$20 LCR ESR Transistor checker project

[pepe10000]

Hello madires.

Once the two lines have been added to the FONT_10X16_HF font, the texts on the screen can now be read correctly.

I have recompiled with the options I need and the tester is working fine.

But after the first more thorough tests, I have discovered that some strange artifacts still come out, see attached photos.

I think the problem is in the lines:

  0x00,0x00,0x06,0x00,0x18,0x00,0x30,0x00,0x20,0x00,0x40,0x00,0x40,0x00,0x40,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,   /* 0x1a * */

Which should be like this:

  0x00,0x00,0x10,0x00,0x10,0x00,0xD6,0x00,0x6C,0x00,0x28,0x00,0x38,0x00,0x28,0x00,
  0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,   /* 0x1a * */

All the best.

[Yuriy_K]

Probably been asked before, probably by me
What does it mean when testing a cap esr when it reads 0.00ohms?surely that can't be right.

Your readings may be the result of an incorrect Adjustment. Photo 1 shows a jumper for closing the measuring contacts, an auxiliary capacitance for tuning, and the measured polymer capacitor itself. Before Adjustment, we measure the auxiliary capacity 5-10 times photo 2-3. Then, without turning off the TTester, select Adjustment in the Menu and, upon completion of the test, save the settings in Save. When checking capacitors, the polarity of the connection must be observed, this is shown in photo 4-5 (arrows show "-").
This is especially noticeable on polymer and tantalum capacitors.
P.S. Version 1.46m works great, but I'm testing with my trusted fonts.

[madires]

But after the first more thorough tests, I have discovered that some strange artifacts still come out, see attached photos.

Yep, '*' (the next character after ')') is also effected. It got the top part of the ')'. I've updated the post with the changes to include also the fix for the '*'.

[fabriciofx]

So guys,

sorry for this question, but what is the nowadays cheap chinese $20 LCR ESR test do buy? I saw some options, but I'm bit lost because some people said the best ar those we can update firmware, but I don't know.

I appreciate some suggestions!

Best Regards!

[indman]

madires,is it possible to add the option "SW_SYMBOLS_TEST" by analogy with the option "SW_FONT_TEST"?

[madires]

sorry for this question, but what is the nowadays cheap chinese $20 LCR ESR test do buy? I saw some options, but I'm bit lost because some people said the best ar those we can update firmware, but I don't know.

We had this question a few pages back. There you'll find your answers!

[madires]

madires,is it possible to add the option "SW_SYMBOLS_TEST" by analogy with the option "SW_FONT_TEST"?

Yes, it's possible.

[fabriciofx]

Hi madires!

Thanks for answer my question!

I've bought this one: https://www.aliexpress.com/item/32310123631.html?spm=a2g0o.order_list.0.0.21ef1802zWTjNT

Was it a good choice?

Best Regards!

[madires]

The MK-328 is an average clone with a nice enclosure. Nothing wrong with that. If you like to improve your tester please see Karl-Heinz' excellent documentation (https://github.com/kubi48/TransistorTester-documentation/blob/main/pdftex/english/ttester.pdf).

[cdev]

My AVR Transistor tester still sits on my desk despite my having bought test equipment that does what it did better. Why? It is really good at clarifying my thinking sometimes.. Thats the best way to put it.  Components sometimes look a certain way to it, and I find that insight invariably valuable. In saving time.
It does surprisingly well at measuring capacitance and inductance..
Its the best deal around, up there with the $6 logic probe.. thsts super useful also with sigrok/pulseview..

[Feliciano]

The characters are shifted by one. Let's check the font... Found it. Please edit font_10x16_hf.h and insert after the bitmap for '('

Hi madires,
I downloaded today your 1.46m, made, updated my T7, and got the same "Dpnqpofou..." bug.
Are you sure you updated your github file?
Regards,

[madires]

I didn't update the 1.46m archive but you can use the attached file.

[Feliciano]

I already had updated the font bitmaps according to your directions on the previous page. Thanks anyways.

[lhlad]

Hello

I have put a config of the m firmware here https://gitlab.com/a11059/t7_328_m.git that works on my recenlty purchased T7 with atmega 328 image below.
There's also a schematic in there, it may have some errors/ommisions.

Thankyou Markus.

[madires]

That new variant of the T7 seems to have a pin header for the hardware serial interface. The additional 8-pin MCU could be a level shifter for 3.3V serial? The drawback is that PB2 is used for the LCD, i.e. no signal output (PWM/squarewave/...) possible. You've changed the SPI clock to a lower rate. Was there an SPI clock issue with the LCD?

[indman]

Madires,the version of the T7 clone(photo) that Felipe Lacerda offered us on page 303 of this thread is even more mysterious?!
It is not based on the classical ATMega328 but most likely on the Chinese analog LGT8F328P. This was reported by another owner of the same clone on a Russian-language forum.

I made several different symbols set options (24x24_vfp, 30x32_hf and 32x32_hf) for m-firmware and would like to hear your opinion - are there any bugs or reasonable suggestions for corrections to the style?
In the screenshot on the left, a set of symbols with a thin outline, and on the right side a set of symbols with a bold outline. If there are no comments or amendments, then madires will add these sets to their new release of m-firmware.

[lhlad]

Yes couldn't really work out what the 15L104W is there for.  It isn't connected to anything other than the serial ports on the 328.  The only thing i've seen it do, with the original firmware, still on the original 328 but not readable, is receive some serial input from the 328 and then respond, happens every time its powered up.  The 328 send whats looks like some binary data that finishes with the ascii text "ending." the 15l104 replys with an ascii number and "OK" in ascii from memory something like "3624OK!". It didn't come with the header pins BTW I soldered them on. 

Re the spi I kept getting a blank white screen trying the hardware spi when bitbang displayed stuff.   I saw a suggestion I think you gave someone else in here to try reducing clock rate so I did quarter worked and half worked.  Possible if I go back to default it would work now because I solved another issue with my confusion over the CS and Reset pins after.  But working fine as is.
 
Oh I also changed the 5v reg, supply not really high enough for the original,  for a better LDO one and adjusted the UREF_VCC to reflect the actual when measured, not sure if should do that?  Seems reasonably accurate compared to other measure kit have access to.

Also nearly forgot to mention the IR receiver function didn't work at all with the orignal firmware, no sensible response from supplier.  I could see sensor OK with scope.  Part of the motivation for the firmware change, it works fine now.

Cheers
 

[theHWcave]

Hi Markus, I just upgraded from 1.45m to 1.46m and after applying the font fix, everything works great. Many thanks.

I use my tester (similar to MEGA_328_Colour) a lot to do in-circuit capacitance and ESR measurements and it is brilliant for that. Can you explain if the ESR menu item is different in measurement methodology from the C-monitor (which also shows ESR) ?

My reason in asking is that a lot of times I am using probes to measure on a PCB which often needs precision placement. Using 2 hands for the probes means the ESR menu is not great because it requires a button press. The C-monitor is better for me because it automatically repeats. But my problem with that method is that I need to look up to see the display which is not always possible because I may shift the probes in doing so and if that happens the readout is of course gone.

Since neither are ideal for tricky measurement conditions, I wonder what your thoughts are of a special version of the autohold similar to say Fluke and some other high-end gear.  For example, if one probes a new cap, it measures and shows the measurements on the display, but when then taking the probes off (i.e. a near zero value is detected) it freezes the display of the last previously measured good value until the probes are reapplied for another measurement. That way one can measure without having to press any buttons or needing to squint or hurry to read the display before it disappears. It would be great if that type of autohold could be enabled or disabled through the menu

Sequence could be something like this:
Event: probes in the air (=near zero measurement) --> State: Hold  (display the last value significantly greater than near zero)
Event: probes applied (=measurements significantly higher than zero) --> State: Wait  (do measuring and update values on the display)

not sure if this is too primitive to work. It is also a question of what threshold is a near-zero measurement. I know there are more fanciful algorithms where a value has to be sufficiently different (say 10%) from the previous value to get through to the display. Maybe that would work better, but then, especially in probing caps, its quite common to have a lot of close values which might not be detected as sufficiently different...

 

[indman]

But my problem with that method is that I need to look up to see the display which is not always possible because I may shift the probes in doing so and if that happens the readout is of course gone.

I do not see anything wrong with the fact that the readings will disappear for a while, which indicates that you currently have a bad connection. The C-Monitor mode was conceived and implemented precisely for this purpose, in order to monitor the change in capacitance and ESR in real time, since these parameters are unstable and can vary significantly from the influence of many factors - temperature, humidity, leakage,poor contact, etc. . It's my opinion.

It would be great if that type of autohold could be enabled or disabled through the menu

In this case, you risk getting erroneous capacity status values ​​for the reasons that I mentioned above.

[madires]

Yes couldn't really work out what the 15L104W is there for.  It isn't connected to anything other than the serial ports on the 328.  The only thing i've seen it do, with the original firmware, still on the original 328 but not readable, is receive some serial input from the 328 and then respond, happens every time its powered up.  The 328 send whats looks like some binary data that finishes with the ascii text "ending." the 15l104 replys with an ascii number and "OK" in ascii from memory something like "3624OK!".

Interesting! Then the 15L104W could be removed when running one of the OSHW firmwares. In other TC-1/T7 variants it's used to control power and the test button.

[madires]

I use my tester (similar to MEGA_328_Colour) a lot to do in-circuit capacitance and ESR measurements and it is brilliant for that. Can you explain if the ESR menu item is different in measurement methodology from the C-monitor (which also shows ESR) ?

The measurement methodology is the same, just the user interaction is different.

Since neither are ideal for tricky measurement conditions, I wonder what your thoughts are of a special version of the autohold similar to say Fluke and some other high-end gear.  For example, if one probes a new cap, it measures and shows the measurements on the display, but when then taking the probes off (i.e. a near zero value is detected) it freezes the display of the last previously measured good value until the probes are reapplied for another measurement. That way one can measure without having to press any buttons or needing to squint or hurry to read the display before it disappears. It would be great if that type of autohold could be enabled or disabled through the menu

I could add an option to display the last valid measurement result in the third text line. Would this help?

[Feliciano]

a lot of times I am using probes to measure on a PCB which often needs precision placement. Using 2 hands for the probes means the ESR menu is not great because it requires a button press. The C-monitor is better for me because it automatically repeats.

For the m-firmware, you can also set the ctester to "continous mode" instead of "autohold", and/or set the timers to allow you read the measurement results before a starting a new test cycle.

[theHWcave]

@madires

Yes, a "previous (stable) value" could work. I wonder if there might be an issue (software wise) to recognise the last previous value. I mean removing the probes produces more measurements, just the values are usually very small and normally no ESR is shown. So maybe the lack of ESR could be used?

[theHWcave]

a lot of times I am using probes to measure on a PCB which often needs precision placement. Using 2 hands for the probes means the ESR menu is not great because it requires a button press. The C-monitor is better for me because it automatically repeats.

For the m-firmware, you can also set the ctester to "continous mode" instead of "autohold", and/or set the timers to allow you read the measurement results before a starting a new test cycle.

Thanks but I am well aware of this. The problem is that neither mode works well (for me) when using flying probes to measure ESR in circuit. I don't have a hand free to press the button (autohold) and in continuous mode, if I have to concentrate on where I probe, I can't look at the display. More often than not when trying to look at the display I lose firm probe contact ever so slightly, thus removing or changing (ESR) the displayed value just before I can read it (very frustrating...). Sometimes the soldering points and traces of old kit (most likely to have developed bad caps) are a bit tarnished and hard to probe reliably despite using needle probes & pressure.
Maybe its just me but I long to have a true Fluke-style smart autohold ...

[theHWcave]

I've stumbled over LOPT/FBT testers (also called ring tester). It should be possible to design a simple hardware option for the Transistortester to do the same, i.e a test adapter for the three probes with a counter output for T0. Would you be interested in such a ring tester option?

Another question (sorry). Is there a schematic for what the tester expects as front-end for the Ring Tester (probes) option? I looked at Bob's Basic Ring Tester and its a whole standalone tester by itself. Obviously the counting and pulse gen is done by the ATMEGA but what else from Bob's circuit is needed?