$20 LCR ESR Transistor checker project

[madires]

Do you mean that the firmware is using PC2 as output for the collector current?
PB0 for the Led current trough R1 680 and you are reading the voltage on PC1 to calculate the current on the emitter?
The difference between If and Ie will give us Ic to calculate the CTR...

The pin numbers are relative The firmware uses the ADC port pin which it thinks it's the collector and sets the pin to output mode and high level. Yes, the LED's current is measured using R1 as a current shunt, but the relation between If and Ie is the CTR.

Again I think this is what I'm missing:
Do you mean that the firmware is using PC2 as output for the collector current or we need to remove R3 on my diagram that means R5 on the M12864 schematic??

Yes, and R2 and R3 are both disabled. Anyway, there's still the resistance of the MCU's pin driver which is around 20 Ohms. That internal resistance is measured by the self-adjustment and considered where it matters. In the case of the CTR measurement the internal resistance (R3) is used a current shunt. Since it's facing Gnd it will give us the benefit of a low voltage below the internal bandgap reference, i.e. we get an ADC resolution of 1mV instead of the standard 5mV (5V Vcc used as reference).

[mauroh]

Ok, now it make sense 

I measured some darlingtons with VLed=VC=5V, RLed=680, RE=0 and RC=20. (cathode and emitter shorted)
This is what I got:

Model   If                   Ic           CTR                    hFE M12864
4N33   0.005722388   0.085   1485.393845   7.64
4N33   0.005679104   0.0825   1452.693824   5.98
4N33   0.005697015   0.1065   1869.400052   10.3
4N33   0.005695522   0.0895   1571.409853   7.34
4N33   0.005725373   0.088   1537.017727   6.54
4N33   0.00571791   0.0875   1530.2793   7.15

With the same setup I measured also a 4N35.

Model   If                   Ic           CTR                    hFE M12864
4N35   0.005714925   0.009   157.4823714   0.83

This one with RC=680 gave me a CTR of 110

Mauro

[madires]

I measured some darlingtons with VLed=VC=5V, RLed=680, RE=0 and RC=20. (cathode and emitter shorted)

Thanks for the additional measurements!

With the same setup I measured also a 4N35.

Model   If                   Ic           CTR                    hFE M12864
4N35   0.005714925   0.009   157.4823714   0.83

This one with RC=680 gave me a CTR of 110

The common collector hFE measurement also uses RE=680 Ohms (shared with the LED's cathode). That's why the hFE has to be taken with caution. Another point to remember is that the CTR has a non-linear relation to If. The CTR has a peak at some If and also changes with the ambient temperature. Lot's of fun

[mauroh]

The common collector hFE measurement also uses RE=680 Ohms (shared with the LED's cathode). That's why the hFE has to be taken with caution. Another point to remember is that the CTR has a non-linear relation to If. The CTR has a peak at some If and also changes with the ambient temperature. Lot's of fun

Yes, that's why I played a bit with LTSpice, plotting the curves to verify the expected CTR with my setup.
It was really easy to slightly change the CTR just placing a finger on the component during the measurements
Since for the darlingtons test, current is quite high and the component self heat a bit, I left the components settle for few seconds to have a stable reading.

Yes it was fun

Mauro

[luma]

Hi! I have already realized your offer. You can look at result. Thanks!

Wow man, that's very helpful.  Thanks for making this happen, this resource will be useful for a beginner like me!

[upsss]

Hi, I need some help.  I have one of this testers, I wired to it a rotary encoder with a programmer and I am trying to reflash it. 

I found here this firmware called mega328_st7565_kit and my understanding was that it is the latest firmware with the encoder enabled.  The flashing goes smoothly without any problems.  However, the tester doesn't work, I have blank screen. 

I guess this firmware is wrong.  Can someone please provide a link for the correct firmware with the rotary encoder enabled.

Thanks

[gorgamin]

Hi, I need some help.  I have one of this testers, I wired to it a rotary encoder with a programmer and I am trying to reflash it. 

I found here this firmware called mega328_st7565_kit and my understanding was that it is the latest firmware with the encoder enabled.  The flashing goes smoothly without any problems.  However, the tester doesn't work, I have blank screen. 

I guess this firmware is wrong.  Can someone please provide a link for the correct firmware with the rotary encoder enabled.

Thanks

Check the guide by tom666 here:

https://www.eevblog.com/forum/testgear/lcr-t4-mtester-v2-07-lcr-meter-black-block-issue/

Use the "Flash K-version (v1.12kr647)" firmware.


Can I ask for a schematic and part number of the rotary encoder you used?

Let me know how it goes^^

[upsss]

@gorgamin, I am getting closer.  I flashed my tester with firmware v1.12k_r453_EN and now my tester is working (v. 1.12k) but the rotary encoder still doesn't work.  I don't know if this version has the encoder enabled or not.  Do you have a link for the v1.12kr647 firmware?  Does anyone has a link to firmware version that the encoder is enabled?

This is the encoder I am using http://www.aliexpress.com/item/Rotary-Encoder-Module-Brick-Sensor-Development-for-arduino-Dropshipping-KY-040/32598943217.html, I just removed it from the board it came with and mounted it with the required resistors on my tester.

[upsss]

@Tom666 Hi,

I updated my tester with firmware v1.12k_r453_EN I found in one of your earlier posts here and it seems to work great.  Now I am trying to add a rotary encoder to it as you can see in the pictures above.  I am wondering if you have a complied version of this firmware with the rotary encoder enabled.  In any case, I would like the Makefile for it so I can play with it and learn how to compile it myself with some other changes.

Thanks

[tino_so]

I am also thinking of adding an encoder to one of the testers I have. I found some pre-compiled versions here, I think most would have the encoder available by default:

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

One can use the "download tar ball" link at the bottom of the page to get the code, so you can brew your own, or drill in to one of the folders that have a version that may match your hardware, all ready to go and try to load it with avrdude, to see how it works.

This is the project page:

http://www.mikrocontroller.net/articles/AVR_Transistortester

[upsss]

I tried several of the compiled firmware version from that archive, my tester worked but not the rotary encoder.  If you find any of the compiled firmware that works with this LRC-T4 tester and the encoder, I would appreciate to know which one worked.

[tom666]

... I am wondering if you have a complied version of this firmware with the rotary encoder enabled.  In any case, I would like the Makefile for it so I can play with it and learn how to compile it myself with some other changes.

Try this freshly compiled version (rotary encoder is enabled on the ports PD1 and PD3):

[tom666]

Can I ask for a schematic and part number of the rotary encoder you used?

See attached picture from the official manual.

Rotary encoder can be purchased on eBay:
http://www.ebay.com/itm/141887440223

[upsss]

... I am wondering if you have a complied version of this firmware with the rotary encoder enabled.  In any case, I would like the Makefile for it so I can play with it and learn how to compile it myself with some other changes.

Try this freshly compiled version (rotary encoder is enabled on the ports PD1 and PD3):

Hi Tom, thanks a lot! Works perfectly now!!!

[klaus11]

I mounted version 659 - 7565 kit and will not work now does not work with the previous fw 627.

[madires]

I mounted version 659 - 7565 kit and will not work now does not work with the previous fw 627.

Which clone do you got? Which firmware version was running before?

[klaus11]

 mega328_st7565_kit/ Rev 659.
Rev627 had before install new Rev659 and now nothing works




Buffer Rev.659

Buffer content from address: 00000000h, to address: 0000010Fh
Address        +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F   0123456789ABCDEF
-------------------------------------------------------------------------------
0000000000 2D C6 00 00 3D C6 00 00 3B C6 00 00 39 C6 00 00     -Æ..=Æ..;Æ..9Æ..
0000000010 37 C6 00 00 0C 94 1D 27 33 C6 00 00 0C 94 B0 0C     7Æ...”.'3Æ...”°.
0000000020 2F C6 00 00 2D C6 00 00 0C 94 3F 1D 0C 94 01 27     /Æ..-Æ...”?..”.'
0000000030 0C 94 0F 27 0C 94 19 1D 23 C6 00 00 21 C6 00 00     .”.'.”..#Æ..!Æ..
0000000040 0C 94 DB 26 1D C6 00 00 1B C6 00 00 19 C6 00 00     .”Û&.Æ...Æ...Æ..
0000000050 17 C6 00 00 0C 94 B1 0C 13 C6 00 00 11 C6 00 00     .Æ...”±..Æ...Æ..
0000000060 0F C6 00 00 0D C6 00 00 B2 00 A9 00 A0 00 10 08      .Æ...Æ..².©. ...
0000000070 40 7E 01 01 3E 01 01 3E 01 01 3E 01 01 7E 40 40      @~..>..>..>..~@@
0000000080 18 00 07 20 08 08 08 F8 00 00 00 20 60 A0 3F A0       ... ...ø... ` ?
0000000090 60 20 02 02 02 FF 02 02 02 10 10 10 1F 00 00 00       ` ...ÿ..........
00000000A0 07 08 FF DB BD B5 B5 CB FF 07 08 FF BB 9D AD AD       ..ÿÛ½µµËÿ..ÿ»--
00000000B0 B3 FF 07 08 FF FF F7 FB 81 FF FF 10 10 05 08 F8          ³ÿ..ÿÿ÷ûÿÿ....ø
00000000C0 78 38 58 88 09 10 03 08 1C 3E 7F 0D 08 07 10 FF      x8Xˆ.....>.....ÿ
00000000D0 81 81 81 F1 E1 C1 FF 40 40 40 47 43 41 0D 08 01      ñáÁÿ@@@GCA...
00000000E0 10 FF FF 11 08 03 10 F1 E1 C1 47 43 41 0E 00 08      .ÿÿ....ñáÁGCA...
00000000F0 20 21 21 12 20 60 E0 E0 E0 FE FE 04 02 01 00 01      !!. `àààþþ.....
0000000100 03 7F 7F 21 C2 C4 C4 C0 40 94 84 00 07 03 01 02     ...!ÂÄÄÀ@”„.....

Buffer Rev. 627

Buffer content from address: 00000000h, to address: 0000010Fh
Address        +0 +1 +2 +3 +4 +5 +6 +7 +8 +9 +A +B +C +D +E +F    0123456789ABCDEF
-------------------------------------------------------------------------------
0000000000 74 72 61 6E 73 69 73 74 6F 72 74 65 73 74 65 72        transistortester
0000000010 2F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       /...............
0000000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
0000000030 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
0000000040 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
0000000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
0000000060 00 00 00 00 30 30 30 30 37 35 35 00 30 30 30 30       ....0000755.0000
0000000070 30 30 30 00 30 30 30 30 30 30 30 00 30 30 30 30      000.0000000.0000
0000000080 30 30 30 30 30 30 30 00 31 32 36 35 31 33 35 36      0000000.12651356
0000000090 32 34 36 00 30 30 31 35 33 36 36 00 35 00 00 00      246.0015366.5...
00000000A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
00000000B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
00000000C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
00000000D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
00000000E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
00000000F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00       ................
0000000100 00 75 73 74 61 72 00 30 30 76 69 65 77 76 63 00       .ustar.00viewvc

[jayesjay]

I'm desperate! How can I reset the display contrast? The screen lights up, but the contrast is nil so no characters appear - the checker is now useless.

I have an implementation of the transistor checker with one push button - it was working fine until I played with the contrast control. It went down through 38 or so, and now there is no display of black characters on the bright screen.

I have tried disconnecting the battery for several minutes. Pressing the button after reconnecting, the display is unchanged.
I apologise if I have hit the wrong forum, or thread, but I am new here, it's a big forum, and I am desperate!

[madires]

mega328_st7565_kit/ Rev 659.
Rev627 had before install new Rev659 and now nothing works

Could you please a little bit more specific. Is the LED lit when powered on? Does the display show anything?

[madires]

I'm desperate! How can I reset the display contrast? The screen lights up, but the contrast is nil so no characters appear - the checker is now useless.

Several posts ago there's a recipe to enter the contrast menu. Otherwise you can flash a new firmware (will set the contrast's default value).

[klaus11]

mega328_st7565_kit/ Rev 659.
Rev627 had before install new Rev659 and now nothing works

Could you please a little bit more specific. Is the LED lit when powered on? Does the display show anything?

Yes Led powerd on, shows hundreds of scribbles

[jayesjay]

Thanks for prompt response.

The display lights up, as normal when test button is pressed. The characters on the screen, which should be "black" are missing as the contrast has been adjusted, in error, to be very low.

This happened when I tried out more functions (component test) than I normally use via the display.
I pressed the test button to get the menu. Scrolled down with short presses to get to contrast, and then a long press to activate this.
A number appeared, something like 38. I pressed the test button and noticed that the number changed one way, I can't remember if it increased or decreased only by 3 or 4 and the contrast suddenly went from OK to nil.

In vain I tried disconnecting the battery and leaving the module for a while. I don't think that would help as I assume some digital word has been set in memory.

As I had taken a note of the menu items, I have tried the long press, so the menu should be there, and short pressed to hopefully arrive at the 9th item, contrast, on that menu. But since I don't know how the test button is used to make the contrast adjustment. I can't see how that can help.

I don't think I have the capability to revamp software, although I could do simple things like shorting a pin.

The forum is telling me I have two new posts to read, but I can't see how to get to them, so I will post tghis anyway.

[jayesjay]

I've done some more testing. I noted the results of a search which brought up some ideas - basically either re-flashing firmware - no, I can't go down that route - or trying to locate the contrast item in the menu by trying presses. I have done that, but with no result.
 According to my list, the menu items are, when enabled on the display: MENU/Switch off/Transistor/Frequency/F-generator/10-bit.../C+ESR.../Rotary encoder/Selftest/Contrast/Showdata/switch off.....

Further, in the absence of a convenient scope (big one upstairs!), I put a amplifier input across pins 1 and 2, (line in) and listened to the sound as I went through the menu. I got a series of short burps for each menu position, and no tones which I hoped would be output at the appropriate menu item. Or are they out of the audio range?  I would expect output signal after one long press/ 3  and 4 short presses, (and contrast after 4 more short presses.

Considering a new unit is less than £10, it's got to the stage where maybe it isn't worth any more effort. I really don't need the item, I bought it as it is a nice item for its price.

[Godzil]

I've bought one of the chinese clone with a case and I'm really happy with it, just for the fun, I may try to add French as a language in the code repository..

Oh and I've notices a funny misspell in the chinese case warning about caps: "

"Attention: Allways be shure to discharge capacitors"

and instantly though, haha Chinglish is always so fun, unless I see the original and official documentation of the tester... To find that they cut and past that from this documentation

I don't know who to tell, but the documentation is full of "shure". I'm not sure that it's correct... (it should be corrected)

[jayesjay]

My son says he can flash the firmware - he has the gear. Where can he get  the program from?