Recent Posts

1

Metrology / Automated PCB reverse engineering idea

« Last post by Rjc987 on Today at 04:59:10 pm »

Hey guys,
One piece of test equipment I've never seen is an automated PCB reverse engineering solution - something that could take a PCB and either through imagery or direct measurement, output a general schematic of what connects to what. there's been times when I've been very busy and get in a piece of equipment that has a convoluted board which I don't have any schematics or information about and which something like that would be a huge timesaver and a massive help when reverse engineering or diagnosing.

So I was wondering why and thinking about ways it could be done - the first idea I had was using simple pcb imagery and machine learning but the fact that traces are hidden underneath ic's and inner layers, plus perspective and lighting means bigger components are going to be blocking things, and glossy black or white solder masks make it almost impossible to get a clear image of traces etc. I feel like that might not work very well.

So how about this- just a simple, very dense bed of nails style fixture completely filled top and bottom, Connected in some matrix array allowing a continuity signal to be applied sequentially from pin to pin and record every other pin which has continuity or a resistance value. This could then be processed into a boardview type file using images of the boards with each node selectable to display all related connections. It obviously won't work with bga's etc, and it would probably work best for low to medium density PCBs but am I missing anything here? It doesn't seem like it would be that difficult of a project to me, I imagine the hardest part would be the coding. Any thoughts? Suggestions?

2

Programming / Re: Linux Dependency Black Hole

« Last post by tatel on Today at 04:58:53 pm »

Well, I would say, if python >3.8 could be used, then the "vendor" is to blame for bad packaging.

I guess you are looking to use some specific software for your own reasons.

If that's not the case, then I would look at the hamradio task. You can click the names on the previously given link to see a description. Perhaps there's enough stuff there to make you jump over a couple steps. E.g, I see there's a fork, jtdx, with a high enough version number, of that WSJT-X thing that is driven metrologist nuts on that other thread. I think the stuff in that link it's worth a look. It could all be installed by just ticking the "hamradio" task during the install.

In my experience, it's better to stick with pure FOSS than to try and use some software coming from a for-profit source. Many times, it's not as easy and doesn't have all the features of privative software. FreeCAD comes to mind almost immediately. But in the long run I think that's often worth the hassle; it will not vanish when the vendor gets bought or goes out of business. Particularly if you aren't going to use it professionally. OTOH, GRASS GIS was the thing that got me into Linux: it was able to do much more than any privative GIS software we could afford then. YMMV.

3

Thermal Imaging / Re: The new Tooltop T7 with 'claimed' 256 x 192 sensor. Genuine 256 x 192?

« Last post by LooseJunkHater on Today at 04:55:56 pm »

Old thread but I ended up buying the Tooltop T7 and use it with the P2 Pro app. It's a really nice thermal camera for ~100USD. The pixels appear to be very closely matched. Previously I was using a Seek micro USB thermal camera and the pixels were really NOT matched, so the temperature differences between pixels was very noticeable. This has been a great upgrade for me personally.

4

Test Equipment / Re: Choosing between entry-level 12-bit DSOs

« Last post by gf on Today at 04:54:51 pm »

please note what you keep talking is a combination of sample rate and Sinc reconstruction. turn off Sinc and your point will become moot, granted signal can be a little weird when spectral content contains element more than half the sampling rate, using "Line" or vector plot. but not as severe when your turn on Sinc.

Umm... How would you describe, say, a 170 MHz sine signal sampled at 312 MSa/s, when shown in dot mode or with linear interpolation? It would look severely misleading in my book. Sinc interpolation is not the issue here.

170 MHz folds back to 142 MHz in the first Nyquist zone. So it looks like you had sampled a 142 MHz sine wave.

5

General Technical Chat / Re: Relocation problems trying to stay in Electronics work in UK

« Last post by nigelwright7557 on Today at 04:53:11 pm »

Having bad work colleagues can be a nightmare.

I was given some work to do so got on with it.
Half way through the job a delivery van arrived to pick them up.
The secretary had booked the van without asking me when they would be ready.
I was told off ! so I left the business.

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Test Equipment / Re: Multimeter selection for production testing

« Last post by bdunham7 on Today at 04:52:29 pm »

And to make sure people understood me correctly, problem is that if meter goes temporarily open circuit when switching between ranges. It should not but better check.
Although that can be worked around too with bypass relay that you enable relay, switch, disable relay, measure.

You would think it would be simple enough to design them so they don't, but I've seen quite a few meters that have an interruption in the current shunts when switching ranges, including the HP 34401A I just tested. It's typically a few milliseconds as relays change position--in the case of the 34401A it is a set of DPST contacts switching from one to the other.  In the OP's case, a simple bypass capacitor along with making sure to do the switching at the 100µA level should be good.

7

General Technical Chat / Re: A serious (as in not troll) requestfor help w/ultrasonic transducer

« Last post by watchmaker on Today at 04:52:08 pm »

Floobydust,

I know what you mean.  A couple years ago I had a call from a BAE Sr. Scientist with a broken detent in his marine chronometer.  Said his team was unable to come up with a plan to make one.  Two hundred years ago these were made by a couple families in Lancaster UK working by lamplight and to go/no no gauges.  I filed and polished them by hand in a swing tool.

But since it was "impossible" to program on CNC (toward the end I milled out the rough blanks on a Sherline), the "kids" were flummoxed.

I think growing up with smart phones has something to do with it.  When we were kids, if we got jammed up we had to figure it out (age appropriate trouble to get into and resolve).  Today kids do not practice problem solving skills beyond figuring out what search terms to use.

Over statement I agree.  But even medical schools are complaining.

Making mistakes while growing up is highly under valued!

8

Test Equipment / Re: Multimeter selection for production testing

« Last post by 2N3055 on Today at 04:51:40 pm »

I still recommend checking if SDM3045X switches between needed ranges seamlessly or is it "brake-before-make" when switching shunts.

Specifically with the SDM3045X there is also the issue of the 'ranges within ranges' where it switches internally at 2V even in the 6V range.  I wonder if that also happens at 2A in the 6A range--that might be problematic or at least super-annoying since this is right at the specfied test point.  Locking it in the 10A range (with less resolution) or getting an SDM3055 instead would be solutions to that issue,if I'm not imagining it.

I personally would recommend upgrade SDM3055 to better future proof it for not much more money.
But even locking SDM3045X in 10A range would be good enough for 1% needed.
But I agree I would go with SDM3055 and have no compromise option for less than 500€

9

Dodgy Technology / Re: Bad/bloated web design

« Last post by hneve on Today at 04:51:04 pm »

Oh, the autoplay sound and video. It's super annoying when you open a page, and suddenly, noise blasts out of nowhere! It's especially rough when you're browsing in a quiet place. And then there's the excessive fake loading spinners. They trick you into thinking something's happening when it wastes your time. Both disrupt the browsing experience and make you want to close the tab ASAP.

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Repair / Re: Nichicon Electrolytic Capacitors leaking - common problem? ( Rifa X and Y also)

« Last post by tggzzz on Today at 04:49:48 pm »

Im in the middle of recapping the P/S on an HP 8080A. Found all the rifas but still something wrong... test pins at the p/s are all reading correctly (A = 11.8v,  B = 5v ~ 1.8v saw, etc.) but nothing at the multicon. Hoping someone has a schematic or a link.

Don't know what you mean by "multicon".

Don't forget the ripple (AC) voltage is as important as the mean (DC) voltage, and is a better indicator of whether the bulk capacitors have dried out.