Component tester with I(U) diagram? - Page 1
Forum section: electronics / testgear

author: ebastler
author_rank: Super Contributor
timestamp: September 23, 2024, 05:43:59 am
content: 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.

author: tautech
author_rank: Super Contributor
timestamp: September 23, 2024, 06:42:45 am
content: Quote from: ebastler on September 23, 2024, 05:43:59 amMike 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/

author: ebastler
author_rank: Super Contributor
timestamp: September 23, 2024, 08:00:53 am
content: Quote from: tautech on September 23, 2024, 06:42:45 amThanks! 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.)

author: Aldo22
author_rank: Super Contributor
timestamp: September 23, 2024, 08:19:29 am
content: You mean something like this but "built-in"?https://youtu.be/kEuixDsiCW0?t=1413

author: ebastler
author_rank: Super Contributor
timestamp: September 23, 2024, 08:31:54 am
content: Quote from: Aldo22 on September 23, 2024, 08:19:29 amYes, 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.

author: Aldo22
author_rank: Super Contributor
timestamp: September 23, 2024, 08:41:17 am
content: Sounds like a very sensible and feasible DIY project, doesn't it?If you need a portable version, buy the DSO2512G from the video.

author: ebastler
author_rank: Super Contributor
timestamp: September 23, 2024, 08:50:42 am
content: Quote from: Aldo22 on September 23, 2024, 08:41:17 amYes, 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

author: Aldo22
author_rank: Super Contributor
timestamp: September 23, 2024, 09:03:18 am
content: Quote from: ebastler on September 23, 2024, 08:50:42 amBut that looks pretty much like what you're looking for. What's missing?

author: ebastler
author_rank: Super Contributor
timestamp: September 23, 2024, 09:14:50 am
content: Quote from: Aldo22 on September 23, 2024, 09:03:18 amYes, 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...

author: kripton2035
author_rank: Super Contributor
timestamp: September 23, 2024, 12:13:51 pm
content: 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?

author: voltsandjolts
author_rank: Unknown
timestamp: September 23, 2024, 12:25:29 pm
content: Cross-ref:https://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawg/msg5369042/#msg5369042https://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawg/msg5370329/#msg5370329

author: ebastler
author_rank: Super Contributor
timestamp: September 23, 2024, 03:03:40 pm
content: 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!

author: Evergreen64
author_rank: Newbie
timestamp: September 23, 2024, 10:52:52 pm
content: 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

author: kripton2035
author_rank: Super Contributor
timestamp: September 24, 2024, 06:12:07 am
content: 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...

author: ebastler
author_rank: Super Contributor
timestamp: September 24, 2024, 07:19:58 am
content: Quote from: kripton2035 on September 24, 2024, 06:12:07 amYes, 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?

author: ch_scr
author_rank: Frequent Contributor
timestamp: September 24, 2024, 08:28:11 am
content: What you describe sounds a lot like the "ELV Komponententester"

author: kripton2035
author_rank: Super Contributor
timestamp: September 24, 2024, 08:34:43 am
content: thishttps://www.aliexpress.com/item/1005006160645147.htmland a small supply - battery - adc board.and a big amount of software...

author: kripton2035
author_rank: Super Contributor
timestamp: September 24, 2024, 08:35:22 am
content: Quote from: ch_scr on September 24, 2024, 08:28:11 amyes, but this screen is too small

author: ebastler
author_rank: Super Contributor
timestamp: September 24, 2024, 08:50:12 am
content: Quote from: ch_scr on September 24, 2024, 08:28:11 amIt 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.

author: tautech
author_rank: Super Contributor
timestamp: September 24, 2024, 08:52:51 am
content: Quote from: ebastler on September 24, 2024, 07:19:58 amWhy ?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 ?

author: ebastler
author_rank: Super Contributor
timestamp: September 24, 2024, 08:55:36 am
content: Quote from: kripton2035 on September 24, 2024, 08:34:43 amYes, 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.

author: ebastler
author_rank: Super Contributor
timestamp: September 24, 2024, 08:57:54 am
content: Quote from: tautech on September 24, 2024, 08:52:51 amAs 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.

author: ledtester
author_rank: Super Contributor
timestamp: September 24, 2024, 10:01:39 am
content: 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.

author: ebastler
author_rank: Super Contributor
timestamp: October 03, 2024, 07:05:23 am
content: 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.

author: kripton2035
author_rank: Super Contributor
timestamp: October 03, 2024, 09:12:45 am
content: 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...

author: ebastler
author_rank: Super Contributor
timestamp: October 03, 2024, 10:04:21 am
content: Quote from: kripton2035 on October 03, 2024, 09:12:45 amIt's tempting to add more features! Should it also have a DC source output to set transistor base currents like the modern Huntron 2800? But space actually gets tight on the 3.2"-compatible circuit board, starting with the 4 mm jacks...For A/B comparison of components, wouldn't it actually be more convenient to capture them sequentially, using the same pair of test leads? Tap a button on the touch screen to say "I want to capture a reference", then the curve tracer waits until a stable I(U) curve is measured, stores and displays that in a different color. Then you move on to the next device(s) under test and measure as usual, with real-time display updates that allow comparison with the reference curve.Seems quicker to me, since you can still work with just two handheld test leads; no need to attach a third connection which would be difficult to juggle handheld. The old CRT-based Huntron trackers just did not have that option since they could not afford to build in a storage scope.Edit: "Triopus" would also work as a name, so at least that does not get in the way of a third connection.

author: kripton2035
author_rank: Super Contributor
timestamp: November 09, 2024, 11:08:08 am
content: looking around I found a device that may be what you're searching forI still find it quite expensive.https://www.alaonix.com/Ala_CT_2000.htmlthey have different screen sizes.

author: ebastler
author_rank: Super Contributor
timestamp: November 09, 2024, 11:35:02 am
content: Quote from: kripton2035 on November 09, 2024, 11:08:08 amYes, that comes closest to what I have in mind. We had a brief discussion about it early in this thread, replies #6 to #8.I have made some nice progress with my own design in the meantime: Using a 3.2" touch display module and a PCB of the same size sitting behind it. Kicad schematics and layout are actually complete, but I decided that I want to see the functionality in a hand-wired prototype before I commit to a small batch of populated PCBs at JLCPCB. Have had this on the back burner for a few weeks now since I got frustrated with STM32 programming, but it will definitely be continued!

author: watchmaker
author_rank: Unknown
timestamp: November 09, 2024, 01:06:38 pm
content: I know this is late, but here is my take on the issue. $30USD scope from Ali on top of a ThaiKit with a variable 15Vac tap off the PSU xformer to get 15 VAC for the octopus.A/B transistors on the ThaiKit, zeners and such on the octopus. Someone smarter can shrink the thing so the scope defines the footprint.