$20 LCR ESR Transistor checker project

[indman]

flodo,thanks for video - the program works normally, I don't see any problems in work of a tester.

[madires]

flodo,сan you make small video of work of the LCR-TC1 with a new firmware U4?

I think it is better to wait for a video from someone with the transistor-mod since I am not sure if it behaves correctly.

If you press the button for at least 300ms at power-on the tester will enter the auto-hold mode (no cycling, blinking cursor at the bottom right). And after displaying the result of the last check two short button presses will trigger the menu. If this is working fine your firmware for U4 should also run without any problems with the k-firmware.

[indman]

Still it is possible to change an operating mode of the Test button in config.h
#define UI_AUTOHOLD 

[flodo]

If you press the button for at least 300ms at power-on the tester will enter the auto-hold mode (no cycling, blinking cursor at the bottom right). And after displaying the result of the last check two short button presses will trigger the menu. If this is working fine your firmware for U4 should also run without any problems with the k-firmware.

Like this?

https://www.youtube.com/watch?time_continue=1&v=tloRxvvWxuc

Btw, looks like the battery settings are wrong - right (15.x V)?

[madires]

Yep, but I've noticed some bad characters/texts in the menu. Have you updated also the EEPROM? And yes, the battery voltage is wrong. My guess is that BAT_DIRECT isn't enabled (BAT_NONE and BAT_DIVIDER need to be disabled).

[indman]

The wrong voltage of the battery and excess symbols are small malfunctions which are easily corrected.
Config.h
#define BAT_R1           0
#define BAT_R2           1
The most important that management by the Test button works without problems.

[madires]

Those settings are for older versions (IIRC, before 1.32m).

[indman]

I have opened the config.h file from your distribution kit 1.33m. In him I see these settings:
/*
 *  Voltage divider for battery monitoring
 *  - BAT_R1: top resistor in Ohms
 *  - BAT_R2: bottom resistor in Ohms
 */
#define BAT_R1           10000
#define BAT_R2           3300

 It is wrong or doesn't work any more?

[seanspotatobusiness]

My AY-AT clone doesn't turn itself off if left alone for several minutes and also doesn't turn off if I try to switch it off manually. If I use the rotary encoder to self "switch off", the screen refreshes and the tester doesn't switch off. Does this suggest a fault? I hope to replace the microcontroller with one flashed with 1.33 (m-firmware) whilst it the one it came with is running 1.12.

[madires]

I have opened the config.h file from your distribution kit 1.33m. In him I see these settings:
/*
 *  Voltage divider for battery monitoring
 *  - BAT_R1: top resistor in Ohms
 *  - BAT_R2: bottom resistor in Ohms
 */
#define BAT_R1           10000
#define BAT_R2           3300

 It is wrong or doesn't work any more?

They work, but they are meant for BAT_DIVIDER. BAT_DIRECT ignores them and the firmware will be a few bytes smaller. Therefore BAT_DIRECT is the preferred setting in case of a direct battery monitoring without any voltage divider.

[madires]

My AY-AT clone doesn't turn itself off if left alone for several minutes and also doesn't turn off if I try to switch it off manually. If I use the rotary encoder to self "switch off", the screen refreshes and the tester doesn't switch off. Does this suggest a fault? I hope to replace the microcontroller with one flashed with 1.33 (m-firmware) whilst it the one it came with is running 1.12.

Yes, there's something wrong with your tester. Please check the power control signal (ATmega328 PD6). It should change to low when powering off.

[flodo]

I attached linked to TC1 U4 firmware v0.2 - the standy mode should work now: https://github.com/atar-axis/tc1-u4/releases
The TC1 standby power consumption seems to be around 0.11mA, so my 2000mAh battery should - in theory and when disregarding self-discharging - last for around 2 years standby. That's okay but not really good... According to the datasheet the consumption of U4 is lower than 0.1uA in power-saving mode, so what is drawing so much power?

@madires: have you ever measured the consumption? what are your results?


Another question: are there any graphics somewhere like in the shipped firmware?

[seanspotatobusiness]

My AY-AT clone doesn't turn itself off if left alone for several minutes and also doesn't turn off if I try to switch it off manually. If I use the rotary encoder to self "switch off", the screen refreshes and the tester doesn't switch off. Does this suggest a fault? I hope to replace the microcontroller with one flashed with 1.33 (m-firmware) whilst it the one it came with is running 1.12.

Yes, there's something wrong with your tester. Please check the power control signal (ATmega328 PD6). It should change to low when powering off.

PD6 remains at 5 volts when I select "switch off". The LED at the top of the PCB turns off whilst the rotary encoder is held down but the voltage on PD6 stays on and when the rotary encoder is released, the screen refreshes.

[madires]

The TC1 standby power consumption seems to be around 0.11mA, so my 2000mAh battery should - in theory and when disregarding self-discharging - last for around 2 years standby. That's okay but not really good... According to the datasheet the consumption of U4 is lower than 0.1uA in power-saving mode, so what is drawing so much power?

@madires: have you ever measured the consumption? what are your results?

Not yet, but zappenduster did (15µA).

Another question: are there any graphics somewhere like in the shipped firmware?

Just the symbols for 3-pin semiconductors. Graphics which automatically scale to the screen resolution and font size would increase the firmware size considerably.

[madires]

PD6 remains at 5 volts when I select "switch off". The LED at the top of the PCB turns off whilst the rotary encoder is held down but the voltage on PD6 stays on and when the rotary encoder is released, the screen refreshes.

Remove the ATmega, press and hold the rotary encoder and measure the voltage at PD6.

[flodo]

Unfortunately my U4 (STC15L104W) is now dead after all... (yes, this time it really is  )
If someone in europe can offer me a new one, or tell me where I can buy one, i would really appreciate it.

Update:
After searching for a while: You can replace the STC15L104W by a STC15W104 or STC15W204. In fact I would recommend to do so because a fully charged Battery is around 4.2V, in this case there are still around 4.0V at U4 behind the diode. The absolute maximum rating of the STC15L104W is 3.6V, the STC15W104/204 has a maximum of 5.5.
Yes, I know - 0.4V will surely not destroy the IC... but it is a bad design anyway, there is not even a voltage regulation for U4.

[indman]

There are 2 options of a chip STC15L104 with power 2,4-3.6v and STC15F(W)104 with power 3.8-5.5v, then for option with STC15F104 the diode which I have marked red in the drawing is necessary, and for option with STC15L104 - isn't necessary and is even harmful because it overestimates supply voltage by 30% above passport!

[indman]

@indman:
The STC15Wxxx is rated for 2.4 - 5.5V (not 3.8 - 5.5V like the STC15Fxxx). So the diodes shouldn't be a problem, right? Neither D3 nor D0.

Not essentially what lower threshold of voltage(2.4v or 3.8v), it is possible to use any of the chips.The main thing that top  voltage makes 5.5v.I have shown the D0 diode on a photo

[Azure]

But, where is D0 on the PCB? I didn't knew about this one.

On the circuit I have drawn for the TC! I have that D0 in Indmans drawing drawn as D4, not sure if that helps you flodo.

[madires]

Yep, D3 is needed to power U4. And D0's purpose seems to be to bring U4's I/O pins up to nearly 5V to match the ATmega.

[flodo]

I removed my last comment because it was totally misleading.
Let's see if I got it right now:

There are at least three variants of the STC15:

• STC15Lxxx - supply voltage of 2.4 to 3.6
• STC15Fxxx - supply voltage of 3.8 to 5.5
• STC15Wxxx - supply voltage of 2.5 to 5.5

U4 is powered by the battery (via D3) as long as the 78L05 is not up yet - right? Therefore, U4 is powered by 3.5-4.0V (3.7-4.2V minus voltage drop at D3) at startup. The point is, 4.0V is too high for the STC15Lxxx and 3.5V is too low for the STC15Fxxx
U4 is then enabling the step-up (U5, SD6271) at start-up, which powers, among others, the 78L05.

Now, since the 78L05 is up, the voltage at U4 is now 4.8V (5V - 0.2V D0 drop) - which is even higher and therefore much too high for the STC15Lxxx.


The only one which does really fit both phases is the STC15Wxxx.
Removing D0 is not really a clean solution since then the I/O ports are at another level as the ATmega is.

[madires]

You got it right!

[Azure]

I have shown the D0 diode on a photo

Indman, do you have a link to that complete circuit.  I would like to compare it to the one I have drawn.  I have attached my current one.

Note: LCD sub pcb is not correct on my drawing as I just started adding in the parts for it.

I see D3 not only as a voltage drop to U4, it blocks the 5V from feeding back to the USB Lipo charger and D4 stops the V+ from the 5V supply.

I think the U4 L/F/W part numbers are worth looking into in respect to the opersting voltsges.  One concern is the F may not start up when the battery is a little low on its voltage (Edit: As flodo said in the previous post)

[indman]

https://yadi.sk/d/yW8xa5NJgUo5z
You can download the schematic diagram on many clones which I have collected in one archive at this link. You come into the "LCR-T1" folder - inside there are folder "Schematic diagram" and the TC-1.spl7 file. At me isn't present in LCR-T1 clone hands. This scheme was drawn by one of owners sleska of such device from the Russian website vrtp.ru.
It is possible to open the *.spl file the SPLan program - demo version is located here https://www.electronic-software-shop.com/lng/en/demo-versionen/

[flodo]

@indman: Could you please export the splan-schematic to pdf for me? i am running linux 
@Azure: FIY, the U5 boost-IC is a SD6271 The "697" behind "AL" is just a LOT number