$20 LCR ESR Transistor checker project

[madires]

Yes, a "previous (stable) value" could work. I wonder if there might be an issue (software wise) to recognise the last previous value. I mean removing the probes produces more measurements, just the values are usually very small and normally no ESR is shown. So maybe the lack of ESR could be used?

Might be an idea!

[madires]

Another question (sorry). Is there a schematic for what the tester expects as front-end for the Ring Tester (probes) option? I looked at Bob's Basic Ring Tester and its a whole standalone tester by itself. Obviously the counting and pulse gen is done by the ATMEGA but what else from Bob's circuit is needed?

Please see https://github.com/madires/Transistortester-Warehouse/blob/master/Hardware/RingTester-Option.pdf.

[Feliciano]

Thanks indman for developing those symbols.

I think they are easy on the eyes, specially the bold ones.
I notice they are rectangular on the picture you kinldy shared, I'm not sure if it's because the different resolution on X and Y, and/or aspect ratio of the screen or something else, so just to confirm: It will be seen somehow square when displayed on the actual screen?
On the other hand, I also notice the SCRs are narrower than the rest, therefore it's just a matter of tastes, but you could move the G a little bit to the left on those. And on the same line of thinking, you could move the B of the BJTs a little bit to the right.

Whatever you decide, it will be very welcome.

[madires]

I think I should add some background info about what's going on with the symbols. The next version will have an option to place the probe numbers in an alternative way. Currently the probe numbers are placed left and right of the symbol. The new option will move the right-hand numbers above and below the symbol (and the symbol is moved to the right). A new positioning flag can place a probe number in the mid (old: only top/bottom). This will make the fancy pinout easier to read for some folks. And we'll also have an option for a question mark symbol when no component was detected. This is accompanied by indman working on additional symbol sets.

[indman]

On the other hand, I also notice the SCRs are narrower than the rest, therefore it's just a matter of tastes, but you could move the G a little bit to the left on those. And on the same line of thinking, you could move the B of the BJTs a little bit to the right.

You have very good eyesight, congratulations on that! When you work with similar images of symbols for a long time, your eyes get tired and you can miss important details. That's why I decided to get your opinion on the new styles in symbols.
I will arrange the letters G and B as you noticed. As for the slightly narrow SCR symbol, this is due to the fact that the letters A and C are slightly larger in size. But I will reduce their size a little and make the symbol larger and the same as in the thin set.

[Feliciano]

Indeed several set of eyes can discover more than just one.

If you are going to resize/move letters, I think your standard is 1px of separation between text and lines, but in some cases you have 2 vertical or 2 horizontal. And there is a "1" extra-bold on the bottom-left UJT.

[indman]

And there is a "1" extra-bold on the bottom-left UJT.

No, everything is fine with this  "1", it just got distorted when I made a collage of screenshots.
I've updated the symbol images so that the 2 different sets have the same symbol placement and letters placement.

[gipetto]

Hi all, first post on this forum. I have a problem with my fish8840 avr transistor tester from 2014-07, I powered it on but the lcd screen went blank. then i peered between the pcbs and realised an offcut of wire had got in and shorted stuff out. i guess there are burned pins now. would isp flashing bring it back to life?  most likely not i assume.

[madires]

Welcome! First check the power supply section (should output 5V when the test button is pressed). Then connect an LED to the probes and check if it's blinking.

[gipetto]

I checked the voltage at the isp header and i get 4.97 volts. i plugged in the led at 1 and 3 on the socket and it does blink.

[madires]

In that case the LCD and/or the MCU pins driving the LCD could be damaged. Do you have a logic analyzer or scope?

[gipetto]

I have neither, and if I did i would have no idea how to use them. iirc there was a mode where the transistor tester could report readings over a serial terminal. maybe that could be used to test the mcu, bypassing the lcd.

[madires]

Yep, serial output is an option. In case you want to replace the LCD, the monochrome LCD is a ST7565 and the color LCD a ST7735. Both are inexpensive and easy to get.

[indman]

Hi all, first post on this forum. I have a problem with my fish8840 avr transistor tester from 2014-07, I powered it on but the lcd screen went blank.

Show a picture of your display from both sides. In this clone, the display can be quickly separated from the main board.
You need to check if +5V power is supplied to the display and if the 3.3V regulator is OK

[gipetto]

I am getting 5v on the lcd header and when i soldered a wire to the 3 pin regulator behind the lcd i got 3.293v on it so it seems to be ok. when i say the lcd is blank i mean that there is a backlight but nothing shown on screen.

[indman]

From the photo I can see that your clone is in poor condition with dust, dirt and flux residue everywhere.
First you need to wash off all the dirt and inspect the boards for broken printed circuit conductors. Also, I do not exclude the possibility that there is a breakage in the cable that connects the display to the main board.

[gipetto]

I think i have a 1602 lcd around here. do you know how to wire it up.

[indman]

gipetto, see
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg3678982/#msg3678982

[gipetto]

thanks. the wiring is different. i think i'll call it quits.

On an unrelated subject i have made a mechanical keyboard with atmega328p. some related keyboards also support ssd1306 lcd for useful features like tamagotchi. I had an idea to make a keyboard that could work as an avr transistor tester, since they both use much the same hardware. would a psu usb 5v be stable for component measurements? I could use an atmega32a to free up more pins. I don't think both transistor tester and keyboard firmware could fit at the same time though, nor would i be able to handle coding. i guess a jmp instruction could select between firmwares, if both were appended in a text file.

[taste_tester]

Is anyone using this alternate firmware on "Bside ESR02 Pro"?? and any mods needed besides  16mhz for this one?

[madires]

The BSIDE ESR02 Pro runs fine with k and m-firmware without any mods (it comes with the k-firmware). Of course you can improve the tester if you like.

[GGMM]

Hello,

I put this kit together. It works very well. (Menu access)
It’s powered by a 9v rechargeable battery, and I don’t understand why the P6KE6v8 component is so hot.
When I look at the diagram, it is directly connected from the VCC to the ground.
I think the VCC is the 9V, so if I’m not mistaken it may be in protection It’s a 6V8 model i think!
Component that has no cabling direction, so no error.
Tell me if I’m wrong about the value of the VCC, or if there’s anything else to see.
Or don’t  look correctly the schématic?? Lol?
thank you

[madires]

Vcc is 5V (5V voltage regulator). There are two versions of the TVS, one is unidirectional (P6KE6V8A) and the other bidirectional (P6KE6.8CA). For the unidirectional the polarity matters.

[GGMM]

Hello madires,

Thanks for your answer

On the file I downloaded, I was looking at page 20
there is no indication of VCC behind the regulator.!!
On the other hand, another diagram, page 10, where the VCC is indicated in output of the regulator.
Is this the latest version? If there’s anything better, I’ll take it.
I’m gonna check my clone’s circuit, maybe he’s got a mistake??
To see.
See in attached  the last file I downloaded. If best version, thank's to share.
cdt

[madires]

You'll find the latest version of Karl-Heinz' excellent documentation at https://github.com/kubi48/TransistorTester-documentation.