$20 LCR ESR Transistor checker project

[pepe10000]

It would be interesting to know if you can try powering the encoder with 3.3v instead of 5v and hopefully that will fix your last problem.  Simply move the white wire that goes to the input of your 3.3v regulator to the output of the regulator.

Hi, I connected the rotary encoder to 3.3v to get out of doubt and the behavior has been the same.

When you rotate super-fast the meter will restart.

As I said before is not a serious problem since it is not necessary to rotate the encoder so fast.

A greeting.

[stj]

maybe it's glitching the power rail.

[ja421]

It seems that they are selling the 'AY-AT color kit' now with extra functions added in the firmware.

I ordered this one, it arrived w/ incorrect & missing parts; as well as a blank atmega328p and no download for firmware...  (I ended up using M firmware & updated to 16mhz)

[upsss]

It would be interesting to know if you can try powering the encoder with 3.3v instead of 5v and hopefully that will fix your last problem.  Simply move the white wire that goes to the input of your 3.3v regulator to the output of the regulator.

Hi, I connected the rotary encoder to 3.3v to get out of doubt and the behavior has been the same.

When you rotate super-fast the meter will restart.

As I said before is not a serious problem since it is not necessary to rotate the encoder so fast.

A greeting.

Hi again,  I looked carefully at your board wiring and I see that you have external pool up resistors on pin 32 (PD2) and pin 2 (PD4) both tied to the 5v supply. 

I don't understand why you have the poll ups tied to the 5v and not to your 3.3v supply.  If you are going to have these external pull up tied to your 5v, you might as well use the processor's internal pull ups and use the CFLAGS + = -DLCD_SPI_OPEN_COL command.  The purpose of this command I think is so you can disable the internal pull ups and provide external pull ups exactly us as you did but not tied them to the 5v. 

In your case, since you powered the LCD display from your 3.3v regulator, you would want all inputs to the LCD display including the encoder swing to 3.3v only and not to 5v which is the real reason for all the problems that we are experiencing.

You did mentioned that once you disabled the internal pull ups with the # CFLAGS + = -DLCD_SPI_OPEN_COL command, that fixed most of your problems.  My only explanation for that is that probably the processor wasn't able to sink the current from both pull up the external and internal and that is why you had to disable the internal pulls ups.

[Willem52]

It seems that they are selling the 'AY-AT color kit' now with extra functions added in the firmware.

I ordered this one, it arrived w/ incorrect & missing parts; as well as a blank atmega328p and no download for firmware...  (I ended up using M firmware & updated to 16mhz)

That seems to happen with some sellers, I had it too, but the seller sent me a programmed chip for free. As it should be.

>>> In my post I was referring to those new built-in firmware menu options.

[pepe10000]

I don't understand why you have the poll ups tied to the 5v and not to your 3.3v supply.

They are at 5v because so advises Karl-Heinz here:

https://www.mikrocontroller.net/topic/248078?page=single#4541666

You did mentioned that once you disabled the internal pull ups with the # CFLAGS + = -DLCD_SPI_OPEN_COL command, that fixed most of your problems.

If you have solved the spin problems, but that command does not disable PULL-UP, I think it only controls communications with the LCD.

To disable PULL-UP, use the command "CFLAGS + = -DPULLUP_DISABLE" and it is necessary to change it if you do not have these resistors as the screen would be blank using the firmware located at "https://www.mikrocontroller.net / Svnbrowser / transistortester / Software / trunk / mega328_T3_T4_st7565 /".

A greeting.

[madcat]

Hi all,
i just bought this "AY-AT" type tester, still have no chance to assembly it yet.
gladly, it came with those SMD parts nicely soldered in place already.

what i read here, there's some users reported that they received wrong pieces of resistors (between 3.3k and 33k).
here what i received are : 2pcs of 3.3k  and 1pc of 33k (confirmed with DMM).
based at PCB labels, they supposed to be correct, don't they?


btw, i have listed all of the components i received, if there's anyone interested, i will post it here.

[Willem52]

See the long description of the 'AY-AT color kit' tester here:
https://www.aliexpress.com/item/2016-DIY-KITS-ATMEAG328P-M328-Transistor-Tester-LCR-Diode-Capacitance-ESR-meter-PWM-Square-wave-Signal/32732193545.html?spm=2114.13010308.0.0.duTKII

The components are listed there as well.
and see the attachments of:
https://www.eevblog.com/forum/testgear/]$20-lcr-esr-transistor-checker-project/msg1007286/#msg1007286

[madcat]

thank you very much Willem52, those links are very informative.
i think the "transistor tester assembly instruction" pdf needs a little correction in the components table.
where 3.3k resistors marked R12, R7, but in number of component column listed as "1". 

[Willem52]

Well, the information now available is more than we can expect from most of the Chinese vendors 😎

[edavid]

Here's a scan I made of the AY-AT PCB... in the image, the bottom side is flipped, which I find convenient when probing from the top side.

[upsss]

Hi, I need some help.  I added the required hardware for testing Zener diodes on a T3-T4 tester.  What exactly do I have to change in the Make file to have the firmware work?  I am using firmware ver. 698.

[madires]

WITH_VEXT
EXT_NUMERATOR
EXT_DENOMINATOR

[upsss]

Thanks, I skipped the EXT_NUMERATOR and EXT_DENOMINATOR, it was driving me nuts. 

[upsss]

WITH_VEXT
EXT_NUMERATOR
EXT_DENOMINATOR

I am sorry, still cannot get it to test zeners.  The voltage across the zener is the correct voltage, PC3 is 1/10 the zener voltage and the display is blinking unknown ...  Everything else is working fine, any ideas?

[hapless]

And it doesn't show the zener voltage while you're holding down the button?

[madcat]

Here's a scan I made of the AY-AT PCB... in the image, the bottom side is flipped, which I find convenient when probing from the top side.

thanks for the pic edavid. nice and clear. 

what is still bugging my head is : why did some users who bought this AY-AT type tester complained when they received 2pcs of 3.3k and 1pc of 33k, said that it should be vice versa in numbers.
from the PCB label and PDFs given by Willem52 above, looks like AY-AT does need 2pcs of 3.3k and 1pc of 33k.

here's one of them :

Hi, I bought this ESR meter,
-what is his mark ? M328 ? GM328 ?
-somewhere it is possible to download the latest software for 16MHz crystal ?

I bought it in aliexpress from store "All sea Store" and not everything is OK...
a) unpopulated SMD components (Seller has the pictures already mounted SMD)
b) 1x missing resistor 33 k? (1x more resistor 3.3 k?)

thanks

am i missing something here? 

[Willem52]

I checked my made pictures also and I see only 2 x 3K3 and 1 x 33K resistors.

[upsss]

And it doesn't show the zener voltage while you're holding down the button?

OK, I got it.  I didn't know I had to hold the button down for so long (>5 sec.).  It is kind of awkward, first the display blinks a few times Unknown..., then it goes into the encoder Selection mode, then it restarts again and only then it display the (Vext) Zener voltage. 

You have to remember, the original test current is very low so the displayed Zener voltage would be much lower than the typical Zener rating.  I have tripled the original maximum test current and it helped a little, however the actual Zener current would still be much lower because it depend on the tested Zener voltage and its power ratings.   Overall, I don't think it is worth the effort of adding the additional Zener testing circuitry.   An adjustable bench power supply with a current limiting resistor would give you better results.  I will post some pictures of my tester once I clean it up a little.

[upsss]

Here is my final tester, not much room left in the box.  If anyone is interested here is a quick tour.  The main tester is a T3-T4 board with a an Arduino rotary encoder, 16 MHz crystal and an input protection relay all powered by a 18650 Lithium battery.

Top left side is the lithium battery charger and protection circuit.  Bottom left side is the main 5V output step up converter (3.7v to 5v) which replaces the original 5v linear regulator.  Right side is the Zener testing 28V output step up converter (3.7v to 28v identical to the 5V output converter). 

Adding the 3rd converter caused initially some ringing on the 3.7v input which was the reason the display blinked a couple of times on turn on.  Adding an LC filter fixed the problem.  For a small plastic box with 3 separate PWM converters, everything is behaving quit nicely. 

The only problem I am still experiencing is inherent to this particular tester design as its processor powered by 5v drives directly the display controller which is designed to operate on 3.3v.  If I turn the encoder quickly, the display will sometime lockup.  The easiest way to recover from that was to add a reset switch which you can see at the bottom center of the board with a pin hole in the case.

[stolz]

I am a newbie and would appreciate any help. I built an AY-AT transistor tester kit that I got on ebay (TOMTOPTECH).  This has firmware 1.12K and  8 MHz crystal. The unit does work and it completes the calibration sequence, but I am getting very inaccurate measurements and there is no repeatability when retesting the same component. Most resistors read incorrectly, however a 270 ohm and a 1.5K ohm did read correctly. Capacitors seem to always read a much lower value than expected. (This is actually my second attempt with this kit. The first one exhibited the same issues that I have described so the seller exchanged it for the one I just completed and unfortunately it also has the same problems.) I am a reasonably experienced kit builder so I don't think there is a problem with mis-located components or improper soldering. One thing that seems unusual was that during the calibration routine, the Ri-Hi value comes up as a smaller number than the Ri-Lo value, although I admit I have no idea what this means.

I had also previously built a  transistor tester from Banggood (ST7565 128x64) and that one has worked extremely well so I am using that as a reference point to judge the AY-AT which seems to be off by a mile. Can anybody suggest what the problem could be with the AY-AT and how to go about fixing it? 

If this involves changing the firmware, I did have to do that on my Banggood tester and I was successful (despite my lack of knowledge) based on the excellent instructions provided by generous contributors to this forum.  Thanks in advance for any help.

[stj]

make sure you cleaned off the flux,
and dont trust the quality of the test socket.

[mojoe]

I have an EZM MK-328 in the case. It looks like this one: http://i.ebayimg.com/images/g/ZOUAAOSwcBhWZP31/s-l500.jpg

It originally had 1.12k firmware. I just tried to flash the latest K firmware and am having trouble. I have successfully flashed firmware on two different, older testers, so I know the procedure.

Using a USBASP, I flashed the firmware HEX file. I got a verification error. Now, when I try to re-flash or erase,  I get the following:

avrdude: error: program enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
         Double check connections and try again, or use -F to override
         this check.

When I use the -F option, I get this:

avrdude: error: program enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
avrdude: AVR device initialized and ready to accept instructions
avrdude: Device signature = 0x4c0000
avrdude: Expected signature for ATmega328P is 1E 95 0F

As I said, I have flashed other testers before with no trouble. What happened this time? How can I fix it?

[mojoe]

Ok, I got it working again. Some research made me thing that it was a timing issue with the USBASP.

I'm not sure, but when I flashed the earlier component tester boards, the USBASP probably had the original Chinese firmware (which used to give a clock error). I later flashed the USBASP with the official firmware, which didn't give the clock error.

Just now, I flashed the USBASP with this firmware: https://github.com/bperrybap/usbasp/tree/1.06-alpha

I am now able to communicate with the EZM tester again. I am flashing it now. I hope I picked the correct firmware.

EDIT: I tried two different firmwares. Does anyone know which K firmware is correct?

[Smelter]

I bought a MK-328 in the middle of this year (to measure the coil of a relay) to further my project of a narrow boat monitor, that I was drawn into creating an Instructable for, as they were giving away LinkIt ONE cards. I'm now at the stage of making a working tachograph. I bought the Rigol DS1054Z (haven't we all) after Dave's rave review, and was looking for a frequency reference source to prove my work in progress design. Yesterday I switched on my MK-328 and held the switch down longer than needed and found the menu table listing a frequency generator!
24hrs later, after trawling this forum, and locating the manual for the 1.12k version of the software, I have a working test bed to make progress with without having to buy a separate signal generator.
Thanks to everyone here on the forum and the open source community for helping along this hobbyist.
Best wishes and a happy new year to all.