$20 LCR ESR Transistor checker project

[texaspyro]

They are slightly and slowly improving the quality of their services, but they still have a long way to go.

So, someone (customs?  post office?) is only stealing a third of the packages now?  I stopped sending stuff to Italy several years ago when over half the stuff I sent to Italy never arrived in the customer's hands.   I would ship if the customer assumed full liability for the delivery...  the customers seemed to be rather familiar with the problem  And these were relatively small and inexpensive items.   I never had any problems receiving stuff from Italy so I assume the problems tended to originate in customs.

[j-man]

Last year my brother sent me a laptop keyboard from London. After three months the package wasn't arrived yet...  He went back to the UK post office and reported the issue: I don't know if it's just a coincidence, but a few days later a "Poste Italiane" car stopped by my gate, somebody threw a cardboard through the bars and rushed away (by chance I was looking at the window...). Of course the cardboard was half-opened, there was some masking tape on the edge... but at least my keyboard was there. Guess I've been lucky.

[jakeisprobably]

Can someone thoroughly check my work please? Is there anything I need to change before uploading the KiCad file on the official replica? (the second one is taken directly from the tarball)

[upsss]

You are missing a junction dot at AVCC, C3 and Vcc

[v81]

I ordered the TFT unit on eBay a week or 3 ago and it recently arrived, have built it and had a struggle with the layout, which lead to this thread.
It's working now, but must say i'm blown away by the info here.

Based on the bits & pieces i've read so far it appears other firmware is available, would love to get hands on it.
Could someone link me the best place to get the latest firmware for these?

Am also interested in building a new unit with better componentry and tighter tolerances, even using 1206 or 0805 SMD and an ATMEGA328P QFP.
Has anyone considered this? would make a great SMD project.

Lastly, an issue, i'm finding the menu is incredibly sluggish, and 'misses' some detents when turning the encoder.
Is this normal?
Would swapping to a 16 or 20 MHz Xtal solve or at least improve the performance?

Thanks in advance for any answers!
- pic of my particular unit....

[madires]

Can someone thoroughly check my work please? Is there anything I need to change before uploading the KiCad file on the official replica? (the second one is taken directly from the tarball)

I suggest to move C10 to the LDO because it's the LDOs output cap. The MCU has its local 100nF bypass cap.

[madires]

Based on the bits & pieces i've read so far it appears other firmware is available, would love to get hands on it.
Could someone link me the best place to get the latest firmware for these?

k-firmware: https://github.com/svn2github/transistortester/tree/master/Software/trunk
m-firmware: https://github.com/svn2github/transistortester/tree/master/Software/Markus (read the README!)
documentation: https://github.com/svn2github/transistortester/blob/master/Doku/trunk/pdftex/english/ttester.pdf

Am also interested in building a new unit with better componentry and tighter tolerances, even using 1206 or 0805 SMD and an ATMEGA328P QFP.
Has anyone considered this? would make a great SMD project.

Of course  There are several SMD versions of the tester already. 

Lastly, an issue, i'm finding the menu is incredibly sluggish, and 'misses' some detents when turning the encoder.
Is this normal?

Crappy rotary encoder? A knob could possibly help.

Would swapping to a 16 or 20 MHz Xtal solve or at least improve the performance?

A higher clock rate improves some time related measurements and helps with colour displays. You'll have to build the firmware for the specific clock rate and program the MCU. The 20 MHz clock rate is only supported by the m-firmware.

[texaspyro]

Am also interested in building a new unit with better componentry and tighter tolerances, even using 1206 or 0805 SMD and an ATMEGA328P QFP.

Use a socketed DIP processor chip.  That way WHEN (not IF) you blow up the chip it is very easy to replace.  You really don't want to do SMD rework on the processor every time the gremlins attack.  Also, I keep a couple of chips with different firmware configurations handy and can swap them out in a few seconds.

[jakeisprobably]

I'm trying to do a detailed breakdown of ALL ATmega328 Transistor Tester Options from the minimum system to the full bells and whistles version. Does the following list look correct so far?
Absolute Minimum System
1.) 3× 680R resistors matched within 0.1% 
2.) 3× 470k resistors matched within 0.1% 
3.) 2× 100nF Capacitors (AVCC & AREF to GND)
4.) 1× 10k Resistor (Reset Pin)
5.) ATmega8/88/168/328
6.) Your Choice of LCD + Supporting HW
7.) 0.1% scientific laboratory grade power supply w/5.000 volt output
8.) Push Button
NOTES:
Internal 8MHz Oscillator
Internal Atmega IC Vref

M A I N  O P T I O N S
Interface
Option 1 minimum/required
Push Button
Option 2
2× Push Buttons (Increase/Decrease)
Option 3
Rotary Encoder w/integrated push button
Option 4
Touch Screen (M-firmware Only as of 9/2017)

External DC Supplied Vcc Power
Option 1
0.1% scientific laboratory grade precision power supply w/ 5.000 volt output
Option 2
5 Volt Regulator w/ better than 0.4% precision
Option 3
5 Volt Regulator + 0.1% Precision Voltage Reference IC

Battery Based Vcc Power
Option 1
On/Off Switch + Test Button(s)
Option 2
MCU Controlled Timed Shutoff w/ Supporting Hardware + Push Button
Battery Option A
9 Volt Battery + LDO 5 Volt Regulator w/ better than 0.4% precision
Battery Option B
9 Volt Battery + LDO 5 Volt Regulator + 0.1% Precision Voltage Reference
Battery Option C
3.7v Lithium Battery + Boost Converter + LDO 5 Volt Regulator + 0.1% Precision Voltage Reference

Oscillator
Option 1
Internal 8MHz
Option 2
External 8MHz Xtal
Option 3
External 16MHz Xtal
Option 4 (M-Firmware Only)
External 20MHz Xtal
Option 2-4A
Standard oscillator Capacitors (~20pF)
Option 2-4B
1× Standard oscillator Capacitor + 1× Trimmer Capacitor ~0-30pF (Requires Frequency Measurement Device w/ Precision Disciplined Reference Oscillator such as a Rubidium Osc or GPSDO)

LCD Variations
~HD44780 (16×2/Hitachi Character)
~ST7036 (Dog-M)
~PCF8812 (Nokia 3410)
~PCF8814 (Nokia 1100)
~PCD8544 (Nokia 3310/5110)
~SSD1306 (microscopic size-OLED)
~NT7108 (Graphic Mono)
~ST7565 (Graphic Mono)
~LCD2004 (20×4 Character)
~ST7735 (Graphic Color 🐌)
~ILI9341 (Graphic Color 🐌)
~ILI9342 (Graphic Color 🐌)
~ST7920 (Giant Graphic Mono)

Additional Auxiliary Features Options
 ~TVS Array/Relay Circuit Protection
 ~Frequency Output
 ~Voltage Measurement (0.1-50 Volts)
 ~Zener Threshold Testing
 ~Infrared Remote Frequency ID
 ~Xtal Measurement (K-firmware)
 ~Optocouple IC Tester
 ~PWM LCD Backlight (LM339 based)
 ~UART Serial Communication
 ~Solenoid Tester
 ~Direct External Frequency Measurement
 ~High/Low Freq. Measure w/Buffer&Prescaler
 ~Self Calibration Capacitor Circuit
 ~Sampling ADC Relay+Capacitor (K-FW Only)

Unofficial/None Supported Auxiliary Features
  ~Bluetooth Serial Communication
  ~LC Meter Circuit (LM311)
  ~LC Meter Circuit (ATtiny3213)
  ~Xtal Test Circuit (PIC16F628A)

The idea is to subdivide every extra circuit option on a schematic... you will see
 With this level of breakdown I should  be able  to explain everything from the 328 version visually without language. Basically I'm creating an ikea instructions type version of the pdf.

Note: This list has been edited to account for all posts of mistakes and omissions after this one as of September 15 2017.

[bitseeker]

Wow, Jake, that's a lot of info once it's all put in a nice list like that. Overall, it seems OK. One correction: the rotary encoder has an integrated push button (i.e., rotate to change value, press to select).

[jakeisprobably]

Russian Thread part 2... finally. I got 4 corrupt images that gave me troubles, then uploaded a complete video just to find out someone pulled some copywrite shenanigans on a song from 1937....I deleted the whole thing and redid it instead of letting that joker force me to monetize an OS project reference like this.
  The first Version 2 testers are on part 2 Including a really nice ATmega644 DIP version created by Nick, Ocela, and GMS. This  section of the Russian forum thread included a lot of testing and comparisons. I tried to separate these images into a second half of the video and sped them up otherwise the video would be too long.
https://youtu.be/UKjD-Y0iqHY

The playlist of all 7 I've made so far
-Jake

[madires]

M A I N  O P T I O N S
Interface
Option 1
Push Button
Option 2
Rotary Encoder

Actually the test push button isn't an option, it's always required. But we go more options:
- two push buttons (increase/decrease)
- touch screen (m-firmware only)

Additional Auxiliary Features Options

 ~TVS Array/Relay Circuit Protection
 ~External Frequency Measurement
 ~Frequency Output
 ~Voltage Measurement (0.1-50 Volts)
 ~Zener Threshold Testing
 ~Infrared Remote Frequency ID
 ~Xtal Measurement
 ~Optocouple IC Tester
 ~PWM LCD Backlight (LM339 based)
 ~UART Serial Communication
 ~Solenoid Tester

And some more:
- self-adjustment cap
- relay with cap for Sampling ADC

For frequency measurements there are two options. One simple one directly connected to T0, and an extended one with LF/HF crystal oscillators, input buffer and prescaler.

[jakeisprobably]

Actually the test push button isn't an option, it's always required.

I don't want this to read like I am trying to contradict or anything  like that. I'm certainly no expert at these things by any stretch. I am simply exploring my own curiosity and using this device as a broader learning platform where I have the wonderful resource of smarter people than myself that I can ask for help on a few details while I try to give back by sharing my notes as I go.
  That said, why did Markus Frejek write "(optional)" next to the test button on one of his first schematics of the project? (image attached)
  That was my reasoning point for this statement.

[madires]

For the first schematic the push button is optional because that tester is switched on by a separate switch. The second schematic requires the push button for switching on the tester. And the current design of the power control is based on the second schematic. You could still use a power switch if you modify the power circuit, but you wouldn't be able to use the menu and other functions controlled by the push button.

[MLXXXp]

Absolute Minimum System

I believe you're missing a 10K potentiometer for the LCD display contrast control.

[jakeisprobably]

@MLXXXp
Your certainly correct. I have been debating how to address displays. I don't want a beginner that's even greener behind the ears than me, to think that there is anything special about a 16×2 LCD. I just haven't 100% figured out how I can convey that message visually yet. I went ahead and neutralized the LCD under min sys though. Thanks for the heads up.

   I'm working on overlapping schematics where I can explore/demonstrate the different parts of the circuit in a video. This should allow me to show every detail of the circuit in depth bit by bit.... Still trying to figure out how I want to do the displays though

Revised Main Schematic J1.0 attached along with my 1st draft of a minimum system on the same layout (parts are based on Tom666's 1.7 design and Schematic sans voltage regulator)

Edit: I already see I need to take the junction off of the DC input connector.

[jakeisprobably]

Did anyone else notice this little bit of Russian magic? I could be totally oblivious, and this may have already been discussed here, although I don't remember seeing it.
  Ocela used the Zener threshold circuit to rig up a way to test linear regulators around pages 138-139 of the main VRTP.ru TT thread. Indman summarized it on his summary thread here (Russian)
 I tried to clean up the English G-Translate of Indman:
The principle of checking the output voltage of linear regulators L78 XX is shown in the image (L78xx.jpg) below. The jumper is used to select the mode of the voltmeter:
1. Test Zener diodes (jumper)
2. Test L78 XX (no jumper)
To test low voltage linear regulators (e.g. L78L33 ) you need to be aware of their high input voltage breakdown. It is necessary to lower the Vext (external voltage from boost converter, aka zener threshold test circuit) to limit the threshold voltage. This problem is solved by connecting a zener in parallel (output = 7-10V..)

[jakeisprobably]

I will try to finish matching up a revised PCB diagram for the AY-AT with parts delineators tomorrow and I still need to double check it against this schematic. Is there anything I should improve to make this layout more conventional, or easier to understand?

[N9XYP]

I have finally got around to testing my upgraded tester. 1.11k GM328 no rotary, no ISP to 1.29m with rotary, ISP.

A few of things -
Tested some known good 2n3055 (various vintage) and house numbered RCA 2n3055 (3700161). The 1.29 shows lower gain, higher leakage, and a few tested as either a cap or two resistors. One tested as a JFET. Two had B-E resistors (7k & 8k), no gain listed and C-E diodes.

Tested a batch of germanium 2n404. The gain and leakage were not near the 1.11 reading. No pattern in the difference. Also 3 of the 14 tested as Pch JFET with 1uA of Idss. Retesting them, two read as PNP BJT with near the same readings as 1.11 about half the time, JFET the other half, and the one still as a JFET.

An MCR92-3 (To-92 plastic) on 1.11 tested as a NPNp, hFE=667,Vf=.727  on 1.29 as BJT PNP+, hFE=20, Vbe=.801

Three Fairchild (I think) dual NPN (2455100 C 205) had gains of about 100 on 1.11 and 80 on 1.29. Pain to test with very short pins.

Why the large discrepancy? I can see small differences but 1/2 the gain and higher leakage when the only difference is the atmel chip?

[madires]

I have finally got around to testing my upgraded tester. 1.11k GM328 no rotary, no ISP to 1.29m with rotary, ISP.

A few of things -
Tested some known good 2n3055 (various vintage) and house numbered RCA 2n3055 (3700161). The 1.29 shows lower gain, higher leakage, and a few tested as either a cap or two resistors. One tested as a JFET. Two had B-E resistors (7k & 8k), no gain listed and C-E diodes.

Have you run the self-adjustment incl. measuring a film cap a few times? Are you powering your tester with a SMPSU? Contact problems? The BJT detection is fairly reliable for Si types, even without the self-adjustment. Are you sure that the two transistors with B-E resistor and freewheeling diode are 2N3055? Typically those types are high voltage switching BJTs for CRTs.

Tested a batch of germanium 2n404. The gain and leakage were not near the 1.11 reading. No pattern in the difference. Also 3 of the 14 tested as Pch JFET with 1uA of Idss. Retesting them, two read as PNP BJT with near the same readings as 1.11 about half the time, JFET the other half, and the one still as a JFET.

Self-adjustment? I have no 2N404 for testing but all my Germanium BJTs (mostly AC1xx) test fine.

An MCR92-3 (To-92 plastic) on 1.11 tested as a NPNp, hFE=667,Vf=.727  on 1.29 as BJT PNP+, hFE=20, Vbe=.801

That would be a BJT with a freewheeling diode on the same substrate as the BJT. Usually the one with the higher base-emitter capacitance is the correct type. Otherwise it's a 50/50 chance. The hFE can differ hugely based on which type is assumed. Have you seen table 5.3 in Karl-Heinz' documentation? Please note the results for BUL38D.

Three Fairchild (I think) dual NPN (2455100 C 205) had gains of about 100 on 1.11 and 80 on 1.29. Pain to test with very short pins.

Why the large discrepancy? I can see small differences but 1/2 the gain and higher leakage when the only difference is the atmel chip?

Again, self-adjustment? Have you compiled the k-firmware with both hFE measurement methods enabled or just the standard one? Have you tried a current k-firmware?

If you find problematic transistors please send me some samples. I'll happily investigate to improve the detection. But I don't got a crystal ball

[edavid]

An MCR92-3 (To-92 plastic) on 1.11 tested as a NPNp, hFE=667,Vf=.727  on 1.29 as BJT PNP+, hFE=20, Vbe=.801

That would be a BJT with a freewheeling diode on the same substrate as the BJT.

It's an SCR.

[madires]

I've found only a datasheet for a MCR 100. The gate trigger current is just 200µA. Is the MCR 92 similar?

[N9XYP]

I ran the self adjustment. I used polyester caps. I am using a 9V battery (new Duracell). The 1.11 is the original chip for my tester, so I have not tried other K firmwares, not sure about the settings in the chinese version.

The 3055 that showed the diodes were marked 2N3055, no HV marking. Bought a bucket of them (literally a bucket, 3 gallon size) in the 90s for $5.

I am going to reflash the chip, want to add a couple of more options. And retest these and some other parts I dug out- UJT, PUT, some odd ball diodes.

Thanks madires.

[N9XYP]

Except for the few problem transistors the 1.29m firmware is working for me.

I finally got 1.11m to compile and work. The rotary is a few seconds behind and backwards. The problem germaniums gave the same readings as the original chip.

Compiled 1.13k and the rotary will not work, and sometimes the switch as well. Get the same readings as 1.11m, 1.11m-Chinese on the problem parts.

These flags are commented-
#CFLAGS += -DNO_COMMON_COLLECTOR_HFE
#CFLAGS += -DNO_COMMON_EMITTER_HFE

[Giox040]

Would swapping to a 16 or 20 MHz Xtal solve or at least improve the performance?

A higher clock rate improves some time related measurements and helps with colour displays. You'll have to build the firmware for the specific clock rate and program the MCU. The 20 MHz clock rate is only supported by the m-firmware.

Hi !

I also just built the same model and found the slowness of the display and I thought I would pass a quartz by 16MHz, but yesterday I was reading the manual:
TransistorTester with AVR microcontroller
and a little more
Version 1.13k
Karl-Heinz K ubbeler

and on page 55 I found this sentence:

OP MHZ tells your software at which Clock Frequency in MHz your Tester will operate. The
software is tested only for 1MHz, 8MHz and additionally 16MHz. The 8MHz operation is
recommended for better resolution of capacity and inductance measurement.
Example: OP MHZ = 8

If that is true, I think a slower display but a better resolution is preferable.