$20 LCR ESR Transistor checker project

[jemp]

Tnx, Marcus for input
Found problem..  due to soldering new chip ATMEGA328P, i made short circuit, between pin 10-11  so turn-on and turn-off were connected..
My mistake;.
Firm 1.13K works TOP !! tnx Guys and Designers..

JP

[indman]

New modification English k-firmware for clones LCR-TC1(LCR-TC2,T7) based on the current 899th revision 1.13K.Quartz 8,16 or 20MHz.Font 8x15.With 8MHz quartz there will be no option to test different resonators.

The firmware will work only on clones with installed ATMega644 MCU and ST7735 display!

The author's code has been supplemented and corrected in many places to speed up the work and best display the test results:
1. Improved font 8x15, added new symbols of inductance,zener diode,triac,thyristor, "eta" as well as large symbols UJT and PUT.
2. Test results (value data) are highlighted in a separate color.
3. A full pinout for 3 contact parts is always placed at the bottom of the display for convenience when sorting.
4. A new color icon has been added to assess the battery status.
5. Measure the zener diodes at the terminals of the voltmeter "A" - "K". The zener diode symbol will appear on the display if it is connected correctly, and on the 2nd line its breakdown voltage is Vz. If the zener diode is connected as a diode, only the forward voltage drop on it will be displayed on the display Vext.
6. Improved auto-detection of UJT and fixed the display of the transmission coefficient "eta".
7. The tester's algorithm has been changed for cyclic modes [RL] and [C] - now exit from these modes without turning off the tester. Long press of the Test button - exit the cyclic mode and restart the test.
8. Fixed calculation of the capacitance of diodes at a reverse voltage of 5V (negative capacitance values are no longer displayed for germanium diodes).
9. Added calculation and display of base-emitter capacitance (Cbe) for BJT.
10. Added auto-detection of silicon and Schottky/Germanium diodes with the display of the corresponding designations in the 1st line.
11. For a more accurate assessment of the quality of the potentiometers(trimmer), a display of its total resistance between contacts 1-3 has been added, as well as the percentage of resistances R1<=>R2.
12. There are now 8 full active lines in the menu without an unnecessary "Mode-Select" line. The page mode of the menu display is enabled, which increases the speed and convenience when moving through the items.The "Switch off" item is highlighted in a separate color.

I will answer questions about receiving this modified firmware in my personal message!

[madires]

And another one:

v1.48m
- Added remote command V_F_clamp for V_f of clamping diode for Schottky transistors.
- Pin assignment for the 3 test pins/probes can be changed now (suggested by dreieck@mikrocontroller.net).
- Optional confirmation beep for valid frame/packet in IR receiver/decoder (SW_IR_RX_BEEP) or after probing is done (UI_PROBING_DONE_BEEP).
- Updated license to EUPL v. 1.2.
- Option to center-align infos and some other texts (UI_CENTER_ALIGN).
- Option to show self-discharge voltage loss of a capacitor > 50nF (SW_C_VLOSS, suggested by indman@EEVblog). Also added as remote command.
- Option to show additional info for a possible potentiometer/trimpot (SW_R_TRIMMER)
- Workaround option for clones with SCT15L104W management MCU, in case the tester turns off suddenly after the first probing cycle (PASSIVE_POWER_CTRL, based on idea from lhlad@EEVblog).
- Added option to switch boost converter for Zener check by a dedicated I/O pin (ZENER_SWITCHED, suggested by Per Hansson@EEVblog).
- New option to display values in a different color (UI_COLORED_VALUES, suggested by indman@EEVblog).
- Added precompiler check for detecting if multiple displays are configured (suggested by Per Hansson@EEVblog).
- Moved supporting configuration management from config.h and config_<MCU>.h to a new header file (config_support.h). Also added a few additional configuration checks. Fixed issue with missing text for SW_DHTXX (reported by BroMarduk@EEVblog).
- Moved UJT symbol bitmap to standard symbols.

Please download at:
- https://github.com/madires/Transistortester-Warehouse/tree/master/Firmware/m-firmware
- https://github.com/kubi48/TransistorTester-source/tree/master/Markus

[Adrian_Arg.]

very silly question, has anyone made a video of the complete process to make the hex and epp files, using the files downloaded from here
very silly question, has anyone made a video of the complete process to make the hex and epp files, using the files downloaded from here

[madires]

For example:

[dazz]

Quick question, please. I have an LCR-T4 I bought years ago. Will I get the extra functionality present in other versions of the tester if I flash this firmware, please?
https://github.com/Mikrocontroller-net/transistortester/tree/master/Software/trunk/mega328_T4_v2_st7565
I mean stuff like leakage currents for transistors, and all the extra goodies the GM328 has. Or those things are device specific?

[indman]

I have updated the comparison table of the most popular clones, taking into account the release of the new 1.48m
https://yadi.sk/d/yW8xa5NJgUo5z 
I have also updated the Russian-language pdf format instruction for 1.48m as well as the change log file CHANGES.ru

[dazz]

OK, I managed to brick my T4. I flashed the firmware using:

avrdude -p m328p -P usb -c usbasp -U flash:w:mega328_T4_v2_st7565.hex

Now I have a black screen at all times. Any ideas, please? Do I need to also flash the eep file or something?
Thanks

EDIT: Here's the avrdude command output:

Code: [Select]

avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.04s

avrdude: Device signature = 0x1e950f (probably m328p)
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: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: reading input file "mega328_T4_v2_st7565.hex"
avrdude: input file mega328_T4_v2_st7565.hex auto detected as Intel Hex
avrdude: writing flash (29334 bytes):

Writing | ################################################## | 100% 18.99s

avrdude: 29334 bytes of flash written
avrdude: verifying flash memory against mega328_T4_v2_st7565.hex:
avrdude: load data flash data from input file mega328_T4_v2_st7565.hex:
avrdude: input file mega328_T4_v2_st7565.hex auto detected as Intel Hex
avrdude: input file mega328_T4_v2_st7565.hex contains 29334 bytes
avrdude: reading on-chip flash data:

Reading | ################################################## | 100% 16.90s

avrdude: verifying ...
avrdude: 29334 bytes of flash verified

avrdude: safemode: Fuses OK (E:FD, H:D9, L:F7)

avrdude done.  Thank you.
EDIT2: Oh, I erased the entire flash memory and now I need to burn the bootloader again, right?

[dazz]

Oh! I needed to flash the eeprom file as well, of course! In case someone finds this and it helps, this is the command that worked for me:

avrdude -p m328p -P usb -c usbasp -U flash:w:mega328_T4_v2_st7565.hex -U eeprom:w:mega328_T4_v2_st7565.eep

[madires]

Quick question, please. I have an LCR-T4 I bought years ago. Will I get the extra functionality present in other versions of the tester if I flash this firmware, please?
https://github.com/Mikrocontroller-net/transistortester/tree/master/Software/trunk/mega328_T4_v2_st7565
I mean stuff like leakage currents for transistors, and all the extra goodies the GM328 has. Or those things are device specific?

Yes! Please see https://github.com/kubi48/TransistorTester-source/tree/master/trunk for the latest version. No, only hardware specific options. However, the flash size might limit the features available.

[dazz]

Quick question, please. I have an LCR-T4 I bought years ago. Will I get the extra functionality present in other versions of the tester if I flash this firmware, please?
https://github.com/Mikrocontroller-net/transistortester/tree/master/Software/trunk/mega328_T4_v2_st7565
I mean stuff like leakage currents for transistors, and all the extra goodies the GM328 has. Or those things are device specific?

Yes! Please see https://github.com/kubi48/TransistorTester-source/tree/master/trunk for the latest version. No, only hardware specific options. However, the flash size might limit the features available.

Thanks, madires. I'll try those as well... In a while, after I replace the LCD screen, cause I managed to rip the connector off. Oh well 

[elecdonia]

That is approximately what it measure in circuit.  I can pull it an measure it accurately tonight.
Does anyone know what IC U7 is?  It is not the SDB628 mentioned above; the pin wiring does not match.

U7 is very similar to SY7208CABC in the location of the contacts, but this cannot be said with 100% certainty, because the HYDSI or HYDWE marking does not appear anywhere yet.

P.S Here is an even more likely interpretation of U7 - this is AN_SY7200A (marking HY6VE). If you believe the documentation for this chip, then the output current is calculated by the formula I=0.2/R1. If R1 = 40 ohms, then the test current I=0.2/40=0.005A, that is, 5mA.

Now it remains to solve the riddle from Chinese friends -why does this circuit not withstand a given R1 current and allows it to conduct a much higher current?

I recently purchased one of these so-called "improved" LCR-TC1 transistor tester units. U1 (MCU) is mislabeled as a Mega328. The display shows "FNIRSI" when performing the self-calibration. This tester contains the U7 circuit (as discussed in this thread) to generate 30V DC for testing zeners.

For me the zener test feature worked properly a couple of times without excessive zener current, but then it failed in the mode where the zener test current isn't limited.
After it failed I measured up to 500mA into a short circuit placed on the K and A terminals. I did this test very briefly. Fortunately conducting this short-circuit current test one time did not cause any additional failures. The U7 circuit continues to generate 30V (but without any current limiting). All other functions of the tester still work OK.

I believe the failure occurred when I connected an 11V zener across the K and A test terminals while the tester was already powered up.

Here is what I suspect causes U7 to fail:

1) When powered up with an open circuit on the K and A terminals, U7 continuously generates the full 30V DC output. The filter capacitor on the 30V rail, although small, still holds a substantial amount of energy when charged up to 30V.
2) Connecting a component across K and A can immediately dump the entire 30V directly into the current sensing pin of U7, causing this pin to permanently short circuit.
3) According to the U7 datasheet the current sensing pin is only capable of handling 4V

To prevent the failure of U7 I intend to experiment with placing a resistor of perhaps 4K7 or 10K between the high end of the 40 ohm sensing resistor and the current sensing terminal of U7. Hopefully this will prevent failures of U7. The worst case test will be to have the tester powered up and then apply a short circuit between K and A.

U7 is intended for use as a current-limited LED driver. In this application the string of LEDs is permanently connected. Therefore the current limit will activate gradually as the output voltage rises soon after power up. In this case the feedback loop is always closed, preventing excessive voltage from reaching the current sensing pin of U7.

But in the transistor tester application, the output voltage rises to the full 30V when K and A are open circuit. The output voltage rises to 30V because the current-limiting feedback loop is open. Then, when a short-circuit or low resistance is applied across K and A, the entire 30V is instantly dumped into the current sensing pin of U7. This is what damages U7.

I will post my results after testing. First I must obtain a supply of replacement U7 chips. I will try to get several types that have the same pinout, including the SY7200A.

-EB

[Per Hansson]

And another one:

v1.48m
- Added option to switch boost converter for Zener check by a dedicated I/O pin (ZENER_SWITCHED, suggested by Per Hansson@EEVblog).

Here is a little picture to go together with this new option for the Hiland Elec M644 based on Indman's schematic, maybe someone can find it helpful

[elecdonia]

OK, I managed to brick my T4. I flashed the firmware using:

EDIT2: Oh, I erased the entire flash memory and now I need to burn the bootloader again, right?

A bootloader is not needed when programming the AVR MCU with the ISP header.
(On the other hand a bootloader is required to program Arduino boards via a serial or USB port. It’s easy to get confused about this.)

Upgrading transistor tester firmware always requires programming the flash and the eeprom.

Generally the fuse bytes require no changes (except possibly when changing the frequency of the crystal from 8MHz to 16 or 20MHz - could the experts please comment on this?)

Programming of the fuse bytes is required when a virgin (never used before) AVR MCU is programmed for the very first time. The factory default is 1MHz internal clock. Therefore the fuse bytes must be changed to “external crystal oscillator” or else the transistor tester will operate at only 1/8 of its normal speed.

-Elecdonia

[vklimk]

To prevent the failure of U7 I intend to experiment with placing a resistor of perhaps 4K7 or 10K between the high end of the 40 ohm sensing resistor and the current sensing terminal of U7. Hopefully this will prevent failures of U7. The worst case test will be to have the tester powered up and then apply a short circuit between K and A.

It will cause quite a big additional power consumption by device (additional 40mA or something like that) (my misunderstanding, I didn't catch the place of that resistor you proposed).
You can put protective diode or zener diode in parallel to that 40 ohms resistor. Diode will not allow over voltage on U7 sensor pin, it will cut voltage to 0,7v.

But we have to think about a case user shorted A and K terminals - in this case U7 will produce voltage near (Ubat - Vschottky) = 4v and it will be applied directly to our diode. The diode may be burned if we do not limit current. We can put 100 ohms resistor between output capacitor of U7 and K-terminal - it will limit current through diode (Ishorted = (4v-0,7v)/100ohms = 33ma). Voltage drop on this resistor in normal situation (measuring zener diode) will be equal to (100 ohms * 5mA) = 0,5v - it is very low and it should not affect zener detection functionality of TT.

[MrAl]

This is a reply to the very first post...


Hello there,

If you get a scope and frequency generator you can test for all those things and get the error down to a very low value.  This is especially useful for cap ESR which is an important specification.

Also, these little meters will never be able to read inductors except for the very small ones maybe, and maybe only air core inductors.  That's because inductors with metal cores require some excitation current to be able to get a good idea what the inductance is, and the inductance changes with DC bias so you need a way to change that also.  Sometimes the only way to measure inductors like this is to measure their characteristics while they are actually in the circuit they are going to be used in, such as a buck converter.
These harder to measure inductors include 50/60Hz line frequency inductors and switching regulator inductors as they usually have some type of specialized metal core which makes them very DC bias sensitive as well as frequency sensitive.  You can usually measure ESR with an Ohm meter for these types though.

To measure cap ESR, you can put some resistance in series with the cap and use a square wave to energize the circuit.  Looking across the cap with the scope will show a waveshape that can be analyzed that will reveal the capacitance and the ESR.  The ESR shows up as a very vertical part of the wave and measuring the current thought the resistor on channel 2 of the scope and cap voltage on channel 1 will show you the ESR by simply dividing the voltage delta by the current delta for that vertical part.  A bad cap ESR shows up very vividly this way.

[indman]

MrAl,why did you provide us with a full copy of the message February 23, 2013 from the 1st page of the topic? You could just make a short link to this post in the topic.

[madires]

Generally the fuse bytes require no changes (except possibly when changing the frequency of the crystal from 8MHz to 16 or 20MHz - could the experts please comment on this?)

If you just change the frequency the fuse bytes don't need any changes..

[madires]

Also, these little meters will never be able to read inductors except for the very small ones maybe, and maybe only air core inductors. 

The Transistortester isn't an LCR meter, but in can measure L, C and R to some extend. Get one, compare the results with a proper LCR meter, and you'll see that the Transistortester isn't that bad.

[rsjsouza]

Hello there,

If you get a scope and frequency generator you can test for all those things and get the error down to a very low value.  This is especially useful for cap ESR which is an important specification.
(...)

I agree with your remarks about the potential pitfalls when measuring inductors and capacitors, but the keyword is convenience: for a quick check these testers are exceptionally useful. 

[elecdonia]

Also, these little meters will never be able to read inductors except for the very small ones maybe, and maybe only air core inductors. 

The Transistortester isn't an LCR meter, but it can measure L, C and R to some extent. Get one, compare the results with a proper LCR meter, and you'll see that the Transistortester isn't that bad.

For years I’ve used the LC100-A to measure inductors & capacitors. The LC100-A excels at measuring small capacitors & inductors - uH & pF. That said, the LC100-A is also capable of measuring large values: 100,000uF, 50H. I recommend that everyone who enjoys using their transistor tester should consider adding the LC100-A to their test gear collection.

The LC100-A is a modern digital version of the legendary “ grid dip meter ” used by ham radio enthusiasts for nearly 100 years. It measures the unknown L or C by connecting it in parallel with an internal calibrated C or L. This forms a tuned LC circuit. An IC comparator with positive feedback drives the LC circuit into steady oscillation. Typical oscillation frequency is 1-500kHz. The internal MCU-based frequency counter measures the oscillation frequency and uses clever math to calculate and display the uH or pF of the unknown L or C.

Many Asian electronics vendors sell the LC100-A. Although quality/accuracy varies by vendor, the low cost ( < $25 USD ) allows exploring this device on a budget. The original LC100-A manufacturer is a company named MingHe. I have a genuine branded MingHe LC100-A which is quite accurate, often well within 2% when compared to high-end LCR meters. Try to find a vendor who shows a photo of the LC100-A with a MingHe label on the PC board. This is the one to buy.

Comprehensive discussions of the LC100-A may be found here:
https://www.antiqueradios.com/forums/viewtopic.php?f=8&t=365161
https://www.eevblog.com/forum/testgear/lc100-a-a-precise-lc-meter-for-3-75$/msg4596301/#msg4596301

-Elecdonia

[elecdonia]

Generally the fuse bytes require no changes (except possibly when changing the frequency of the crystal from 8MHz to 16 or 20MHz - could the experts please comment on this?)

If you just change the frequency the fuse bytes don't need any changes..

Thanks!
I’ll soon be updating the firmware in one of my transistor testers. I also intend to experiment with changing the crystal from 8MHz to 16MHz.

-E

[indman]

For several years I’ve been using a device known as the LC100-A to measure inductors and capacitors.

This information is certainly interesting to many on the forum, as well as information about measuring ESR using a generator and an oscilloscope. But I want to ask without offense - what does this information have to do with the project being discussed here? There are relevant topics for discussing these devices on the forum.

[elecdonia]

For several years I’ve been using a device known as the LC100-A to measure inductors and capacitors.

This information is certainly interesting to many on the forum, as well as information about measuring ESR using a generator and an oscilloscope. But I want to ask without offense - what does this information have to do with the project being discussed here? There are relevant topics for discussing these devices on the forum.

I agree: in this topic we should focus on the transistor tester.

My LC100-A post was intended mainly to call attention to a low-cost alternative device for measuring C and L. I was responding to several questions posted here about measuring L & C with the transistor tester.

I use my transistor testers several times per day. But I go to my LC100-A when L or C must be measured precisely, especially with RF circuitry.

To me the transistor tester represents an inexpensive device which every electronics enthusiast should have on their workbench. I am very appreciative of the efforts of the folks here on this topic who continue refining & maintaining the transistor tester project.

-E

[Yuriy_K]

Also, these little meters will never be able to read inductors except for the very small ones maybe, and maybe only air core inductors. 

The Transistortester isn't an LCR meter, but in can measure L, C and R to some extend. Get one, compare the results with a proper LCR meter, and you'll see that the Transistortester isn't that bad.

For several years I’ve been using a device known as the LC100-A to measure inductors and capacitors.

Both authors inattentively read messages with examples of measurements. I gave measurements of small capacitances < 1 pF.
When it comes to measurements of small and large inductances, it is necessary to take into account the different measurement methods and frequencies at which measurements are made.
The top row shows the readings of the TTester when the turns of inductance are compressed and the readings of the measurement of large inductance. Below are the readings of this inductance on different RLC meters at different measurement frequencies.