$20 LCR ESR Transistor checker project

[Boleslaw_J]

@ carl1961

The current used 2.8-inch 240x320 LCD TFT displays with ILI9341 or ST7789 drivers are powered by 3.3 V. To connect them to the AY-AT tester, whose microcontroller is powered by 5 volts, an additional interface must be used to reduce the voltage level.
Here is an example of such an interface.

[carl1961]

Thanks Boleslaw_J ,

I already have a 16 MHZ Crystal on the main board, that's why the crystal is missing from your  644 Adapter. Do i need to remove it and install on adapter?

Of course not. The location of the external resonator is not important.

Thanks  Boleslaw_J,  that's what I read from your post    https://www.mikrocontroller.net/topic/transistortester-avr?page=32#7426316

[Feliciano]

Dear madires:
I'm still working, with low priority, on the fonts.

IIRC, Karl-Heinz used to show the test of the bitmaps continously as it fit the screen (reminds me a typewriter). You on the other hand plot 8 chars per line. Because there is the case of small and/or narrow fonts on a high_res LCD (like 8x16 on 160128), I wonder whether it would take too much code to do something like:
if((screen_witdh/font_width>17);then plot_16_char_per_row;else plot_8_char_per_row /*as done now*/)
That way we would have to scroll less, and get a better understanding of the whole set.

What do you think?

[Boleslaw_J]

Thanks Boleslaw_J ,
I already have a 16 MHZ Crystal on the main board, that's why the crystal is missing from your  644 Adapter. Do i need to remove it and install on adapter?

Of course not. The location of the external resonator is not important.

Thanks  Boleslaw_J,  that's what I read from your post    https://www.mikrocontroller.net/topic/transistortester-avr?page=32#7426316

If you want to know exactly what I meant, check out the content of the post I wrote earlier on the subject:
https://www.mikrocontroller.net/topic/transistortester-avr?page=31#7396852

[madires]

IIRC, Karl-Heinz used to show the test of the bitmaps continously as it fit the screen (reminds me a typewriter). You on the other hand plot 8 chars per line. Because there is the case of small and/or narrow fonts on a high_res LCD (like 8x16 on 160128), I wonder whether it would take too much code to do something like:
if((screen_witdh/font_width>17);then plot_16_char_per_row;else plot_8_char_per_row /*as done now*/)
That way we would have to scroll less, and get a better understanding of the whole set.

A similar suggestion was already on my to-do list (implemented a few days ago). The alternative output prints all available characters without an index address and uses the complete display width.

[Strateg58]

Hi guys. Which one of you has implemented the LOPT/FBT function in the transistor tester.? It doesn't work for me. See if I have connected the circuit correctly.

[madires]

It seems that Vcc and Gnd are reversed. From the README:

Code: [Select]

Pinout for control output via probes:
  Probe #1:  Vcc (5 V)
  Probe #2:  pulse output (with 680 Ohms resistor to limit current)
  Probe #3:  Ground
  T0:        counter input


[Strateg58]

Thanks Madires. And to connect to +5 volts, or is it enough to connect to Pin1

[carl1961]

Finally got AY-AT Running, with von Boleslaw J. (boleslaw_43) Adapter_m328_m644_AY-AT. made a adapter from His photo FotoAlbum_TT_diagram. attached is eagle cad of the adapter and the kicad version to CNC mill, putting 4 jumpers (green traces) on back, because I can only do one sided PCB's.  I forgot to mirror the board , when doing the Milling file gcodes and had to solder the chip directly  to pcb (or redo it). Now to make small cables for screen and tweak the Case. 

[madires]

Thanks Madires. And to connect to +5 volts, or is it enough to connect to Pin1

Probe #1 is fine.

[rogerdammit]

Thanks, I remember that discussion, but the conclusion was not clear to me.

I'm trying now that toolchain, downloaded from ZakKemble's github, but it gives me compile errors. I'm troubleshooting what it is.

Code: [Select]

avr-size: invalid option -- C


I'm getting the same error. Can you please post the fix?

[Feliciano]

I rolled back to the original avr-size.

[Kim Christensen]

Thanks, I remember that discussion, but the conclusion was not clear to me.

I'm trying now that toolchain, downloaded from ZakKemble's github, but it gives me compile errors. I'm troubleshooting what it is.

Code: [Select]

avr-size: invalid option -- C


I'm getting the same error. Can you please post the fix?

I made the following changes to my makefile:

#   @avr-size -C --mcu=${MCU} $<
   @avr-objdump -Pmem-usage ${NAME}

[carl1961]

Signing off with this Project, It was fun. 
Attached firmware is using the 74HC4050AP Adapter posted on my last post.

[carl1961]

STL file for case and pictures of testing

[Feliciano]

It's my understanding that after pondering pros and cons, the Sampling ADC development has been put on hold for m-firmware. So looking at the quartz crystal measurement options for this, I have some comments about the documentation:
Section 3.1.12. Frequency Counter of CTester 1.51m doc points: "The circuit diagrams for both are depicted in Karl-Heinz’ documentation."
However, on TTester 1.13k (2021) doc I notice the basic frequency measurement circuit, but not what referred from 1.51m doc.
And back to 1.51m doc, I think 3.1.13 and 3.1.14 are both the options of 3.1.12, so IMHO those should be 3.1.12.1 and 3.1.12.2.

Anyways, I looked at the schematic of the Hiland M644, and I notice the implemented (extended) hardware option. Could that be ported to an smaller MCU?
It's not like I'm testing xtals everyday, but anyways I know the workaround: to have k-firmware handy.

[madires]

The extended frequency counter is part of the extended Transistor Tester circuit with ATmega644 shown in Karl-Heinz' documentation (Figure 2.16.). I think it should be possible to use an ATmega328 with an I2C display to free up three I/O pins to control the frequency counter frontend.

[indman]

Anyways, I looked at the schematic of the Hiland M644, and I notice the implemented (extended) hardware option. Could that be ported to an smaller MCU?
It's not like I'm testing xtals everyday, but anyways I know the workaround: to have k-firmware handy.

Pay attention to this simple modification, which was suggested earlier by Yuriy_K. I think it can be easily adapted to test quartz on both k-firmware and m-firmware. You only need 1 port for the frequency meter input.
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg4564999/#msg4564999

[Feliciano]

Thanks, I've overlooked that post.

That more simple circuit seems easier to connect by the existing f-input port of a clone?, or as you say, we would have to allocate one pin for this?
Anyways, it looks the HCF4060B it's being used as a /16 frequency divider. I suppose that would have to be taking under consideration on the firmware or measurements.

I'm not familiar with that IC, so looking at the datasheets, I notice the manufacturers recommend to add an additional resistor to what Yuriy_K implemented. That series resistor is supposed to be "for power limitation and assuring a minimum transconductance". For further study, I refer an example (of the SMD equivalent) with some recommended values.

[indman]

That more simple circuit seems easier to connect by the existing f-input port of a clone?, or as you say, we would have to allocate one pin for this?

Connect wherever is most convenient for you! The main thing is to simply understand the principle of operation of this circuit.

I'm not familiar with that IC, so looking at the datasheets, I notice the manufacturers recommend to add an additional resistor to what Yuriy_K implemented.

Why do you need this if Yuriy_K has already done a lot of work and showed you that most quartz are perfectly detected and tested by this method and this schematic?

[Feliciano]

Please don't get me wrong, I don't doubt it works without the resistor. I'm just suggesting what could be done for further improving it (perhaps enabling it to reach higher frequencies), and/or recommended as an official hardware frontend.

[indman]

Feliciano, this circuit can be assembled in a few hours if you want or maybe even faster on a breadboard. Check its work and then tell us about your experiments and improvements, I think that many people will be interested.

[madires]

If you build Yuriy_K's HCF4060B based frontend you can simply use the basic frequency counter option in the firmware and add a line to the source code to multiply the frequency by 16.

[Feliciano]

Yeah, I was thinking on breadboard this, because it's simple. My local provider has old stock of the IC, so I'll buy one to start the process. The thing is I don't have an f-input CTester handy, so I was thinking to use a 5MHz oscilloscope instead.

I'll let you know maybe next week.

[Strateg58]

It seems that Vcc and Gnd are reversed. From the README:

Code: [Select]

Pinout for control output via probes:
  Probe #1:  Vcc (5 V)
  Probe #2:  pulse output (with 680 Ohms resistor to limit current)
  Probe #3:  Ground
  T0:        counter input


I changed the connection on the recommendation of Madires. The result is the same. The scheme does not work. I changed the capacity of C2, changed the connected transformers. There are no fluctuations after C2. If no one responded, then no one is using this function.