$20 LCR ESR Transistor checker project

[madires]

Makes somewhat sense. The forward breakdown happens at about 7 V which is too high for the tester's 5 V. Below the breakdown voltage there's nearly no current. But in reverse mode there's some current flowing, causing the tester to see a PNP.

[Feliciano]

Yes, I was thinking on the same reason. Nevertheless I got curious about how it would be identified by the m-firmware, and it detects a PUT (closer to the real thing, I think, so, good job, friend). I'm updating my previuos post with your firmware reference.

[ricktendo]

I have a few questions, I have a Fish-8840 that I have made the battery drain fix/mod, added pin header and a DC power jack:

- I would like to know what firmware I should use? (mega328_fish8840 vs mega328_fish8840_OC vs FishTesterOC)
- Should I update the crystal from 8 to 16?
- If I do upgrade the crystal do I have to recompile the firmware for this upgrade?

Note: I do not plan on doing any further hardware mods, other than maybe upgrade the crystal oscillator (depending on what you guys advise)

[madires]

- I would like to know what firmware I should use? (mega328_fish8840 vs mega328_fish8840_OC vs FishTesterOC)

Please try mega328_fish8840_OC. The OC is meant for driving 3.3 V displays without any level shifting or resistors in the signal lines.

- Should I update the crystal from 8 to 16?

The higher frequency helps a little bit with some measurements. It's up to you.

- If I do upgrade the crystal do I have to recompile the firmware for this upgrade?

Yes.

[ricktendo]

Anybody have any idea what would cause this, no matter what firmware I flash (mega328_fish8840_OC, FishTesterOC, mega328_fish8840 or Original) I get this screen display

I used Teensy++ 2.0 with ArduinoISP and AVRDude cli v6.3.1.1 with the following commands

Code: [Select]

avrdude –C avrdude.conf –c avrisp –P COM5 –b 19200 –p m328p -U eeprom:w:mega328_fish8840_OC.eep:i
avrdude –C avrdude.conf –c avrisp –P COM5 –b 19200 –p m328p –U flash:w:mega328_fish8840_OC.hex:i
avrdude –C avrdude.conf –c avrisp –P COM5 –b 19200 –p m328p -U lfuse:w:0xff:m -U hfuse:w:0xd9:m -U efuse:w:0xfc:m
I also tried restoring my original backups and reset the fuses to what they were previously and same problem with the screen, could it be that I scrambled something on the LCD?

Edit: After browsing the forum I found AVRDUDESS gui and with this I was successfully able to flash my device. I did have to compile my own to FLIP LCD vertical, but other than that all good!

[Yuriy_K]

Edit: After browsing the forum I found AVRDUDESS gui and with this I was successfully able to flash my device. I did have to compile my own to FLIP LCD vertical, but other than that all good!

You can try this firmware,I did for my tester with the same display. If you set the crystal to 16 MHz, you can get additional functions. This firmware is for 8 MHz quartz.

[ricktendo]

A feature I think would be a nice inclusion to this Swiss army knife of a device is a thermometer (similar to the FG-100) to calibrate soldering iron tips

I do not know if it would require a new PCB, or if it could simply be implemented in existing boards like the GM328A (maybe calibration would be too difficult )

[madires]

For a thermocouple you'll need a frontend plus cold junction compensation. If someone knows a suitable IC for that we might be able to add such a hardware option.

[Feliciano]

As a first thought, it could be the typical K-thermocouple sensor of a DMM, connected to an opamp (or to an instrumentation opamp for better accuracy) converting those few mV to something less than 5V for a component tester to measure. That way you could adjust software parameters to match the slope and offset. Attached one example of such basic circuit.

Or to your exact question, an improved circuit is integrated into AD595 (or the newer and smaller AD8495) and would allow direct connection to an ATmega (and there is also a C-code for that interface on the web).

[ricktendo]

Does the type of capacitor I use for calibration matter?

Can I use ceramic capacitors, what about electrolytic and smd?

[Vitaly_Ne]

"Film capacitor" usually refers to a polyester or polymer film as a dielectric - as another answer points out, metallized film capacitors are the same thing: a metal coating applied over an extremely thin polymer film to create conductive electrodes for the capacitor.

In general, ceramic capacitors are somewhat non-linear in their frequency and voltage characteristics when compared to film capacitors. Another (very minor) problem with ceramic capacitors is that they tend to behave like microphones, thus picking up ambient sound and modulating the voltage across them accordingly...

[Yuriy_K]

Can I use ceramic capacitors, what about electrolytic and smd?

No, you must use capacitors with the smallest Temperature Coefficient of Capacitance.

The message \1-||- 3 >100nF" is shown in row 1 of LCD. To prepare the measurement of the comparator oset
voltage, you must connect a sucient big capacitor to pin 1 and pin 3. It should be a capacitor
with a high quality factor and a capacity between 100nF and 20F. You should never use
electrolytical capacitors, use lm capacitors instead. (Clause 5.5 page 119)

TransistorTester with AVR microcontroller
and a little more
Version 1.13k
Karl-Heinz Kubbeler
kh kuebbeler@web.de
March 8, 2018

[morgan_flint]

As a first thought, it could be the typical K-thermocouple sensor of a DMM, connected to an opamp (or to an instrumentation opamp for better accuracy) converting those few mV to something less than 5V for a component tester to measure. That way you could adjust software parameters to match the slope and offset. Attached one example of such basic circuit.

Or to your exact question, an improved circuit is integrated into AD595 (or the newer and smaller AD8495) and would allow direct connection to an ATmega (and there is also a C-code for that interface on the web).

There are also ready-made modules based on MAX31855 or MAX6675 with cold junction compensation and digital output (I2C) for a few dollars, for example this one, that could be used as an add on for this purpose

[ricktendo]

OK so lets say I have the following value film caps:

100nF, 150nF, 220nF, 470nF (for 1-||- 3 >100nF test)
10nF, 15nF, 22nF, 33nF (for 1-||- 3 10-30nF[L] test)

Which value would you recommend I select for calibration?

[indman]

Which value would you recommend I select for calibration?

There is no need to invent anything, everything is described in detail by the author of the manual. It is necessary to use those ratings that are required for the calibration and it does not matter what particular value of capacitance from this range is used.

[Yuriy_K]

OK so lets say I have the following value film caps:

1   100nF, 150nF, 220nF, 470nF (for 1-||- 3 >100nF test)
2   10nF, 15nF, 22nF, 33nF (for 1-||- 3 10-30nF[L] test)

Which value would you recommend I select for calibration?

I have highlighted the capacity that I use. For the first point, the capacity value is not significant. On the second point, in addition to the value of the capacitance, the quality factor of the capacitance plays a significant role. He showed with an example in the photo how to select capacities according to the value of the figure of merit - the highest Q.

[madires]

There are also ready-made modules based on MAX31855 or MAX6675 with cold junction compensation and digital output (I2C) for a few dollars, for example this one, that could be used as an add on for this purpose

The MAX6675 looks promising as it supports a Vcc of 3.3 and 5 V. So we could wire it in parallel with the display's SPI and only need an additional I/O pin for /CS.

[Vitaly_Ne]

Yury_K, In the firmware (ST7735_BGR_en_2.zip) I made a correction of -2% in the "C (𝜇𝐹) -correction" item, so it seems to me more accurate in my copy. For some reason, this item only allows you to deposit from + 9.9% to -2% ... less than -2% already jumps back in a circle.
The instruction says "... You can set the amount of this correction with the C_H_KORR parameter in the Makefile ....". There is an inverse relationship - if in plus - then the value of the capacity shows less, in minus - the value is greater. I need to make a minus amendment.
I can't recompile your version of the firmware.
Could you build the same firmware with this one change (leave everything else as it is)?
I found this place in the Makefile in the picture ...
Thanks.

[Yuriy_K]

Could you build the same firmware with this one change (leave everything else as it is)?

Don't understand what prevents you from setting the desired value in the menu and saving this value for further work?
If you need to decrease the readings, the correction is positive.
Read the manual ... (it is in Russian)

[Vitaly_Ne]

Yury_K , yes, I know that ... I am doing this now.
But ... it is no longer possible to reduce it even more ... that is. -2.1% ..- 2.5% - cannot be put ...
And since these percentages can be registered programmatically, I thought, if you write down -2% in the code at once, then then I will have a "reserve" and through this item you can add extra ...
Those. already programmatically will be laid (-2%) and, if necessary, I can add something to the minus ...
I just measured a lot of capacitors and made sure that (in my copy) a -2% correction for almost all capacitors is suitable (I measured electrolytes from 2μF to 10000μF). And it ranges from (-2%) to I think about (-3%) ...
It's just that you won't be able to recompile yourself, you wrote that you have the source code slightly corrected from the original ..

p.s. the adjustment range is now from -2% to + 9.9%.
If you do not immediately "sew" (- 2%), can you expand the adjustment range?
Let's say from (-10%) to (+15%) ... or at least from (-5%) ...

[Yuriy_K]

Yes, I know that ... I am doing this now.
But ... it is no longer possible to reduce it even more ... that is. -2.1% ..- 2.5% - cannot be put ...

Show with a specific example what you need.
I have a polymer capacitor with an inscription of 1500 uF having a real capacitance measured by MS5308, 1608 uF has a correction value of +3.2. If I set it to -2.0, then I get 1692 uF ...

[Vitaly_Ne]

Show with a specific example what you need.
...

for example, a 4700mkF capacitor.
In reality, his capacity is about 4350-4400μF (a friend measured it with a more accurate device). My RM219 also shows about 4300μF.
And the tester, even with a correction (-2%), barely reaches the pre-actual capacity ...
And the opportunity to make an amendment at least (-2.5% or 3%) - NO, alas ... So I asked if you could programmatically set (-2%) and then the range of adjustments would expand (by Minus).
It would have been already (-2%) initially and I could add up to (-2%) through the menu, which in the end would give (-4%), i.e. the minus range would widen ...

in the end, to make it possible to make an amendment at least from (-5%), and not from (-2%) as it is now done in the device ...
---------
range of corrections in the tester:
"+" up to 9.9%
"-" up to -2% ... but I would like up to -5% .. -10% ....

[Yuriy_K]

for example, a 4700mkF capacitor.

Take a look at my example.
To clarify: The readings on different measuring instruments differ due to the measurement methods. For Ttester, you still need to take into account the "auto-correction", look at the second and third photos. The fourth photo shows MC5308 readings. And now the question - What is considered the correct reading for a given capacitor?

Try to reduce the voltage of the stabilizer to 4.995-5.000v and power it from a stabilized source of 9-10v ...

[wandows]

Hello everyone!

My AY-AT was damaged by not discharging the electrolytic capacitor.

The firmware on the new MCU has some issues:
     ** Very slow (2 minutes to read a 1uF ceramic capacitor);
     ** Does not accurately read components;
     ** 10 minutes to perform the self-test;

The second photo shows the reading of a 67.63nF ceramic capacitor, but the correct capacitor value is 1uF.

Could any friends help me to solve this problem?
Thanks

[Vitaly_Ne]

....And now the question - What is considered the correct reading for a given capacitor?

Yes, all readings are correct.
Just measurements at direct or alternating current or another frequency - most likely differ ...
For household crafts, the accuracy of the multimeter is quite satisfactory and I would like the tester to match them as much as possible.
Compared to you, I have little experience and knowledge in this area, and I will not even try to prove something and argue or philosophize - which is more correct, at what frequency .. at what current, etc. really correct value ...)))
And not many have professional devices.
In your photo, the readings of the multimeter and testers practically coincide, so I would like to achieve this.
Even with (-2%) correction, my tester falls short of the error range.

It measures resistors, transistors, diodes very accurately (less than 5% error), which is quite satisfactory even with this power supply and parts inside, but with capacitors the nuances are ...

Try to reduce the voltage of the stabilizer to 4.995-5.000v and power it from a stabilized source of 9-10v ...

I just thought that it is not very difficult to change one number in the file ... it would be quite suitable for my needs.
The option with replacing the power supply, I will take into account, if it really does not work out with recompilation, but this is as a last resort ...

Suddenly, you still have time and without replacing the parts you will be able to solve the problem