$20 LCR ESR Transistor checker project

[scaramonga]

Hello all, I was recommended to come here for help, and I hope one of you brainy folks can?

I got one of these (GM328), this exact one:https://www.amazon.co.uk/gp/product/B07DJ4DSBH/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1

I put it together OK, and it works, sort of, but it keeps alerting 'weak battery 5.6v', even though batteries are brand new, and on DC 7.5-12v its same error, 'weak battery 5.6v'?  It's like its not getting correct voltage.  Screen is a little dim also, but probably due to the max 5.6v problem.

I'm having a stab in the dark and guessing its the 'regulator' (HT7551)?, but then again, I'm probably way off the mark lol!

I'm not as good as you lot, and understand only the basics, so be gentle guys

Any help much appreciated, thanking you kindly.

[indman]

scaramonga,do you have a voltmeter or multimeter to measure the voltage at the test points of the circuit?

[hamlet600]

i have a lcr-t4 and upgrade with both m and k firmware, test all setting for lcd and two lcd pin option but noting show on lcd
even increase contrast number in software .and all thing advised by other user
ps.when i restore factory backup firmware its ok

this is my exact pcb diagram

thanks

[Ser9ei]

hamlet600,
There are two versions of this t4 clone - “stripGrid” and “noStripGrid”.
Describe of this different you can find in the markus’s manual (see “7.0.3. T3/T4” section in the last version of manual).

[madires]

... or read the "Clones" file. If

Code: [Select]

#define LCD_RESET        PD4            /* port pin used for /RES */
#define LCD_A0           PD3            /* port pin used for A0 */
#define LCD_SCL          PD2            /* port pin used for SCL */
#define LCD_SI           PD1            /* port pin used for SI (LCD's data input) */
#define LCD_CS           PD5            /* port pin used for /CS1 (optional) */

doesn't work please try

Code: [Select]

#define LCD_RESET        PD0            /* port pin used for /RES */
#define LCD_A0           PD1            /* port pin used for A0 */
#define LCD_SCL          PD2            /* port pin used for SCL */
#define LCD_SI           PD3            /* port pin used for SI (LCD's data input) */
#define LCD_CS           PD5            /* port pin used for /CS1 (optional) */


[hamlet600]

this was my fist thing to change in firmware( by checking pcb trace Pd4 is not conected anywere) so it should be second pin assignment
also with/without stripgrid option,but no difference.

if something else you could advise its preciated

again big thanks for such a nice project and support

[Ser9ei]

hamlet600, please attach your firmware's configuration files here (makefile, config, config328)

[indman]

hamlet600,show a real photo of your clone from the side of the details
Is she the same as here?
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg3403834/#msg3403834

[hamlet600]

hamlet600,show a real photo of your clone from the side of the details
Is she the same as here?
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg3403834/#msg3403834

no its not same it hAS 2 SERIES DIODE instead resistor
after all tweaks it show like following display
seems to all pixels are on not just only text

[indman]

hamlet600, you have a very high contrast! Decrease the contrast value through the main menu of the tester.

[madires]

The output is shifted by four pixels. If you have LCD_OFFSET_X enabled please disable it (or vice versa). The other issue seems to be the contrast setting. Try to change the contrast via the menu and see if it helps.

[hamlet600]

by decreasing contrast to 10 and disable offset_x  and LCD_FLIP_Y everything is ok

is it normal lcd switch off/on by pressing key for move between menu items?

thanks.

[hobbyist]

Hello, what are the advantages and drawbacks of the K firmware vs. the M firmware?  Here is what I know about so far:

K firmware:  Sampling ADC method can measure small capacitors with 0.01 pF resolution.
                    16 MHz maximum clock rate.
M firmware: 20 MHz maximum clock rate.
                   
I have just ordered an AY-AT tester kit and a programming device.  I suppose that either firmware version would work fine.  Would the M firmware give me better options for the device's menus, or the way that the results are displayed?  Are there other advantages to the way that it takes measurements?  Does the faster clock speed give faster measurements? 

[indman]

hobbyist
K-Firmware also supports operation at 20MHz clock rate!
But, most of the Chinese ATMega328 at 20MHz are unstable, so the optimal frequency for both firmware versions is 16MHz. This is the experience that many owners of similar clones have gathered.

[madires]

is it normal lcd switch off/on by pressing key for move between menu items?

Yes, the T4's designer replaced the power indicator LED with the LCD's backlight LED to save a few cents.

[madires]

Hello, what are the advantages and drawbacks of the K firmware vs. the M firmware?  Here is what I know about so far:

K firmware:  Sampling ADC method can measure small capacitors with 0.01 pF resolution.
                    16 MHz maximum clock rate.
M firmware: 20 MHz maximum clock rate.
                   
I have just ordered an AY-AT tester kit and a programming device.  I suppose that either firmware version would work fine.  Would the M firmware give me better options for the device's menus, or the way that the results are displayed?  Are there other advantages to the way that it takes measurements?  Does the faster clock speed give faster measurements?

As indman already has mentioned, both firmwares support a 20 MHz MCU clock. With the hardware LC meter option (additional circuitry) the m-firmware is also able to measure down to 0.01 pF and 1 nH. It offers many additional features like IR decoder, IR sender, and servo check for example. Simply try both firmwares and choose the one you like. Or buy two clones and run one with the k-firmware and the other one with m-firmware.

[indman]

is it normal lcd switch off/on by pressing key for move between menu items?

To eliminate this problem for all clones T4, it is enough to install a 1kOhm resistor in the control circuit of the Test button! 
As a result, when you press the button, the backlight stops turning off and the value of the load current decreases.

[DAIRVINE]

Madires:
Menu:
Your menu scan method is unusual and clunky. It seems a short press for next item, a long press to select and a double press to exit. It helps to put a resistor in series with the switch, I used 470k to avoid darkening the backlight.
Disabled people (think Professor Hawking) first had electronic scanning with a single switch in 1962, and since then the universal method is to display all the menu options on one screen. Then press(nothing happens)  and release the button to start scanning, indicating each menu item in turn. When you get to the correct menu item press(it stops) and release(it selects the item) Then either an action happens or a new menu appears. You may also need to debounce the switch.
To wake up the LCR T4 press the button. Then do the auto thing. If the button is pressed again go into the menu system. The double click thing is quite hard to do perfectly and is not intuitive.
You could for example have a table of strings to generate the display menu and on selection get a scan number and use a case statement to decide what happens.
Even in 1965 people were dialing numbers with the telephone, changing volume and channel on the TV, writing letters etc.
If you do any work on the menu system, please can I suggest that you consider this option?

I have just bought a LCR T4 with same characteristics as below using LCD_ST7565R as the LCD, the ISP header has pin 1 marked by a square pad and is correct for IDC cable from below, corrected from the LCR T4 png schematic:
 

by decreasing contrast to 10 and disable offset_x  and LCD_FLIP_Y everything is ok



thanks.

[madires]

Would a rotary encoder work for you? It's supported and makes some things more simple.

[DAIRVINE]

Potential uses of a LCR T4 and similar.
For people experimenting with making their own diodes for crystal sets. Staying on a diode only test is helpful for poking around on a mineral. With a parallel capacitor you could even plot the characteristic. For home made tunnel diodes a large series inductor might be rather better for plotting the characteristics. Then there is finding new mineral combinations. Silicon Carbide LEDS anyone? Home made transistors?

For vacuum diodes (with a separate heater supply) there is also contact voltage and some triodes provide gain at low voltages.For transistors it should be possible to measure switching time and possibly Ft for some. With an extra B-E capacitor perhaps hfe vs collector current.

Couple of other things that might be tested could be capacitor absorption and capacitor non linearity, (capacitance varying with voltage, eg most ceramic types except COG). Again this would involve staying on one test and finding out more about the tested item.
I know, you only have 32k.

[DAIRVINE]

Would a rotary encoder work for you? It's supported and makes some things more simple.

Yes, rotary encoder is fine, though I have a T4.
I worked in disability so was trying to pass on some knowledge from that experience.
You may find the odd idea useful, or perhaps not, and I did not mean to offend you.
I am dead impressed with what you have achieved with something so simple.

[hamlet600]

is it normal lcd switch off/on by pressing key for move between menu items?

To eliminate this problem for all clones T4, it is enough to install a 1kOhm resistor in the control circuit of the Test button! 
As a result, when you press the button, the backlight stops turning off and the value of the load current decreases.

 AT WHICH POSITION DO YOU MEAN?

[indman]

AT WHICH POSITION DO YOU MEAN?

I showed the place with a red arrow 

[DAIRVINE]

AT WHICH POSITION DO YOU MEAN?

I showed the place with a red arrow 

I fitted my resistor as shown, but on my T4 I had to cut both the tracks leading to the switch and reconnect the tracks but without the switch using some fine enamelled wire. Then I fitted a 470k resistor from the BL to the switch to replace the cut track. I used a higher value resistor to avoid backlight dimming when switch is pressed. This resistor mod makes using the menu system practical.

[DAIRVINE]

"It is possible to make a transistor using Galena (lead sulfide, PbS). Silvery hunks of Galena are often available from rock shops and science museum stores. You can even make your own by melting sulfur and lead powder over a flame. Look up keywords such as "cat's whisker diode" and "crystal radio" to find out more.
The trick to making a transistor is to use a hyper-clean, freshly-cleaved crystal face, to sharpen your cat's-whisker contacts by dissolving the tips using electrolysis, and then to put the tips within 0.05mm of each other (or preferably within 0.01mm). Obviously the latter is the hardest part. Better use a microscope! The authors of the following article found that the base/emitter junction was critical: it HAD to act as a good rectifier. The base/collector junction wasn't as important. They got some power gain, but their beta was in the single digits. Others have mentioned that if you break open a 1N34 glass diode to expose the Germanium chip, you can make a crude transistor with a similar procedure. Old Germanium audio power transistors probably do the same, while giving much larger semiconductor area on which to play."
"Crystal Triode Action in Lead Sulphide, P. C. Banbury, H.A. Gebbie, C. A. Hogarth, pp78-86. SEMI-CONDUCTING MATERIALS, Conference proceedings, H.K. Henisch (ed), 1951 Butterworth's scientific publications LTD 1951."
From:
http://amasci.com/amateur/transis.html

Note that point contact transistors were formed with a high current pulse which improved the characteristic. They also can have negative resistance effects so the circuits can be different.