$20 LCR ESR Transistor checker project

[stj]

have you tried compiling the trendy software from madires?

[upsss]

Do you have a link for this trendy software?

[stj]

https://www.mikrocontroller.net/svnbrowser/transistortester/Software/

top folder is the trendy,
bottom folder is the K version your using.

before that, check your resistors on the encoder board with a meter.
i have a feeling they could be the cause.

[spiderb]

I have several of these gadjets and my advice would be to try running it off a battery or a linear power supply. They do not like switch mode powers supplies at all
bill

[Martini]

Hello, considering getting one of these ESR kits to build. Had a look on bangGood, and there are a few to choose from.
Can someone recommend the darling? Is bangGood best bet, or aliexpress/ebay offer better ones or prices?


M328 LCD 12864 Transistor Tester DIY Kit Diode Triode Capacitance LCR ESR Meter $22.85au
http://www.banggood.com/M328-LCD-12864-Transistor-Tester-DIY-Kit-Diode-Triode-Capacitance-LCR-ESR-Meter-p-1041588.html

DIY M12864 Graphics Version Transistor Tester Kit LCR ESR PWM $25.67 (cant see difference)
http://www.banggood.com/DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-p-986954.html

DIY M12864 Graphics Version Transistor Tester Kit LCR ESR PWM With Case $31.58
http://www.banggood.com/DIY-M12864-Graphics-Version-Transistor-Tester-Kit-LCR-ESR-PWM-With-Case-p-997023.html
is the case worth $9 more. Seem to recall allignmnt issues.

GM328A Transistor Tester Graphic Wave Signal LCRRLCPWMESR Meter Inductance $20.44
http://www.banggood.com/GM328A-Transistor-Tester-Graphic-Wave-Signal-LCRRLCPWMESR-Meter-Inductance-p-997582.html

DIY Multifunction Transistor Tester Kit For LCR ESR Transistor PWM Signal Generator M328 $15.53
http://www.banggood.com/DIY-Meter-Tester-Kit-For-Capacitance-ESR-Inductance-Resistor-NPN-PNP-p-929603.html

Glad I'm not the only one bewildered by all the variants. Question is which one is the best.

I would add this one with the bigger screen and the push button for $9.35 assembled.
I actually saw this on aliexpress before finding this thread here.

I'd prefer a kit rather than an assembled unit but I also prefer to spend $9 rather than 15 (I know it's close to nothing in both cases but $9 is closer to nothing  ).
Is that one hackable into using a rotary encoder?
Will it display Vloss?


Or do you have another option (a complete kit available for a cheap-ish price) to propose?

[stj]

T4 is barebones design with no input protection.

the GM328A is much better - input protection is fitted and it has a set of flyleads for off-board testing.

[upsss]

I have several of these gadjets and my advice would be to try running it off a battery or a linear power supply. They do not like switch mode powers supplies at all
bill

I am very familiar with switch mode regulators.  The output of my step-up 5v regulator has less than 50mv p.p switching noise and I even bypassed the 5v right on the encoder. 

To eliminate anything else, I reverted back to the battery power and the 7805 regulator and I still have the same problem, turning the encoder back and forth, not even fast locks the processor.  Other than this problem, my tester including the encoder work fine.

I would like to hear from other people that have or added the rotary encoder and don't exhibit this problem.

[stj]

if your resistors are wrong, you could overload the pd1/3 pins when they are outputs.
that could drag the voltage down in the mcu and glitch it.

[spiderb]

I have the banggood diy and the clone with two switches on and I have found they do not like switch mode psus.  both have encoders fitted, both work fine on battery but play up on psus. What i have found is that it is better to run them on battery when programming them as both have fallen over after being programmed on psus even though they verified without error YMMV

bill

[stj]

I have the banggood diy and the clone with two switches on and I have found they do not like switch mode psus.  both have encoders fitted, both work fine on battery but play up on psus. What i have found is that it is better to run them on battery when programming them as both have fallen over after being programmed on psus even though they verified without error YMMV

bill

i power them through the programmer cable.

[GBowes]

Two things...

• I have added encoders to two of these devices, but neither are the same as yours... Both running some version of the 112k release and the encoder can be spun as fast as I can do it without problem.
  Generally the response is to start testing again, however, it also shows the menu from at least one location.
  The code just executes a return when the encoder count exceeds the FAST_ROTATION value (default = 10).
  
  You either have a hardware problem or possibly somehow your code is corrupt. Did you load both the flash and the EEPROM when you flashed it?
  I would suggest rather than trying to fix it by making changes to the code that you contact the author who is both extremely helpful and knowledgeable. Probably best would be to post on the microkontroller forum where he is quite active. https://www.mikrocontroller.net/topic/248078#new This is a horribly long thread and partly in German, but full of extremely valuable information on these devices and firmware. Using Chrome, Google can translate it and make it quite useful but it takes a few minutes for the translation to be finished.
  Alternatively, you can contact the author directly via email. See the front page of the documentation for his email address.
  
• The measurement accuracy of these devices is extremely dependent on an accurate and consistent VCC. A 50mV ripple is pretty good but is a +/-1% variation before any other effects on VCC. The VCC is measured at startup and I believe that is the value used for all subsequent tests. Changes in VCC during a test period will introduce errors in results with particular effect on the measurement of capacitance.
  A lot of people are using LiIon batteries so this is not your problem, although I wonder if there might not be some advantage in setting the SMPS to a slightly higher value and then using a precision LDO regulator or a regular grade LDO plus a precision reference.
  I would think that the only way your power supply could be causing your problem is if VCC is dropping below the brownout level set with your fuses. You might want to try setting the extended fuse to FD instead of FC. This would lower the BOD to 2.7V. If this solves your problem then you need to do something to stabilize the VCC.
  

Hope this helps. They are great little devices and incredibly functional and accurate considering their cost. The author has done a magnificent job of squeezing the most out of a little 8 bit processor.

Graham

I am very familiar with switch mode regulators.  The output of my step-up 5v regulator has less than 50mv p.p switching noise and I even bypassed the 5v right on the encoder. 


I would like to hear from other people that have or added the rotary encoder and don't exhibit this problem.

[GBowes]

If the pins are loaded down on output then the display would be affected.

Incorrect resistors could increase or decrease current flow when the pins are reading the encoder and may be causing a drop in VCC but since the encoder works OK at slow speeds, I think a wiring issue on the encoder PCB is not so likely.
On the other hand, I would certainly try a different encoder (only - no PCB) and test it before going about the changes to code that you are suggesting/trying.
The Fast_Rotation is almost necessary as it is the only way to escape from the automatic continuous test mode of capacitors and resistors on TP1-TP3 and from the Voltage measuring mode.

Graham

if your resistors are wrong, you could overload the pd1/3 pins when they are outputs.
that could drag the voltage down in the mcu and glitch it.

[upsss]

@GBowes, thanks for your response.  Well, I am making some progress but still don't have a good solution.  The key to the problem is, I found out by accident that problem is NOT that the processor or the software are locking up but the display controller is latching up, disabling the display and at the same time the software jumps to the menu selection.  Once you are in the menu selection, the only way to exit it is to select the "Switch off" but since the display is blank, I was stuck.  If you keep clicking the switch, eventually you will hit the "Switch off" position and that is how I found out that the processor and the software was actually still running.

Looking at my display, I found out that the display controller is designed for 3.3v and they simply drop the Vcc with two series diodes.  Now I am not surprise that I am having this problem.  I believe everyone else that is using this tester, this display controller and this encoder will experience this problem.   And yes, I disabled the internal pull-ups on the processor (CFLAGS += -DPULLUP_DISABLE).

I was convinced that if I power the encoder from 3.3v that it will solve the problem but the improvement was minimal.  I also tried a second encoder I had (the same manufacturer) and I got basically the same results.  It looks like there is another manufacturer for these encoders, I might give it a try.  Maybe someone else has a better idea.

[GBowes]

I doubt another encoder will be different. They are just make or break switches.

I was going to mention your diodes in an earlier thread as I considered them far more important than your concern about the NPN versus MOSFET but didn't want to get embroiled in a battle over definitions.
Those diodes on paper would drop 5.0V to about 3.4 - 3.6 which would probably be OK for the display. I have one of those units (the only one to which I did not add any hardware extensions) and the voltage to the display is closer to 4.1V so I expect the display to die an early death. The diodes drop very little voltage at the current levels of the LCD. Disabling the pullups helps mitigate the potential damage to the signal lines but still is far from ideal solution and I believe that you also need to add a pullup resistor to PD0. On another unit I had (which came with a 3.3V regulator on the LCD board), I added an HC4050 to translate the 5.0/3.3 v signal levels.

To your current problem... I cannot think of a good solution. I know that the author does not recommend this model due to the difficulty accessing some of the connections of the display interface. He has tested one of these and may have some suggestions that might help you get the encoder working properly.

Graham

Looking at my display, I found out that the controller is designed for 3.3v and they simply drop the Vcc with two series diodes.  Now I am not surprise that I am having this problem.  I believe everyone else that is using this tester, this display controller and this encoder will experience this problem.   And yes, I disabled the internal pull-ups on the processor (CFLAGS += -DPULLUP_DISABLE).

I was convinced that if I power the encoder from 3.3v that it will solve the problem but the improvement was minimal.  I also tried a second encoder I had (the same manufacturer) and I got basically the same results.  It looks like there is another manufacturer for these encoders, I might give it a try.  Maybe someone else has a better idea.

[upsss]

The only reason I am considering trying a different encoder manufacture is that I was really surprised that powering the encoder with 3.3v didn't solve the problem.  I would really like to hear from anyone that has this particular tester with the rotary encoder working without any problems. 

As far as powering the LCD, I might add another diode in series with the 2 existing.  Better yet I think I still have some of these 3 junction diodes in a DO41 package I used many years ago which I believe are obsolete now. 

[stj]

i still think the problem is related to the resistors, maybe not what they have printed on them.
they should limit the current to a point that wont effect the display.

they should be on vcc btw, not 3.3v - they are interacting wih the 5v device.
you dont want them bleeding low current 5v back to your 3.3v source.

as for the display, i would replace the diodes with a 3.3v LDO powered from the 5v rail.
something like a 1117

the display inputs are supposed to be 5v tolerant on the datasheet i had someplace.

btw, thanks for bringing my attention to the fast-rotation menu entry/exit function - i didnt know about that.
i am now removnig it from the menu in my build. 

[timofonic]

Are the plans for a new schematic? I'll try to do it in KiCad, plus the PCB. I won't promise about being good enough, it will be my first try on KiCad and I didn't do one in tons of months.

[madires]

Those diodes on paper would drop 5.0V to about 3.4 - 3.6 which would probably be OK for the display. I have one of those units (the only one to which I did not add any hardware extensions) and the voltage to the display is closer to 4.1V so I expect the display to die an early death. The diodes drop very little voltage at the current levels of the LCD. Disabling the pullups helps mitigate the potential damage to the signal lines but still is far from ideal solution and I believe that you also need to add a pullup resistor to PD0. On another unit I had (which came with a 3.3V regulator on the LCD board), I added an HC4050 to translate the 5.0/3.3 v signal levels.

The internal pullup resistors should be disabled anyway. The control/signal lines for the display are set up at startup as output (high or low, based on the defaults required). Since the rotary encoder is is parallel with two display signals, the firmware changes the two I/O pins from output mode to input mode for polling the encoder and after that back to output again. The high level for the display signal lines is 5V!

Yes, using a 3.3V LDO and a level shifter, like the 74HC4050, is the best way to connect a 3.3V display. Some displays may have 5V tolerant inputs, but series resistors (2.7k) for limiting the current might be a good advice. I've added level shifters to all the 3.3V graphic displays I use and I haven't seen any problems with a rotary encoder in parallel so far.

When the display is screwed up by the rotary encoder in parallel, one could try to add some sort of level shifting for the two display signal lines involved.

[madires]

Are the plans for a new schematic? I'll try to do it in KiCad, plus the PCB. I won't promise about being good enough, it will be my first try on KiCad and I didn't do one in tons of months.

I've started with a schematic for the ATmega 644/1284 based version. But it's going to be more like a dev-kit, i.e. it will be a modular design allowing to add different kinds of displays and hardware options. I think the main PCB will have the input protection, Zener test (30V boost converter), rotary encoder, 2.5V voltage reference, fixed self-adjustment cap, a switchable parallel cap for SamplingADC (new hw option) and a connector for additional modules (display, frequency counter, ...).

[Messtechniker]

Since I have written some PC software for the TT
- see German Site:
https://www.mikrocontroller.net/topic/248078?page=9
(search the veeeeeeeeeeeery long page for "Messtechniker") -
it would simplify matters if we could communicate via the serial
interface in both directions. i.e. RxD and TxD. Prefably SCPI style
or through a specific caommand set now that the ATmega 644/1284
provides much more memory compared to the "old" 328 the
memory of which is utilized to almost 100%.

Yours - Messtechniker

[mauroh]

it would simplify matters if we could communicate via the serial interface in both directions.

+1 
Kudos for your software!! And thank you for sharing it.
I tested it few weeks ago when you posted it on the german forum.
The only thing I wish to have on this kind of tools is to be multi-platform

I made a really simple one with processing only to use it on win and mac.
To keep the PC software stupid simple I modified the k firmware to add at the beginning of each sting sent to the serial port the number of the line and a terminator at the end of each sting.

How do you recognize the start/end of each sting/measure?
Have you implemented several conditions to distinguish the parts of the measurements?

Mauro

[gcardinal]

Thanks for this great project! Im looking for this SMD breakout - or maybe source files for it?

[mauroh]

Hi Marcus,
   I loaded the new 1.22m firmware and I'm very happy with it. Thank you!!
I kept all the optocouplers used for the previous CTR manual measurement in the same order and this is the results with the 1.22m firmware.


Model     If                     Ic                     CTR                   hFE M12864       CTR M12864
                                                                                       k firmware 656    m firmware 1.22m
PC123   0.005702985   0.006419403   112.5621565   0.92                    167
PC123   0.005704478   0.005997015   105.1282051   0.69                    118
PC123   0.005702985   0.006285075   110.2067522   0.78                    139
PC123   0.005702985   0.006316418   110.7563465   0.95                    169
PC123   0.005704478   0.006316418   110.7273679   0.83                    143
4N35    0.005704478   0.00571791     100.2354788   0.75                     132
4N35    0.005698507   0.005491045   96.35935045   0.68                     118
4N35    0.0057             0.005908955   103.6658811   0.83                     146
4N35    0.005704478   0.00569403     99.81684982   0.75                     131
4N35    0.005704478   0.005459701   95.70905285   0.65                     116
L817B   0.005689552   0.006843284   120.2780693   1.33                     234
L817B   0.005704478   0.006934328   121.559393     1.31                     224
L817B   0.005685075   0.007050746   124.022053     1.25                     208
L817B   0.005698507   0.006953731   122.0272394    1.25                    211
L817B   0.00568806     0.007010448    123.2484912   1.11                    173
4n33                                                                                                          1724
4n33                                                                                                          2261
4n33                                                                                                          1892
4n33                                                                                                          1463
4n33                                                                                                          1681
4n33                                                                                                          1806

The only issues (things I don't like but not actual bugs) I found so fare are:

1)
For the ESR measurement you selected the test poits 1 and 2 while on the k firmware are 1 and 3
My issue is that on the M12864 I can't use the banana plugs anymore to perform the measures, because this are connected to TP1 and TP3
My main use of the banana plugs are with the tweezers that are really useful

2)
I keep the TT inside my bag and I find it always on.
On the display I found "done!" or "No component found!" and it stay there forever.
Also turning the encoder to enter the menu, after I select Exit it appear "done!" but it stay there forever.
 
I replicated the issue pushing the encoder during a measure without components and instead of perform 5 measure and than power off it stops at "No component found!"

Mauro

[madires]

it would simplify matters if we could communicate via the serial
interface in both directions. i.e. RxD and TxD. Prefably SCPI style
or through a specific caommand set now that the ATmega 644/1284
provides much more memory compared to the "old" 328 the
memory of which is utilized to almost 100%.

The ATmega664's PD1 (TXD0) is already assigned for serial output and PD0 (RXD0) is unused. You're not the only one with an idea about a bidirectional serial port (possibly a serial2usb adapter). So we could try to add some sort of command set for control and reading results later on.

[Messtechniker]

The only thing I wish to have on this kind of tools is to be multi-platform #

On platforms other than Windows you'd have to use an emulator like "Wine", for example.

I made a really simple one with processing only to use it on win and mac.
To keep the PC software stupid simple I modified the k firmware to add at the beginning of each sting sent to the serial port the number of the line and a terminator at the end of each sting.

Also throught about doing this. But decided instead inspite of the parsing difficultires
to stay compatible with the standard firmware. You might ask Kubi in the
German forum to include your fimware mod in the k firmware.
I would then adapt my progs accordingly.

How do you recognize the start/end of each sting/measure?

I simply select a suitable (unique) character in the string to split it for further
string processing. Certainly not ideal because I am forced to used different
splitting characters depending on the type of component.

Have you implemented several conditions to distinguish the parts of the measurements?

No. Is too diffucult or impossible when simply relying on what the Transistor Tester
currently spits out. Hence my request for duplex serial communication for the larger ATMEGAs.

Therefore wrote separate progs for each component. Currently these progs are
BJT, JFET, MOSFET, OPTO and RES. The prog CAP for capacitors being the last on my list
will be available soon. Still needs to simmer a bit.

Yours - Messtechniker