Author Topic: Component tester with I(U) diagram?  (Read 2332 times)

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Offline ebastlerTopic starter

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Component tester with I(U) diagram?
« on: September 23, 2024, 05:43:59 am »
Some old scopes, e.g. the Hameg HM604, have a simple built-in component tester: It applies a 24 Vpp sine voltage to the DUT in series with an internal resistor, and displays an X/Y plot with the applied voltage on the horizontal axis and the voltage over the resistor (i.e. the current flowing through the DUT) on the Y axis.

Quite handy e.g. for a quick check whether a diode still has its expected behaviour. Some in-circuit tests take a moment's thought, but the manual helps with that -- see the attached diagrams.

It's obviously possible to rig up something like this as an external scope attachment (or to get a proper curve tracer which does this with more flexibility). But I like the simple, always-ready, no-messy-cables built-in tester. Hence I am wondering:
  • Are there still (modern) scopes which offer this option?
  • Any small, self-contained gadget you have come across and can recommend? This should be easy to do with a microcontroller and small graphical display, since it does not require high sampling rate and bandwidth.
 

Offline tautech

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Re: Component tester with I(U) diagram?
« Reply #1 on: September 23, 2024, 06:42:45 am »
Some old scopes, e.g. the Hameg HM604, have a simple built-in component tester: It applies a 24 Vpp sine voltage to the DUT in series with an internal resistor, and displays an X/Y plot with the applied voltage on the horizontal axis and the voltage over the resistor (i.e. the current flowing through the DUT) on the Y axis.

Quite handy e.g. for a quick check whether a diode still has its expected behaviour. Some in-circuit tests take a moment's thought, but the manual helps with that -- see the attached diagrams.

It's obviously possible to rig up something like this as an external scope attachment (or to get a proper curve tracer which does this with more flexibility). But I like the simple, always-ready, no-messy-cables built-in tester. Hence I am wondering:
  • Are there still (modern) scopes which offer this option?
  • Any small, self-contained gadget you have come across and can recommend? This should be easy to do with a microcontroller and small graphical display, since it does not require high sampling rate and bandwidth.
Mike has a couple of threads that might be of interest:
https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/
https://www.eevblog.com/forum/projects/dso-awg-based-curve-tracer/
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Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #2 on: September 23, 2024, 08:00:53 am »
Mike has a couple of threads that might be of interest:
https://www.eevblog.com/forum/testgear/fooln-around-with-dso-awg/
https://www.eevblog.com/forum/projects/dso-awg-based-curve-tracer/

Thanks! Mike's schematic will be most helpful in case I end up building something myself. 

Mike's design is approaching the "connect a proper curve tracer to a scope externally" end of the spectrum. I was hoping that something simpler, but with a built-in display, might be available -- either as a complete product or as a documented DIY project. For a simple component tester, less control over the measurement conditions would probably be ok. (Although, compared to the old Hameg tester, one would at least want an alternate setting which applies a lower voltage to the DUT.)
 

Offline Aldo22

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Re: Component tester with I(U) diagram?
« Reply #3 on: September 23, 2024, 08:19:29 am »
You mean something like this but "built-in"?

https://youtu.be/kEuixDsiCW0?t=1413
 

Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #4 on: September 23, 2024, 08:31:54 am »
You mean something like this but "built-in"?

https://youtu.be/kEuixDsiCW0?t=1413

Yes, that's the principle. The old Hameg scopes had it built in (including a simple signal source derived from the 50 Hz supply).

I am not aware of a modern scope which includes something like this, but was hoping to find a simple gadget which includes signal source, LCD and two probe connections. Since the signal frequency is just 50 Hz (maybe switchable to a bit higher, to check small capacitors), any microcontroller with ADC and DAC should be enough for driving this.
 

Offline Aldo22

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Re: Component tester with I(U) diagram?
« Reply #5 on: September 23, 2024, 08:41:17 am »
Sounds like a very sensible and feasible DIY project, doesn't it?
If you need a portable version, buy the DSO2512G from the video.  ;)
 

Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #6 on: September 23, 2024, 08:50:42 am »
Sounds like a very sensible and feasible DIY project, doesn't it?
If you need a portable version, buy the DSO2512G from the video.  ;)

Yes, I'm tempted to add that to my project list. :)  Just had expected that it already exists and is available on Github or as a cheap complete device on ebay or whatever. This one comes close but looks a bit half-baked: https://www.alaonix.com/Ala_CT_2000.html
 

Offline Aldo22

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Re: Component tester with I(U) diagram?
« Reply #7 on: September 23, 2024, 09:03:18 am »
This one comes close but looks a bit half-baked: https://www.alaonix.com/Ala_CT_2000.html

But that looks pretty much like what you're looking for. What's missing?
 

Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #8 on: September 23, 2024, 09:14:50 am »
But that looks pretty much like what you're looking for. What's missing?

Yes, it's conceptually exactly what I was thinking of. I am missing just some finishing touches: Would prefer to have an even lower voltage range, maybe a couple different vertical amplification settings, axis labels directly on the axis (at least the horizontal one), and a  built-in battery. Since it's not an open-source design it can't be easily modified.

But it is close enough to make it a difficult decision whether it's worthwhile to roll my own...
 

Offline kripton2035

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Re: Component tester with I(U) diagram?
« Reply #9 on: September 23, 2024, 12:13:51 pm »
I'm with you on such a project ...
first problem with small portable 2 channels DSO: the XY view is really too small, it should occupy the whole screen?
 


Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #11 on: September 23, 2024, 03:03:40 pm »
Hmm, that's a nice option if one already has the right handheld scope with an AWG. Or maybe a nice excuse to get one! ;) A compact and tidy setup, but it still requires a bit of setup time to connect the box, and a few button presses to set up the AWG and the X/Y mode in the scope. So maybe a small dedicated device still makes sense?

I wish OWON had thought of including that "curve tracer mode" in the scope itself, and making it available via the regular multimeter test lead connections. I'd buy that right away!
 

Offline Evergreen64

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Re: Component tester with I(U) diagram?
« Reply #12 on: September 23, 2024, 10:52:52 pm »
Peak Electronic Design makes a tester for semiconductors called the DCA75 Atlas Pro that can do curve tracing. You have to connect it to a computer to see the curves though. https://www.peakelec.co.uk/acatalog/dca75-dca-pro-semiconductor-analyser.html
 
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Offline kripton2035

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Re: Component tester with I(U) diagram?
« Reply #13 on: September 24, 2024, 06:12:07 am »
I think the OP (and me too) are looking for a compact, portable device that does show by itself components curves.
there are already aout there lots of octopus and bulky component testers...
 

Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #14 on: September 24, 2024, 07:19:58 am »
I think the OP (and me too) are looking for a compact, portable device that does show by itself components curves.
there are already aout there lots of octopus and bulky component testers...

Yes, that's the idea. I am really tempted to build something... I like the idea of keeping this minimalistic, with just a small touch display, power button, USB charging port, and two jacks for test leads.

Does a 3.2" touch screen (320*240 pixels) sound large enough? It would only be used for qualitative "eyeballing" of curves, but should be able to display labels on the voltage axis and let you estimate diode forward and breakdown voltages.

One can always get fancy in the software, trying to recognize certain components and display rough measurement values for them. Minimal controls would be the selection of two to three voltage ranges, I'd guess: +-12V to check most diode voltages of interest, +-2V or less to avoid damaging sensitive circuits -- anything else? Are different current measurement ranges required, or different frequencies for capacitor measurements?
 

Online ch_scr

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Re: Component tester with I(U) diagram?
« Reply #15 on: September 24, 2024, 08:28:11 am »
What you describe sounds a lot like the "ELV Komponententester"
 
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Offline kripton2035

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Re: Component tester with I(U) diagram?
« Reply #16 on: September 24, 2024, 08:34:43 am »
this https://www.aliexpress.com/item/1005006160645147.html
and a small supply - battery - adc board.
and a big amount of software...
 

Offline kripton2035

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Re: Component tester with I(U) diagram?
« Reply #17 on: September 24, 2024, 08:35:22 am »
What you describe sounds a lot like the "ELV Komponententester"
yes, but this screen is too small
 

Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #18 on: September 24, 2024, 08:50:12 am »
What you describe sounds a lot like the "ELV Komponententester"

It does, and I had not been aware of that product -- many thanks!

As mentioned by kripton2035, the display is a bit small. (Reassuring me that my 3.2" idea should be big enough!) And more critically, the curve tracer seems to work with a fixed +- 10V, limiting its in-circuit use. I will take a close look at their schematics though; I'm sure I can learn a few things there.
 

Offline tautech

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Re: Component tester with I(U) diagram?
« Reply #19 on: September 24, 2024, 08:52:51 am »
I think the OP (and me too) are looking for a compact, portable device that does show by itself components curves.
there are already aout there lots of octopus and bulky component testers...

Yes, that's the idea. I am really tempted to build something...
Why ?
Do you have a 2ch AWG ?
20V capable into HiZ ?

You already have a DSO with an excellent X-Y mode.
Is the procedure Mike used insufficient for your needs ?
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Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #20 on: September 24, 2024, 08:55:36 am »
this https://www.aliexpress.com/item/1005006160645147.html
and a small supply - battery - adc board.
and a big amount of software...

Yes, that might work. But I don't see much in terms of I/O expansion headers? I might look for a microcontroller which can handle the AD/DA conversion on-chip and just requires analog amplifiers (or dividers) externally. Pure 3.2" touch displays with SPI interface are available from AliExpress as well, a bit cheaper than the display/µC combination.
 

Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #21 on: September 24, 2024, 08:57:54 am »
Why ?
Do you have a 2ch AWG ?
20V capable into HiZ ?

You already have a DSO with an excellent X-Y mode.
Is the procedure Mike used insufficient for your needs ?

As stated above, I am looking for something with less cabling, very quick to use, ideally handheld. I am not thinking of a precision curve tracer, but rather a "quick check" for components, and it should not take more time to set up than to do the actual measurement.  :)

EDIT: Having said that, Mike's design provides a great reference on "how to do this properly". I'll try to understand it and use it as a guideline, but can probably cut some corners for the limited accuracy and flexibility I am aiming for.
« Last Edit: September 24, 2024, 09:43:02 am by ebastler »
 
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Offline ledtester

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Re: Component tester with I(U) diagram?
« Reply #22 on: September 24, 2024, 10:01:39 am »
Perhaps you can get the FNIRSI 1013D hackers interested:

https://www.eevblog.com/forum/testgear/fnirsi-1013d-100mhz-tablet-oscilloscope/

They have developed an alternate firmware for the device so that would give you a big head start on the software.

 
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Offline ebastlerTopic starter

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Re: Component tester with I(U) diagram?
« Reply #23 on: October 03, 2024, 07:05:23 am »
Just as a cross-reference -- of course this topic has been discussed before on the forum: https://www.eevblog.com/forum/beginners/dirt-cheap-and-simple-scope-based-component-tester-curve-tracer/. References to various Octopus-style adapters for oscilloscope & function generator (or AC line voltage), and a very nice introduction to the fully integrated Huntron Tracker which I had not been aware of. (A dedicated I/U tracer with built-in little CRT.)

I have ordered a couple of 3.2" touch displays and started drafting a schematic and a PCB layout. This should make for a neat self-contained unit, the size of a pack of cigarettes (or playing cards, choose you preferred vice  ;)). I am planning for +- 12V maximum range, plus the ability to reduce the test voltage and zoom in on the current measurement in software, using the 12 bit ADC/DAC in an STM32. Does +- 1.5V as the smallest range seem reasonable for safe in-circuit testing?

Most importantly, I already have a name for it: The working title is "Duopus", an Octopus with only the two test leads left... I will open a new thread in the Projects section when I have something tangible.
 
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Offline kripton2035

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Re: Component tester with I(U) diagram?
« Reply #24 on: October 03, 2024, 09:12:45 am »
one suggestion: plan to add a third test lead, to compare two boards quickly, by having two traces in different colors.
like what does the huntron but with a crt display the two traces are the same color...
 
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