can't be updated.

Basically any clone with an ATmega328 and a standard 2x16 LCD display will work fine. If you're looking for a particular recommendation please read a few posts back and you'll find several links, pictures and comments on specific models.

PS: Firmware 1.14m was released a few days ago with some minor improvements, a fix for the resistor issue (1k5-3k) and the frequency counter option. There's also an adapter PCB (DIY-style, Eagle files) for the rotary encoder and frequeny counter input stage in the hardware sub-directory in the SVN.

[JoeO]

The only thing I would recommend is that you purchase one with a DIP socketed 328.  That way you can buy a spare 328, program it up to the latest level and swap it in to test it.  If the new 328 does not work, just revert back to the old 328.

[AlessandroAU]

Does anyone have any experience with these variations that are popping up on ebay?

I don't really have any reference standard to compare it to but it seems to measure and identify any passive I can throw at it.

[andrewwong2000]

Hey Alessandro

That's the "LCR T3" design.

Any chance you can read the flash and EEPROM and email to me ?

These ones use an older version of the firmware but I'm trying to figure out that display so it can be upgradeable.

That one you have has a 6pin ISP pin pad but it's reversed on the component side



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[v0yAgEr]

Hi everyone,
Can someone please confirm that mk-168 unit is indeed m328 and supports firmware upgrades? I really want to buy one, but I want to make sure I got that covered first.
Thanks!

[radioFlash]

Hi everyone,
Can someone please confirm that mk-168 unit is indeed m328 and supports firmware upgrades? I really want to buy one, but I want to make sure I got that covered first.
Thanks!

The video doesn't show what's under the LCD, so you can't tell from the video alone. The board also seems to be single sided--most singled sided versions of the board don't seem to have a programming header. Since it has "168" in the name, my guess is it uses the ATmega168 rather than Atmega328. I would look for another variant.

[v0yAgEr]

Hi everyone,
Can someone please confirm that mk-168 unit is indeed m328 and supports firmware upgrades? I really want to buy one, but I want to make sure I got that covered first.
Thanks!

The video doesn't show what's under the LCD, so you can't tell from the video alone. The board also seems to be single sided--most singled sided versions of the board don't seem to have a programming header. Since it has "168" in the name, my guess is it uses the ATmega168 rather than Atmega328. I would look for another variant.

Thanks for the reply!
If not that unit, then Im looking for something like this:
Flashable m328, and would really like to have a model with probes for in-circuit testings. Any recommendations?

[omgfire]

Hi everyone,
Can someone please confirm that mk-168 unit is indeed m328 and supports firmware upgrades? I really want to buy one, but I want to make sure I got that covered first.
Thanks!

https://www.eevblog.com/forum/beginners/what's-your-favorite-little-inexpensive-esr-etc-tester/msg470124/#msg470124

[v0yAgEr]

Great! Ordering now...

[texaspyro]

I bought a couple of these testers... the fish8840 version with the nice graphics LCD.  Yeah,  probably not as upgrade friendly as the character LCD units,  but I'm a sucker for pretty pictures (but it doesn't draw pictures for SCR's and TRIACs).  They work very well.  So far it has properly identified everything I've thrown at it (except some big SCRs and TRIACs that it can't drive the gate hard enough.  Component values measurements are in the .2% accuracy range.  All in all,  the best 20 bucks you can spend...

Both units had a problem where they would not turn on with a fresh battery installed...  the screen would just flash once and then go off.  A few of simple fixes for this...  use a used battery,  a low ohm resistor in series with the battery (2 ohms worked for me), or replace the 78L05 regulator with an LM2936 ultra low power LDO regulator... same pinouts as the 78L05 and it also drops a few mA from the operating current...  that was my ultimate solution to the problem.

The other problem is the battery voltage divider is connected permanently across the battery.  The OFF current is 180 uA...  will drain the battery in a couple of months.  I moved the input of the voltage divider resistors from the battery connection to the input of the voltage regulator (i.e. after the power-switch transistor).  This reduces the OFF current to well below 1 micro-amp.

One really useful addition to the firmware would be the ability to measure the Rds ON resistance of FETs...

[timb]

Great! Ordering now...

I just ordered one of these myself from Amazon after seeing the teardown. Which firmware should I use on this? There seems to be so many versions of these and the firmware, I’m a little confused. Edit: After looking around, since this uses an AT328P and standard 20x2 LCD, I guess the m328 build is what I’m after?

Another question, after watching the YouTube video you linked, this seems to show the battery voltage on startup. Is there a regulator onboard? I’d like to power this from a small LiPo battery with a tiny LiPo -> 5V boost converter. Is that battery test feature part of the “official” firmware?

[Wh1sper]

Does anyone have any experience with these variations that are popping up on ebay?

I don't really have any reference standard to compare it to but it seems to measure and identify any passive I can throw at it.

I do own this one without case.
It measure quite well not so exact like my other selfmade one. I guess the resictors are not so high quality ones.

I wished there were some more information about the LCD Hardware .. Controller.. etc.
Downside is the software isn't open any more :-(

[MrJohnnny]

Downside is the software isn't open any more :-(

You mean Transistor Tester is not an open source anymore?

[madires]

Downside is the software isn't open any more :-(

You mean Transistor Tester is not an open source anymore?

No worries! The official Transistor Tester firmware (k and m version) is open source!!! Unfortunately some clone vendors modify the source and claim ownership while violating the copyright of the original authors. It doesn't make much sense to try stopping them, because that would require a lot of money for lawyers. Therefore my advice is to buy only hardware compatible clones, since those can be upgraded to the current firmware version. If you buy a clone with a modified hardware/firmware, you might never get any update from the vendor. And a self-made tester is best one anyway

PS: The next m-firmware version will have a squarewave signal generator (up to 2MHz for 8MHz MCU clock) operated by the rotary encoder supporting dynamic turning velocity.

[Wh1sper]

Downside is the software isn't open any more :-(

You mean Transistor Tester is not an open source anymore?

No no, only the Chinese modifier don't publish their modifications.
That's what a meant.
What a dissipation of human brain power.
Imagine those Chinese guys (or girls?) would contribute their improvements and / or modifications.......

[timb]

So, my MK-168 unit came in today. The build quality is pretty nice overall; it uses an AT328P in a socket, with no footprint for an ICSP header. Looking at the board it seems to have been designed late last year. Some markings on the board: M168_V2.20, M8/168/328_9V_V2.20, 2013.10.16, EZM Electronics Studio.

The one real problem I found was C3 and R11 only being soldered on one side. (Looks like the missing solder was on the ground side, which even took my iron a few seconds to heat up, so I suspect whatever worker made this board didn’t have their iron hot enough.)

Another thing I noticed was the lack of a Zener diode, which I thought was required for a voltage reference? The other thing of note is SMD capacitors C1 (missing), C6, C7 and C8 on the back. There’s plenty of board space on the front, so I thought that was a weird decision. The last oddity is what appears to be a bodge resistor connecting pin 2 of the ATmega to VCC.

The package came with what you’d expect, the unit in a case, three test leads and a ZIF/SMD adapter. In addition to the standards the seller also threw in a power cable for rigging up your own external supply and an extra power connector (not sure what’s up with that).

Here’s full resolution versions of the attached pictures if you want to examine the front or back of the board in detail: http://img.timb.us/index.php?f=TrannyTaster

[dentaku]

So, my MK-168 unit came in today. The build quality is pretty nice overall; it uses an AT328P in a socket, with no footprint for an ICSP header. Looking at the board it seems to have been designed late last year. Some markings on the board: M168_V2.20, M8/168/328_9V_V2.20, 2013.10.16, EZM Electronics Studio.

The one real problem I found was C3 and R11 only being soldered on one side. (Looks like the missing solder was on the ground side, which even took my iron a few seconds to heat up, so I suspect whatever worker made this board didn’t have their iron hot enough.)

Another thing I noticed was the lack of a Zener diode, which I thought was required for a voltage reference? The other thing of note is SMD capacitors C1 (missing), C6, C7 and C8 on the back. There’s plenty of board space on the front, so I thought that was a weird decision. The last oddity is what appears to be a bodge resistor connecting pin 2 of the ATmega to VCC.

The package came with what you’d expect, the unit in a case, three test leads and a ZIF/SMD adapter. In addition to the standards the seller also threw in a power cable for rigging up your own external supply and an extra power connector (not sure what’s up with that).

I have exactly the same one with all the same markings. I just opened it up to make sure it's soldered right and I don't have the bodge resistor on pin 2, C1 is unpopulated and C3 and R11 are soldered just fine and I see no zener.

I'm guessing the jack came with the power cord so they just included it. I've never used it with a battery before so it's nice to be able to plug it in.

I like the ZIF adapter for testing large amounts of capacitors because it's much quicker and less fiddly than mini grabbers.

[timb]

After doing some reading, it seems C1 being unpopulated is correct. Yeah, I love the ZIF socket. Between that and the SMD pads (I sorted through a drawer of random FETs tonight, so fast) I think using the leads will be rare.

The ZIF doesn't scream quality to me, but it's by no means bad either. (I've seen much worse on much more expensive gear.) I figure I can always buy a new socket if it breaks.


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[RLSprouse]

Another thing I noticed was the lack of a Zener diode, which I thought was required for a voltage reference? The other thing of note is SMD capacitors C1 (missing), C6, C7 and C8 on the back. There’s plenty of board space on the front, so I thought that was a weird decision. The last oddity is what appears to be a bodge resistor connecting pin 2 of the ATmega to VCC.

I assume the "bodge resistor" you refer to is the little surface mount package.  I believe that is on pin 27, not pin 2, if I remember how to count pins on a DIP.

[andrewwong2000]

Thought Id share..

I built 3 of Frenchie's Transistor Tester boards to practice my first go at 0603 SMD soldering, plus have a bit of fun.

Great little board that fits neatly behind a LCD display

Thanks to Markus, Karl Heinz and Frenchie !


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[con-f-use]

Why is there an Atmega88 and not a 328 on Frenchies board? And which resistors should be 0.1% ones? Why use 0.1% ones in the first place when the software calibrates itself and there's a voltage reference on board?

[radioFlash]

R1-R6 on the schematic should be .1%. They are the 680 and 470k resistors.


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[con-f-use]

But why, if the tester calibrates against a precision voltage reference?