Author Topic: $20 LCR ESR Transistor checker project  (Read 3408902 times)

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Offline bitseeker

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Re: $20 LCR ESR Transistor checker project
« Reply #3175 on: January 23, 2017, 10:10:33 pm »
Interesting. I don't see any photos in his post. Maybe they're linked from elsewhere, not uploaded to the forum.
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Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3176 on: January 23, 2017, 10:46:10 pm »
Now that you mention it... The image is loading for me from postimg.org.
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #3177 on: January 24, 2017, 12:43:47 am »
I replaced the 7550 regulator in my ST7565 kit tester with a MCP1702 precision regulator, which is more precise than the included TL431 reference.

What should I do now? Remove the 431? disconnect pin PC4 altogether? Or is it enough just to change config.h

EDIT: I just found this in the manual: "If you don’t install the precision voltage reference and you don’t add the relay extension, you should install a pull up resistor R16 to PC4 with a higher resistance value (47k?). This helps the software to detect the missing voltage reference."
« Last Edit: January 24, 2017, 12:49:53 am by timelessbeing »
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3178 on: January 24, 2017, 11:14:43 am »
Yep, the firmware measures the voltage at PC4 and if it's around 2.5V it assumes it's the external voltage reference. The pull-up resistor makes sure that PC4 is outside the expected voltage range, and 100k or 220k would be fine also. The m-firmware behaves the same way, but HW_REF25 (config.h) controls if the code get's included or not.
 

Offline joystik

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Re: $20 LCR ESR Transistor checker project
« Reply #3179 on: January 24, 2017, 05:31:11 pm »
Hi guys.

Question: Is there a kit that uses open source firmware and capable of testing zener diodes?
Could you point me in the right direction?
 

Offline upsss

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Re: $20 LCR ESR Transistor checker project
« Reply #3180 on: January 24, 2017, 08:25:41 pm »
You can add to any of these kits a simple PWM step up converter with 28V output from eBay for less than $1.  You will also need a small MOSFET as a switch to turn it on plus a few resistors as a voltage divider, current limit and you can test Zeners up to 28v.  You can see a picture of my tester in post #3069.     
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3181 on: January 25, 2017, 06:30:10 pm »
Hi guys.

Question: Is there a kit that uses open source firmware and capable of testing zener diodes?
Could you point me in the right direction?

I'm not aware of any kits that do this, but there are ready-made testers with HV for this purpose.

As an aside, it's probably not worth trying to build a zener tester extension for this if it's not already there (although, to each his own). All you need is a power supply with high enough voltage (or even just a simple Joule Thief circuit), a resistor, and a voltmeter. Too easy, and if you have a good meter, possibly more precise, too.
 

Offline joystik

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Re: $20 LCR ESR Transistor checker project
« Reply #3182 on: January 27, 2017, 07:11:02 pm »
Thaks for the responses.

I recently got the Color M-Tester model TC-1 and connected a charged cap (by accident :-[). It wouldnt turn on, and an IC, which is unmarked, got really hot. So I opened it and unsoldered the battery(LiPo).

When I soldered it back on, it now turns on but all the tests, even with no test component, return a Cell value of 4.8 to 4.95V.
Do you think theres any hope of fixing it or should I just scrap it and buy a new one?
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3183 on: January 27, 2017, 07:15:11 pm »
For starters, remove the unmarked chip and see if the tester begins to behave again. I'm assuming it's the protection IC that we're talking about, not the microcontroller.
 

Offline joystik

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Re: $20 LCR ESR Transistor checker project
« Reply #3184 on: January 27, 2017, 07:53:39 pm »
For starters, remove the unmarked chip and see if the tester begins to behave again. I'm assuming it's the protection IC that we're talking about, not the microcontroller.

The picture shows the IC im talking about. Its marked U4. U5 also got hot, but now its fine.
I removed the IC, but the unit wont power, so i soldered back on.
« Last Edit: January 27, 2017, 07:57:03 pm by joystik »
 

Offline hapless

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Re: $20 LCR ESR Transistor checker project
« Reply #3185 on: January 27, 2017, 08:11:52 pm »
Sorry, I was thinking of another tester, one with much fewer ICs in it. In your case, (someone, please correct me if I'm wrong), looks like U1 is the problem. In other words, getting a new tester might not be a bad idea at least until you have a chip like that to replace it with and we have firmware that runs on it.
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #3186 on: January 28, 2017, 02:04:45 am »
An eBay seller sent me an HC-05 (cheap Bluetooth module for AVR, www.hc01.com/en) by mistake. I wonder if it would be possible to use it to send some output from the TT to a smartphone for display. There is an Android app specifically for using the HC-05.
 

Offline jazer

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Re: $20 LCR ESR Transistor checker project
« Reply #3187 on: January 28, 2017, 04:01:31 am »
This kind of device is handy already, and can generally sniff out an electrolytic vs. ceramic, for example (vloss and esr).

Does anybody know of a reliable means of non-destructively determining the polarity of an electrolytic, in cases where the markings are vague or lost. Any idea of that could be added to the algorithm?
 

Offline texaspyro

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Re: $20 LCR ESR Transistor checker project
« Reply #3188 on: January 28, 2017, 04:17:39 am »
Does anybody know of a reliable means of non-destructively determining the polarity of an electrolytic, in cases where the markings are vague or lost. Any idea of that could be added to the algorithm?

The traditional way to determine cap polarity it to apply the rated voltage in each direction and the one where the cap explodes is the wrong way.   >:D  but you're no fun and mentioned that "non-destructively" thing.   With the voltage and current available to the tester I doubt you can find a reliable way that would work for all caps... particularly in a reasonable amount of time.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3189 on: January 28, 2017, 03:23:15 pm »
An eBay seller sent me an HC-05 (cheap Bluetooth module for AVR, www.hc01.com/en) by mistake. I wonder if it would be possible to use it to send some output from the TT to a smartphone for display. There is an Android app specifically for using the HC-05.

I think it would be a nice idea for the ATmega 644/1284 based tester (more flash memory and a hardware serial port). With the current 328 flash is tight.
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3190 on: January 28, 2017, 03:30:19 pm »
Does anybody know of a reliable means of non-destructively determining the polarity of an electrolytic, in cases where the markings are vague or lost. Any idea of that could be added to the algorithm?

I'd gladly add such a feature if there would be a reliable method to determine the polarity.
 

Offline Housedad

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Re: $20 LCR ESR Transistor checker project
« Reply #3191 on: January 28, 2017, 05:56:23 pm »
So many revisions and makers I'm not sure which one to get.  Any recommendations?
At least I'm still older than my test equipment
 

Offline timelessbeing

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Re: $20 LCR ESR Transistor checker project
« Reply #3192 on: January 28, 2017, 08:54:57 pm »
Look around, because this is the most common question on this thread, and it's been answered numerous times.

https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg864913/#msg864913
 

Offline casinada

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Re: $20 LCR ESR Transistor checker project
« Reply #3193 on: January 30, 2017, 06:03:01 am »
It's not exactly for electrolytic capacitors :
This one detects the outside shield of the capacitor (cool)


This guy claims that his circuit detects the polarity of the electrolytic capacitor:
 

Offline mauroh

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Re: $20 LCR ESR Transistor checker project
« Reply #3194 on: January 31, 2017, 11:41:02 am »
An eBay seller sent me an HC-05 (cheap Bluetooth module for AVR, www.hc01.com/en) by mistake. I wonder if it would be possible to use it to send some output from the TT to a smartphone for display. There is an Android app specifically for using the HC-05.

On the K firmware, you just need to enable the UART on the firmware and you are good to go,see attached pictures.

I use the serial output to log some measurement and I made a small Processing sketch to display the measurements on a PC monitor.
To simplify the code, I changed the firmware to send on the UART the line number of each text string and a "new_line" = ("\r\n") at the end of each line.

I posted some detail one year ago in the following message and I hope Karl-Heinz will add this changes in the main firmware  :)
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg875362/#msg875362.
Now I fugured out how to wrap the text of the Selection menu...

If someone is interested I attached the custom firmware for the M12864 DIY Kit and the Processing sketch.
I'm also developing a small android app to log the measurements on a phone  :-+.
If you improve the Processing sketch (at the moment it can handle correctly only some of the measurements), or you are developing an app, please share it so this can become a nice addition to this super useful tool.

Mauro
« Last Edit: February 02, 2017, 09:02:00 am by mauroh »
 
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Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3195 on: January 31, 2017, 01:24:51 pm »
Awesome! I'm thinking about writing a virtual display driver which would send everything via a serial connection, e.g. a bluetooth module. It's just an idea.
 

Offline mauroh

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Re: $20 LCR ESR Transistor checker project
« Reply #3196 on: January 31, 2017, 02:55:28 pm »
Thank you Markus!!
I look forward to see this working on the m firmware  :-+
As I wrote, having the line number added to each text string sent to the UART and a fix line terminator will semplify alot all the developments of the PC/Mobile Apps.
I think should be good to have the same serial output format on the k and m firmware to use the same apps with both.
Do you know if Karl-Heinz follow this thread or I have to write in the german forum?
I know you are both really busy and doing a greate job, but I would like to know at least if he is interested in adding this changes to the main release.

Have a nice day
    Mauro
« Last Edit: January 31, 2017, 07:12:14 pm by mauroh »
 

Offline madires

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Re: $20 LCR ESR Transistor checker project
« Reply #3197 on: January 31, 2017, 03:33:27 pm »
Please send him an email with the link to your post.
 
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Offline rastro

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Re: $20 LCR ESR Transistor checker project
« Reply #3198 on: January 31, 2017, 03:48:33 pm »
Is there any way for the component checker be adapted to identify the "foil side" of an un-polarized capacitor?

It seems important to know the orientation of the foil side so it can be attached to the low impedance side to help diminish noise pickup.

This is mentioned in Mr Carlson's Lab video:


-rastro
 

Offline madcat

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Re: $20 LCR ESR Transistor checker project
« Reply #3199 on: February 01, 2017, 09:03:08 am »
i finally got some time to assembly this AY-AT tester. it was fun enough for me as soldering-newbie.  :)
but when powered it up, it didn't function normally.
after displays "turn-off, transistor & frequency" menu at first start (rotary encoder works for turn it on, but not functioning at this stage), it goes to "V-ext" measurement automatically and stays there until the power jack is unplugged.

does anyone has experienced this problem or have any clue about it?
here's some pics i took :
 


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