$20 LCR ESR Transistor checker project

[BradC]

I just want to say a serious thanks to everyone in this thread (with a special shout to madires).

I have two of these:
http://www.ebay.com/itm/M328-LCD-12864-DIY-Transistor-Tester-Kit-Diode-Triode-Capacitance-LCR-ESR-Meter/161913228003?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I bought two because 5 minutes into my use of the first one I put it across a cap that still had ~50V in it and popped the uC. I ordered another kit and just swapped the uC in.

Yesterday I bought a couple of new 328P chips, bodged an ICSP header onto my built unit, grabbed the latest source tree, read the instructions, and built & loaded the firmware into the unit. I already had a $2 e-bay USB-ASP clone lying around. It worked first try. The documentation is good, the build configuration is good and man if it wasn't dead easy. So thanks madires!

On another note, this kit comes with 0.1% measure resistors, a ht7550 LDO and a TL431 (of some sort). I have a 6.5 digit meter, and the TL431 has been steady for the 6 months I've had/used the device now (well within its specified 100ppm/C. Certainly accurate enough for this use), so if you have the means to measure and put the correct UREF_25 value in, this kit is not too bad out of the box.

This is my first experiment with the AVR, and it was almost easy enough to make me think about using them in lieu of PICs or Propellers in some prototype applications.

[ez24]

What do you guys think about this one that uses a 18650

https://www.aliexpress.com/item/Free-shipping-New-3-7V-version-of-inductor-capacitor-ESR-meter-DIY-MG328-multifunction-transistor-tester/32613345424.html?spm=2114.search0104.3.119.Uvlbif&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10065_10151_10068_10130_5490020_10307_10137_10060_10155_10154_10056_10055_10054_5470020_10059_100031_10099_5460020_10103_10102_10052_10053_10142_10107_10050_10051_10324_10325_5380020_10326_10084_10083_10080_10082_10081_10178_10110_10111_10112_10113_10114_10312_10313_10314_10078_10079_10073_5550011-10102,searchweb201603_21,ppcSwitch_3&btsid=e424fa78-3354-41f1-88b8-73f37e871fb7&algo_expid=dbdf11c9-75f2-427c-b5b7-94ce3a31a5f3-18&algo_pvid=dbdf11c9-75f2-427c-b5b7-94ce3a31a5f3


(jezzz what an URL)

I have many 18650s and no 9v batteries

thanks

[upsss]

This tester DOESN'T use an 18650, it uses an 14500, also a lithium Ion which is the size of a AA and not as popular as the 18650.

[mauroh]

There are so many hardware variants based on the exact same core schematic and before everyone rush to buy the variant that Dave reviewed, I think it is better to evaluate which will better fit your needs.

The main difference I considered are:

Thru hole            vs   smt components        If you forget to discharge a capacitor before testing it the THT version can be fixed quickly
Assembled          vs   DIY Kit                      a DIY kit shouldn't be an issue in this forum
With push button vs  with rotary encoder    whith the encoder it is easier to navigate in the menu to select specific measurements options (opto, IR, Servo...)
With case            vs  without case              I like the case one

For instance my personal preference is the one that is called Hiland DIY M12864 Kit at Banggood, because it is THT, it has a nice case and it is faster than the color display variant.
I modifyed it to have:
External input voltage
ICSP connector
UART for measurement logging also with Bluetooth....

Mauro

PS: I posted the same message on the thread related to the video posted by Dave, but I think this should belong here.
Link to the other thread
https://www.eevblog.com/forum/blog/eevblog-1020-is-a-$7-lcr-component-tester-any-good/msg1296703/#msg1296703
Link to the enclosures-and-mods thread
https://www.eevblog.com/forum/testgear/show-us-your-$20-transistor-tester-enclosures-and-mods/
Link to the Mailbag thread where also this tester is discussed
https://www.eevblog.com/forum/blog/eevblog-1019-mailbag-94564/

[Giox040]

Can anyone recommend me a DC-DC step up from 5-9V up to about 25V for Z-Diode test to buy on ebay?

A good DC/DC converter would be MEA1D0515SC from muRata. I recommend to power it by a separate LDO with proper decoupling. Please see the ATmega 644 schematic in Karl-Heinz's documentation.

Hi Madiras!
Thanks for the quick reply.
I have seen that the MEA1D0515SC is quite expensive.
I've seen some cheaper converters on eBay, such as the link below here could not be enough?

http://www.ebay.it/itm/DC-DC-Step-up-Boost-Converter-3-3V-5V-9V-12V-2A-Adjustable-Power-Supply-Module-/322449827696?hash=item4b1381e770:g:gT8AAOSwsS1ZjQ46

[madires]

I can't say anything about that boost converter. Buy and try

[upsss]

Thanks for the quick reply.
I have seen that the MEA1D0515SC is quite expensive.
I've seen some cheaper converters on eBay, such as the link below here could not be enough?

http://www.ebay.it/itm/DC-DC-Step-up-Boost-Converter-3-3V-5V-9V-12V-2A-Adjustable-Power-Supply-Module-/322449827696?hash=item4b1381e770:g:gT8AAOSwsS1ZjQ46

I have used a similar one, they are adjustable up to 28V and it works fine.  You can find them on eBay or Aliexpress for less than $1.

[jakeisprobably]

...or if you want to go cheap and dirty just grab an old car type phone charger as they almost always contain a MC34063, and build a boost converter for free by simply reconfiguring the parts layout and adding a junk bin trimmer pot for one of the voltage divider feedback resistors. Almost any simple peak mode SMPS controller can be reconfigured from the typical buck to a boost circuit extremely easily.
   However the professional modules like Madires suggested are much much higher quality and less noisy as they are designed to create +/-15 volt rails for powering things like op amps.
Over simplified 34063 circuit calculator
Onsemi SMPS Reference
MC34063 pin by pin description
Onsemi MC34063 Design Spreadsheet -Excel file

[ez24]

This tester DOESN'T use an 18650, it uses an 14500, also a lithium Ion which is the size of a AA and not as popular as the 18650.

Yikes   

[jakeisprobably]

What do you guys think about this one that uses a 18650

If I wanted to get a Lithium powered unit I'd get the "T6."
Like this:
http://www.ebay.com/itm/232333734207
That's the evolution of the one that Dave was sent. Unfortunately the screen is color, but you get a bunch of extra circuits like infrared and zener threshold if I'm not mistaken. The unit that Mauroh suggested has a nice case with a monochrome screen, but all of these have surface mount MCU's.
 A quick scan through my files and it looks like the "LCR-T6/TC" was mentioned on pages 103, 112, 128, 146, and 150. Page 150 contains a video that unintentionally shows the color TFT screen clear delay. I believe that is the speed with the 8MHz Xtal, so a 16MHz and recompiled firmware should half that delay. I'm not sure of the difference between the T6/TC but they look similar at a glance.
 I believe the one Dave has is the "LCR-T4" but I could be mistaken. The T4 Schematic is on page 119, and one of the times it was discussed a good bit was on page 38.

Edit: here's a video that shows screen clear delay, and IR remote (no affiliation)
https://youtu.be/8Fk09QxJrh8

[ez24]

7.) I'm still very confused, and I'm starting to feel impatient with you. What is the latest cheap clone I should look for?
 The 'names' of clones are non-existent. The latest mass produced version (2017) comes with a red PCB that is often incorrectly called a M12864 by sellers. The variation that is sold with a frequency counter and Square Wave PWM output is usually considered the 'latest pretty version.' This version reliably comes equipped with an ATmega328 and is already configured with most project accessory options. Forum members often call it "AY-AT" because this has been printed across a few variations.

Searching Aliexpress on M12864 brings up kits.   Searching on AY-AT does not come up.

Does anyone know of a variation that is sold with a frequency counter and Square Wave PWM output is usually considered the 'latest pretty version.   That is NOT a kit?

thanks

[all_repair]

What do you guys think about this one that uses a 18650

If I wanted to get a Lithium powered unit I'd get the "T6."
Like this:
http://www.ebay.com/itm/232333734207
That's the evolution of the one that Dave was sent. Unfortunately the screen is color, but you get a bunch of extra circuits like infrared and zener threshold if I'm not mistaken. The unit that Mauroh suggested has a nice case with a monochrome screen, but all of these have surface mount ...

My problem with T6 and the rest of Tx (except early T) is they are surface mount, and the LCD are soldered to PCB.  To reprogram, either you have to desolder the LCD ribbon cables, or to desolder the chip.  after the reprogramming, soldering them back. 

[stj]

the problem with socketed chips is the contact resistance can change over time.

smd chips are best - fit a programming header.

[texaspyro]

the problem with socketed chips is the contact resistance can change over time.

smd chips are best - fit a programming header.

No, they are not!  These testers have a known, all to common, failure mode of the chip blowing if you connect a charged capacitor.   The hassles of having to do SMD rework to replace the chip far outweighs potential issues of (minuscule) changes in contact resistance. 

At 0.1% tolerance the 680 ohm resistance is  within +/- 0.68 ohms.  I seriously doubt even a crappy IC socket would change that much... I put screw machine contact sockets in mine.  I also have a few different processors configured with different options and occasionally swap them out... no need to dig out the programmer.  Using SMD processors for these devices is just not the best idea.

[jshonw]

7.) I'm still very confused, and I'm starting to feel impatient with you. What is the latest cheap clone I should look for?
 The 'names' of clones are non-existent. The latest mass produced version (2017) comes with a red PCB that is often incorrectly called a M12864 by sellers. The variation that is sold with a frequency counter and Square Wave PWM output is usually considered the 'latest pretty version.' This version reliably comes equipped with an ATmega328 and is already configured with most project accessory options. Forum members often call it "AY-AT" because this has been printed across a few variations.

Searching Aliexpress on M12864 brings up kits.   Searching on AY-AT does not come up.

Does anyone know of a variation that is sold with a frequency counter and Square Wave PWM output is usually considered the 'latest pretty version.   That is NOT a kit?

thanks

Try searching  for GM328 on ebay and you should see something like xxxxAY-AT next to the encoder on the board in one of the pictures. 

Something like this one.   Not sure if it contains 0.1% resistors.  Can somebody confirm?
http://www.ebay.com/itm/2017-TFT-GM328-Transistor-Tester-Diode-LCR-ESR-meter-PWM-Square-wave-Generator/172557508334?var=471403196090&_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D41375%26meid%3D587faf2ced2c4a1986707a5cb50c443a%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D112489435576&_trksid=p2047675.c100005.m1851

[stj]

the problem with socketed chips is the contact resistance can change over time.

smd chips are best - fit a programming header.

No, they are not!  These testers have a known, all to common, failure mode of the chip blowing if you connect a charged capacitor.

so dont - discharge it first. 

btw, i can swap-out a QTFP package faster than you can swap a chip in a dil socket!

[texaspyro]

btw, i can swap-out a QTFP package faster than you can swap a chip in a dil socket!

NO, you can't...  I'll have the chip swapped before your soldering system even warms up.  Then you have to clean up and solder 32 pins.   I just swapped a tester processor chip in under a minute.

And probably 99% of the people buying these things have never soldered a SMD device in their lives, much less removed a 32 pin CPU chip.  And they are also the types that are rather prone to not discharging their caps.

[stj]

a min - a whole 60 seconds??

you obviously never watched a pro with a hot-air station, a pair of tweezers and a bottle of flux.
if the station was already on, i could change it twice in that time!

[jakeisprobably]

Does anyone know of a variation that is sold with a frequency counter and Square Wave PWM output is usually considered the 'latest pretty version.   That is NOT a kit?

AY-AT is what "we call it on the forum."
 To sellers they are all GM328's or Hiland KKmoon thingy madoos. I've tried to to figure out some kind of logic to their naming convention but if you search long enough you will find all of clones called the same things in different places. The names will just limit the sellers you find while searching.
   The easiest way to search is by physical features. If you want almost all AY-AT variations search "Tester PWM" that is an extremely specific and unique term.
Or here's a seller with assembled, kits, or case options in one listing.
http://www.ebay.com/itm/112489435576

If you go the AY-AT route be sure to check this post out first.
Edit /\
         |
Correct link

[ez24]

Or here's a seller with assembled, kits, or case options in one listing.
http://www.ebay.com/itm/112489435576

Thanks  I ordered one assembled with the case for $18

[jakeisprobably]

I just have to say... it might be worth it to pay $14 for this $7 tester just to be like Dave:

Such a great relevant contextual image right?

[bitseeker]

At least that "electrician" isn't trying to hook up the tester to a live, high-energy panel.

[mauroh]

Or here's a seller with assembled, kits, or case options in one listing.
http://www.ebay.com/itm/112489435576

Thanks  I ordered one assembled with the case for $18

What do you guys think about this one that uses a 18650

If I wanted to get a Lithium powered unit I'd get the "T6."
Like this:
http://www.ebay.com/itm/232333734207
That's the evolution of the one that Dave was sent. Unfortunately the screen is color, but you get a bunch of extra circuits like infrared and zener threshold if I'm not mistaken. The unit that Mauroh suggested has a nice case with a monochrome screen, but all of these have surface mount ...

My problem with T6 and the rest of Tx (except early T) is they are surface mount, and the LCD are soldered to PCB.  To reprogram, either you have to desolder the LCD ribbon cables, or to desolder the chip.  after the reprogramming, soldering them back. 

Well done guys !!

The point of my message is to encourage all the viewers of the Dave's review to evaluate some of the variants and find the best fit for their needs.
My choice was the best for me the day I evaluate it.

As for me, texaspyro and stj are both right :
If you are good with smt or you don't know how to solder (es. a breadboard man...) go for the smt variant if it will blow up you will fix it (in 24 seconds ) or buy another one for 7$
Is there an smt variant with rotary encoder, case and color display already assembled?
I think we need to add a buyers guide in the documentation, something like -> if you want it with the case, this are the current options (or 3d print it), if you want it with the lithium barrery, if you want it with the rotary encoder...

Mauro

[upsss]

Is there an smt variant with rotary encoder, case and color display already assembled?

Here it is, it looks like there are a couple of variation of it too.  All of them seem to have a black PCB as opposed to the red, green of yellow PCB.

http://www.ebay.com/itm/LCD-GM328A-Transistor-Tester-Diode-ESR-Meter-PWM-Square-Wave-Generato-Practical-/132281636619?epid=942275376&hash=item1ecc99970b:g:zU8AAOSwtGlZNhE2

[mauroh]

Thanks for the answer , but It was a rhetorical question, since it is also the one suggested by jakeisprobably and linked in my own post (ok, my english is terrible...)

Mauro