Новини світу мікро- та наноелектроніки

Weekly discussion, complaint, and rant thread

Reddit:Electronics - Сбт, 03/07/2026 - 18:00

Open to anything, including discussions, complaints, and rants.

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My first two PCBs created while I try to teach myself electronics!

Reddit:Electronics - Сбт, 03/07/2026 - 08:41
My first two PCBs created while I try to teach myself electronics!

The first started as a way to test ADCs and parallel I/O, and I turned it into a toy oscilloscope using some software I wrote for my Raspberry Pi. I didn't really understand op-amp input bias current and so it doesn't really work properly with the probe in 10x mode. The offset is huge, but I now understand the mistake. I also used one more op-amp than I really needed, and could've gotten away with cheaper ones, but it works up to 50MS/s!

The second board is a buffered variable-gain amplifier test with voltage-variable gain and bias. I fell down a rabbit hole w/oscilloscopes and am working on making an improved 2-channel one with modern components, so I broke out some of the front end into a test board and just finished building it. It's a miracle the QFN op-amp works, I was sure I'd bridge something underneath it.

There's a subtle crucial mistake in the second design, all you need to know to spot it is that the second amp is an LMH6505. It somehow does partially function still!

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Risk assessment in the workplace

EDN Network - Птн, 03/06/2026 - 15:00

Risks come in more than one form. There are risks that arise from science and technology, and there are risks that arise from human motivations, which are not always of an obvious sort. This is about the latter.

I had a client company that was owned by a husband and wife for whom I had once solved a power supply thermal runaway problem. I had measured temperature rise versus time and temperature fall versus time, and of course, the two were not exactly the same. Their difference was quite pronounced when I first looked at the issue, but they were almost identical to each other after I had solved their problem. If you’re curious about that, please see the How2Power article here

A couple of years went by, and I got a call from that same company about a different power supply that also seemed to have a thermal runaway problem. By then, sadly, the husband had passed away, and only the wife remained to run the business.

During the first time frame, the wife had displayed a hair-trigger temper. Any moment of uncertainty as events unfolded would result in a raging torrent from her, to which her husband would make great efforts to calm her down. I would hear lines like “It’s okay. It’s oh-kay! Please relax. Things are going well.” to which she would then go silent, but now she didn’t have anyone to give her any assurance when it was needed.

An employee who had been promoted to Chief Engineer was my new point of contact. I explained to him that I would examine the thermal rise and thermal fall traits of this new power supply to see if indeed the same situation pertained as it did in the first case or not.

“There’s no need for that. I’ve already made those measurements.” He handed me a sheet of paper with columns of numbers, purportedly the data I had planned to acquire. That night, I examined those numbers and discovered that if you plotted the thermal rise and inverted a plot of the thermal fall, the two curves precisely lined up and were EXACTLY the same!! There was absolutely zero difference. They were totally spot on, no ifs, ands, buts, hows, whys, or wherefores, exactly the same, which meant that the rising and falling curves given to me were not the results of actual testing. They were false.

Confronted with a Chief Engineer whom I then knew to be dishonest and confronted with the woman whom I knew to be extremely volatile and prone to bursts of rage, I assessed the risk of dealing with it all to be unacceptable.

I made up some excuse (I don’t remember what it was) and declined to offer my services.

John Dunn is an electronics consultant and a graduate of The Polytechnic Institute of Brooklyn (BSEE) and of New York University (MSEE).

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