$20 LCR ESR Transistor checker project

[+Mikie]

Well, from what I understand, our "Asian partners" don't release the source code of their gadgets, which is technically illegal (breaks GPL licence), and also very annoying when they change something and don't tell us. Plus the usual "luck of the draw" quality components which may be within the original spec one day, and "close enough" the next. Which is really sad in multiple ways, it's generally understood that they would sell more products to a bunch of industrious people with screwdrivers and sodlering irons if they would release absolutely everything. Not to mention free testing and feedback to continue improving things.

It's the general consensus here that the clone marked "AY-AT" on the board is the closest to the original. Mine actually doesn't have it printed on there, but it looks right. There are other versions, some of which have added onto the original design, but alas - they aren't telling us what exactly has been changed and added software-wise, so most of us avoid those but some are determined to keep digging through the guts to figure out how it works.

[madires]

Sorry for my lasy ass (i didnt read all tread), but tel me please  whats the difference between this project vs original old german project vs china clones?

Please read https://github.com/svn2github/transistortester/blob/master/Doku/trunk/pdftex/english/ttester.pdf

[EEV2K]

Since a relay handles more current than a CMOS switch it's better to use the relay. The residual voltage you've mentioned is caused by an effect called "dielectric absorption" (https://en.wikipedia.org/wiki/Dielectric_absorption ), and for an electrolytic cap it can be 10-15% of the original voltage. Input protection was an afterthought for caps and resulted in the two simple circuit options which have some drawbacks. A proper input protection would require a complete redesign which would make the tester more complex and expensive. I'm a friend of discharging caps via a resistor before checking them with the tester.

Thanks Azure and madires.  If I understand dielectric absorption correctly, let's say that I got a 330uF/200V electrolytic capacitor and I connected to a 5VDC.  15 minutes after the initial discharge, dielectric absorption causes a "reloaded" voltage of 5VDC*0.15=75mV.  Now I discharged it again, would I get another 75mV*0.15=11mV?  But let's say that I connect the same capacitor to 200VDC until it fully charges then discharge it.  15 minutes after discharge, I should get 200VDC*0.15=30V.  Now if I connect this to Component Tester without the relays, I have a good chance of killing the 328P, right?  On some microchips other than 328P, I see a spec for ESD protection, would ESD protection protect against this?  TTester chapter 5.3.1 says step 1 of capacitor measurement is discharging of capacitor if the voltage is below 1.3V.  So if the capacitor is 30V, then it will not get discharged and the Component Tester should say "CELL".  PC2 would remain input only and it is high impedance.  So if 328P dies, it did not die from having more than 40mA of current going through PC2 pin.  It died because PC2 pin cannot handle more than a voltage of Vcc+0.5V (page 364, Table 32-1 of datasheet), right?

[madires]

Any voltage higher than Vcc plus Vf of the pin's clamping diode can cause damage based on the current flowing. A low current is handled by the clamping diode (IIRC, 1mA for ATmega) but a larger current will damage the clamping diode, the I/O pin or even more. The protection relay and the TVS array are meant to take the larger part of the current of a charged cap.

[flodo]

Just to let you know, yesterday the STC15W204S arrived, unfortunately they do NOT fit (as a replacement of U4).
The biggest problem is, that Pin 1 is not an INTerrupt (there are some other issues too... but most of them are super easy to fix by modifying the software).

The STC15W104S does fit, in fact - it is the one which STC recommends as a replacement of the STC15Lxxx series... I ordered some and will report back


Btw: v0.3.0: https://github.com/atar-axis/tc1-u4/releases

[seanspotatobusiness]

Edit: I inserted a BC237B and now it comes on when I press and release the rotary encoder but it ignores whatever components I connect and goes straight to a screen where it flashes "Vext=0mV". It then stays there without switching off and doesn't not respond to the rotary encoder. Should I try another transistor?

Maybe a problem with the rotary encoder?

The rotary encoder seems very difficult to remove even when trying with an SMD rework hot air gun. Is it possible to test it in-circuit or does it need to be removed?

[madires]

You can check the rotary encoder in circuit.

[Azure]

The rotary encoder seems very difficult to remove even when trying with an SMD rework hot air gun. Is it possible to test it in-circuit or does it need to be removed?

If you have not already tried one trick is to add some regular leaded PbSn solder (just solder on top of the current solder) to the pins before trying to remove them.  This mixes with the higher temp solder and the overall melting temp goes down and the part is easier to desolder/remove.

[EEV2K]

Any voltage higher than Vcc plus Vf of the pin's clamping diode can cause damage based on the current flowing. A low current is handled by the clamping diode (IIRC, 1mA for ATmega) but a larger current will damage the clamping diode, the I/O pin or even more. The protection relay and the TVS array are meant to take the larger part of the current of a charged cap.

TVS, is this the SRV05-4 and P6KE6V8A that is in Figure 2.2b?

A question about reusing pins:  RC4 is currently connected to a 2.5V voltage reference, and RC5 measures  battery voltage via a 1:4 voltage divider, if I also want to use PC4 and PC5 for I2C_SDA and I2C_SCL respectively, would it be possible?   And similarly for PD2 and PD3 which I am currently using it as  LCD_SCLK and LCD_D/C respectively but I would like to dual use as KEY_INC and KEY_DEC but what modification do I need to make to the circuit?

I apologize if someone else already ask these question because I am pretty sure someone else did.  To prevent this from happening in the future, how do I search just within the topic "Re: $20 LCR ESR Transistor checker project"?

[EEV2K]

I noticed that Markus' version can support up to 20MHz.  I am trying to decide whether I should unsolder 8MHz crystal and solder a 20MHz crystal in its place.  What is the benefit of having MCU clock running at 20MHz vs 8MHz?  Higher frequency generation and measurement.  I think both are currently limited at 1/4 MCU clock.  Faster PWM which is currently 1/1024 clock MCU.  But more power would be used, although probably only a small fraction of ~50mA it's currently using, am I right?  Would it measure components faster? What elese?

[madires]

TVS, is this the SRV05-4 and P6KE6V8A that is in Figure 2.2b?

Yep!

A question about reusing pins:  RC4 is currently connected to a 2.5V voltage reference, and RC5 measures  battery voltage via a 1:4 voltage divider, if I also want to use PC4 and PC5 for I2C_SDA and I2C_SCL respectively, would it be possible?   And similarly for PD2 and PD3 which I am currently using it as  LCD_SCLK and LCD_D/C respectively but I would like to dual use as KEY_INC and KEY_DEC but what modification do I need to make to the circuit?

If you disable the battery monitoring (BAT_NONE), the external voltage reference and the protection relay (both are disabled by default) you can free up PC4 and PC5 for I2C. The increase/decrease push buttons are wired the same way like the rotary encoder (see Karl-Heinz' documentation for the rotary encoder).

[madires]

I noticed that Markus' version can support up to 20MHz.  I am trying to decide whether I should unsolder 8MHz crystal and solder a 20MHz crystal in its place.  What is the benefit of having MCU clock running at 20MHz vs 8MHz?  Higher frequency generation and measurement.  I think both are currently limited at 1/4 MCU clock.  Faster PWM which is currently 1/1024 clock MCU.  But more power would be used, although probably only a small fraction of ~50mA it's currently using, am I right?  Would it measure components faster? What elese?

Karl-Heinz's k-firmware supports also 20 MHz since a few months. Other benefits are faster display output and slightly better resolution for low value caps and inductors. And yes, you won't need a car battery.

[EEV2K]

A question about reusing pins:  RC4 is currently connected to a 2.5V voltage reference, and RC5 measures  battery voltage via a 1:4 voltage divider, if I also want to use PC4 and PC5 for I2C_SDA and I2C_SCL respectively, would it be possible?   And similarly for PD2 and PD3 which I am currently using it as  LCD_SCLK and LCD_D/C respectively but I would like to dual use as KEY_INC and KEY_DEC but what modification do I need to make to the circuit?

If you disable the battery monitoring (BAT_NONE), the external voltage reference and the protection relay (both are disabled by default) you can free up PC4 and PC5 for I2C. The increase/decrease push buttons are wired the same way like the rotary encoder (see Karl-Heinz' documentation for the rotary encoder).

I can move battery monitoring and external voltage reference to ADC6 and ADC7 so I can still keep the functions.  What about AREF?  Was there any reason I couldn't just move external voltage reference to AREF?
How would I use ADC6 and ADC7 or AREF?  Do I just change in config_328.h

Code: [Select]

#define TP_REF           PC4       /* test pin with 2.5V reference and relay */
#define TP_BAT           PC5       /* test pin with 4:1 voltage divider */
to

Code: [Select]

#define TP_REF           AREF      /* test pin with 2.5V reference and relay */
#define TP_BAT           ADC6      /* test pin with 4:1 voltage divider */
I haven't make up my mind about using relay or not.  I would probably have to keep 2.5V reference voltage at PC4 if I want to use relay since ADC6, 7, and AREF are all input only.

The dual use of increase/decrease push buttons and LCD display, I don't understand how it would work.  Does LCD only need to communicate with the 328P when we try to change what is being displayed or does it communicate every times it refreshes?  I can see noises on the Nokia 5110 (PCD8544) that is why I think there is some kind of refresh rate.  Right now PD2 is connected to LCD_SCLK, but if you look at Table 2.1 and 2.7, the rotary encoders are not connected to LCD_SCLK but instead to other LCD pins.  (I think Table 2.2 which has rotary encoder 1 connected to ST7565 STRIP_GRID is behaves completely differently, right?)  Do I need to move PD2 to some other LCD pin such as LCD_DN(MOSI)?  Another reason I ask is because I have the SCE pin on the LCD tied to the GND, so the LCD is enabled all the time.  Doesn't this means that any voltage change on PD2 and PD3 is going to affect the LCD? PD2 and PD3 are currently connected to 10K resistors then to LCD pins, following Figure 2.6 I would need to connect PD2 and PD3 via 10K resistors to 5V.  This probably means I need to

Code: [Select]

5V--10K--|
PD--1K---|--<10K--LCD
         |--PUSH_BUTTON--GND
PCD8544 's LCD_Data() calls SPI's SPI_Write_Byte() (bitbang version).  And in there it sends data to LCD by calling

Code: [Select]

SPI_PORT |= (1 << SPI_MOSI);
SPI_PORT &= ~(1 << SPI_MOSI);
which sets PD to either 5V or GND.  LCD would see 5V when PD=1 and 0.4V when PD=0, so I think above circuit would work.  But what about the problems I discussed earlier:
1) does LCD needs SPI communication all the time?
2) does the pushing the button affect subsequent SPI communication?
3) does the firmware need to query the button and communicate via SPI at the same time?  I think long push is only for the Test button not increase/decrease button.
4) do I need to move PD2 from LCD_SCLK to say LCD_DN(MOSI) keep in mind that SCE of PCD8544 is always connected to GND?

[madires]

You can't re-purpose AREF because it's part of the ADC. You either add a buffer cap for the internal voltage references (Vcc and 1.1V) or feed an external reference voltage which will render the internal ones useless. And the tester is designed to use the internal voltage references for the ADC.

Sharing I/O pins between display and rotary encoder usually requires the display's /CS to prevent the display to interpret input from the rotary encoder as data. By selecting the shared lines carefully it can work with a fixed /CS tied to ground. When the firmware reads the rotary encoder it changes the I/O pins from output mode (for the display) to input mode, and back again afterwards. The SPI bus is only active when data is sent to the display.

[EEV2K]

Sharing I/O pins between display and rotary encoder usually requires the display's /CS to prevent the display to interpret input from the rotary encoder as data. By selecting the shared lines carefully it can work with a fixed /CS tied to ground. When the firmware reads the rotary encoder it changes the I/O pins from output mode (for the display) to input mode, and back again afterwards. The SPI bus is only active when data is sent to the display.

On first attempt, I can't get inc and dec buttons to share the same I/O pins as the LCD_D/C and DN(MOSI) without interfering with the display.  I'll try it again next week.  If I can't get it to work, I was thinking about using PC3 and PC5 as inc and dec key.  I might end up using a single cell li-ion as battery and if that is the case, then I don't need Battery voltage.  Zener can go on ADC6 or ADC7.  No I2C anymore, can't fit it in.  I can't find anything similar to SRV05-4.  Is P6KE6V8A needed because..?  Don't know, I originally thought maybe it has a lower clamp voltage, but it seems the clamp voltage is still higher than 5V.  Why is P6KE6V8A and the 100nF capacitor needed?  Wouldn't the thyrector in SRV05 work just as well?  I can't find any relay with 3 throws or poles (forgot which) but I did find a relay with 2 ??.  So maybe I use it on TP1 and TP3 and leave TP2 without protection.

[EEV2K]

A question about using AVRDude to program both flash memory and eeprom:

This is the command I am using.  AVRdude is from ArduinoIDE.

Code: [Select]

avrdude -CC:\Users\Demo\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf -v -patmega328p -cstk500v1 -PCOM4 -b115200 -Uflash:w:ComponentTester.hex:i -U eeprom:w:ComponentTester.eep:i

Program is always successful but kind of slow.  Increasing baud rate from 19200 to 115200 doesn't seem to improve the speed very much.  The eeprom writing part is extremely slow even though it's only 760 bytes.   Is my syntax incorrect?  Here is the output of avrdude.  As you can see below, programming 760 bytes of eeprom takes 36.24 seconds.

Code: [Select]

avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
         Copyright (c) 2000-2005 Brian Dean, [url]http://www.bdmicro.com/[/url]
         Copyright (c) 2007-2014 Joerg Wunsch

         System wide configuration file is "C:\Users\Demo\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino9/etc/avrdude.conf"

         Using Port                    : COM4
         Using Programmer              : stk500v1
         Overriding Baud Rate          : 115200
         AVR Part                      : ATmega328P
         Chip Erase delay              : 9000 us
         PAGEL                         : PD7
         BS2                           : PC2
         RESET disposition             : dedicated
         RETRY pulse                   : SCK
         serial program mode           : yes
         parallel program mode         : yes
         Timeout                       : 200
         StabDelay                     : 100
         CmdexeDelay                   : 25
         SyncLoops                     : 32
         ByteDelay                     : 0
         PollIndex                     : 3
         PollValue                     : 0x53
         Memory Detail                 :

                                  Block Poll               Page                       Polled
           Memory Type Mode Delay Size  Indx Paged  Size   Size #Pages MinW  MaxW   ReadBack
           ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
           eeprom        65    20     4    0 no       1024    4      0  3600  3600 0xff 0xff
           flash         65     6   128    0 yes     32768  128    256  4500  4500 0xff 0xff
           lfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           hfuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           efuse          0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           lock           0     0     0    0 no          1    0      0  4500  4500 0x00 0x00
           calibration    0     0     0    0 no          1    0      0     0     0 0x00 0x00
           signature      0     0     0    0 no          3    0      0     0     0 0x00 0x00

         Programmer Type : STK500
         Description     : Atmel STK500 Version 1.x firmware
         Hardware Version: 2
         Firmware Version: 1.18
         Topcard         : Unknown
         Vtarget         : 0.0 V
         Varef           : 0.0 V
         Oscillator      : Off
         SCK period      : 0.1 us

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.03s

avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: reading input file "ComponentTester.hex"
avrdude: writing flash (27730 bytes):

Writing | ################################################## | 100% 18.20s

avrdude: 27730 bytes of flash written
avrdude: verifying flash memory against ComponentTester.hex:
avrdude: load data flash data from input file ComponentTester.hex:
avrdude: input file ComponentTester.hex contains 27730 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 9.34s

avrdude: verifying ...
avrdude: 27730 bytes of flash verified
avrdude: reading input file "ComponentTester.eep"
avrdude: writing eeprom (760 bytes):

Writing | ################################################## | 100% 36.24s

avrdude: 760 bytes of eeprom written
avrdude: verifying eeprom memory against ComponentTester.eep:
avrdude: load data eeprom data from input file ComponentTester.eep:
avrdude: input file ComponentTester.eep contains 760 bytes
avrdude: reading on-chip eeprom data:

Reading | ################################################## | 100% 2.07s

avrdude: verifying ...
avrdude: 760 bytes of eeprom verified

avrdude: safemode: hfuse reads as D9
avrdude: safemode: efuse reads as FD
avrdude: safemode: Fuses OK (E:FD, H:D9, L:F7)

avrdude done.  Thank you.


[+Mikie]

I'm no command line fan, so I use "AVRDUDESS", a GUI addon for AVRDUDE. And I program my processor on a separate board using AVRISP clone and SPI. I guess it takes longer to display the status then to program.

I've noticed that fuses are not set unless you set them separately. I thought Makefile would calculate them and do that, but no. Bug or a feature?

[madires]

Is P6KE6V8A needed because..?  Don't know, I originally thought maybe it has a lower clamp voltage, but it seems the clamp voltage is still higher than 5V.  Why is P6KE6V8A and the 100nF capacitor needed?  Wouldn't the thyrector in SRV05 work just as well?  I can't find any relay with 3 throws or poles (forgot which) but I did find a relay with 2 ??.  So maybe I use it on TP1 and TP3 and leave TP2 without protection.

P6KE6V8A and the 100nF cap aren't required but help. The P6KE6V8A is able to handle a harder hit than the SRV05. And the relay needs just two throws (see Karl-Heinz' documentation).

[madires]

I've noticed that fuses are not set unless you set them separately. I thought Makefile would calculate them and do that, but no. Bug or a feature?

In most cases the fuses have to be set just once (brand new ATmega). I don't see any benefit in setting the fuses to the same values again and again when programming a new firmware.

[+Mikie]

I've noticed that fuses are not set unless you set them separately. I thought Makefile would calculate them and do that, but no. Bug or a feature?

In most cases the fuses have to be set just once (brand new ATmega). I don't see any benefit in setting the fuses to the same values again and again when programming a new firmware.

I often say and write things without proper explanation. But it all sounded good in my head, I swear!

What I meant to say is: adjusting the values in appropriate files, then compiling, then uploading does NOT set the fuses to required values posted elsewhere in this thread (even with the checkbox "set fuses" checked). I had to set them manually after programming. Thinking about it now, it could be Avrdudess problem?

[indman]

Btw: v0.3.0: https://github.com/atar-axis/tc1-u4/releases

flodo,One of owners of LCR-TC1 has updated STC15L104W firmware your version 0.3.1. The tester works, but there is one problem. I will cite his words:
"After check of components not always correctly fulfills switching off. I have inserted, let us assume, the capacitor, I have checked it. The screen has gone out. I insert other component, I press the button, the screen with the message "Good bye" lights up at once and the tester "hangs". Doesn't react to the button. To have to open a tester and to switch-off the battery, otherwise it will be discharged in zero. Can after measurement on this message hang. And, the more on the battery, the glitch is more often than a charge."

[madires]

What I meant to say is: adjusting the values in appropriate files, then compiling, then uploading does NOT set the fuses to required values posted elsewhere in this thread (even with the checkbox "set fuses" checked). I had to set them manually after programming. Thinking about it now, it could be Avrdudess problem?

Don't know, I don't use Avrdudess. If you are using make and avrdude it would be a simple "make fuses".

[seanspotatobusiness]

I removed my rotary encoder and determined that it may be defective by connecting the CLCK and DATA signals to 5 V via LEDs and suitable resistors. Only one of the signals produced a flashing LED when rotating the encoder. Is it true that water getting into an encoder can damage it? I did take care when cleaning flux from my board but I suppose it's possible that some water (70% isopropanol, 30% water) was able to ingress. What is the appropriate encoder to replace with? Does it matter how many steps it has per rotation? Thanks!

[EEV2K]

I'm no command line fan, so I use "AVRDUDESS", a GUI addon for AVRDUDE.

I tried it.  The program looks pretty good.  The speed is the same though.  At least this means my avrdude syntax is correct.  I wonder if there is a need to reprogram the EEPROM every time.

[dazz1]

Hi
I know the answer I want will be somewhere in the 208 pages of this thread but I will ask anyway.

Where can I get "the best" version.  I would prefer assembled but a kit would be OK.
I just need a link.

Do the assembled versions need modification to replace zeners and high tolerance resistors etc?

Dazz