The Crystal (High Voltage) Method

June 13, 2023 by Al Williams 11 Comments

Do high voltages affect the resonant frequency of a crystal? Honestly, we never thought about it, but [Joe] did and decided to risk his analyzer to find out. He started with some decidedly old-school crystals like you might have found in a 1960-era Novice rig. Since the crystal is piezoelectric, he wondered if using a high DC voltage to bend the crystal to move the frequency to create a variable crystal oscillator (sometimes called a VXO).

He created a rig to block DC away from the network analyzer and then feed voltage directly across the crystal. The voltage was from an ESD tester that provides over 1000 volts.

Getting a crystal to change much in frequency is difficult, which is why they are useful. So we weren’t surprised that even at very high voltages, the effect wasn’t very large. It did change the frequency, but it just wasn’t very much.

At one point, it looked like he might have killed the test equipment. There was a time when letting the smoke out of a network analyzer would have been a costly mistake, but these days the cost isn’t that prohibitive. In the end, this experiment probably doesn’t produce any practical results. Still, it is interesting, and we always enjoy watching anything that gives us more intuition about the behavior of circuits or, in this case, circuit elements.

If you need a refresher on crystal oscillators, we can help. There are other ways to modify a crystal’s frequency, of course.

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Spy Tech: Unshredding Documents

June 12, 2023 by Al Williams 38 Comments

Bureaucracies generate paper, usually lots of paper. Anything you consider private — especially anything that could get you in trouble — should go in a “burn box” which is usually a locked trash can that is periodically emptied into an incinerator. However, what about a paper shredder? Who hasn’t seen a movie or TV show where the office furiously shreds papers as the FBI, SEC, or some other three-letter-agency is trying to crash the door down?

That might have been the scene in the late 1980s when Germany reunified. The East German Ministry of State Security — known as the Stasi — had records of unlawful activity and, probably, information about people of interest. The staff made a best effort to destroy these records, but they did not quite complete their task.

The collapsing East German government ordered documents destroyed, and many were pulped or burned. However, many of the documents were shredded by hand, stuffed into bags, and were awaiting final destruction. There were also some documents destroyed by the interim government in 1990. Today there are about 16,000 of these bags remaining, each with 2,500 to 3,000 pieces of pages in them.

Machine-shredded documents were too small to recover, but the hand-shredded documents should be possible to reconstruct. After all, they do it all the time in spy movies, right? With modern computers and vision systems, it should be a snap.

You’d think so, anyway.

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Modern Brownie Camera Talks SD And WiFi

June 11, 2023 by Al Williams 4 Comments

If you’re at all into nostalgic cameras, you’ve certainly seen the old Brownie from Kodak. They were everywhere, and feature an iconic look. [JGJMatt] couldn’t help but notice that you could easily find old ones at a good price, but finding and developing No. 117 film these days can be challenging. But thanks to a little 3D printing, you can install an ESP32 camera inside and wind up with a modern but retro-stylish camera. The new old camera will work with a memory card or send data over WiFi.

The Brownie dates back to 1900 and cost, initially, one dollar. Of course, a dollar back then is worth about $35 now, but still not astronomical. After cleaning up and tuning up an old specimen, it was time to fire up the 3D printer.

There are also mods to the camera to let it accept an M12 lens. There are many lenses of that size you can choose from. There are a few other gotchas, like extending the camera cable, but it looks like you could readily reproduce this project if you wanted one of your very own.

We’ve seen old cameras converted before. Or, you can just start from scratch.

What Do You Want In A Programming Assistant?

June 10, 2023 by Al Williams 57 Comments

The Propellerheads released a song in 1998 entitled “History Repeating.” If you don’t know it, the lyrics include: “They say the next big thing is here. That the revolution’s near. But to me, it seems quite clear. That it’s all just a little bit of history repeating.” The next big thing today seems to be the AI chatbots. We’ve heard every opinion from the “revolutionize everything” to “destroy everything” camp. But, really, isn’t it a bit of history repeating itself? We get new tech. Some oversell it. Some fear it. Then, in the end, it becomes part of the ordinary landscape and seems unremarkable in the light of the new next big thing. Dynamite, the steam engine, cars, TV, and the Internet were all predicted to “ruin everything” at some point in the past.

History really does repeat itself. After all, when X-rays were discovered, they were claimed to cure pneumonia and other infections, along with other miracle cures. Those didn’t pan out, but we still use them for things they are good at. Calculators were going to ruin math classes. There are plenty of other examples.

This came to mind because a recent post from ACM has the contrary view that chatbots aren’t able to help real programmers. We’ve also seen that — maybe — it can, in limited ways. We suspect it is like getting a new larger monitor. At first, it seems huge. But in a week, it is just the normal monitor, and your old one — which had been perfectly adequate — seems tiny.

But we think there’s a larger point here. Maybe the chatbots will help programmers. Maybe they won’t. But clearly, programmers want some kind of help. We just aren’t sure what kind of help it is. Do we really want CoPilot to write our code for us? Do we want to ask Bard or ChatGPT/Bing what is the best way to balance a B-tree? Asking AI to do static code analysis seems to work pretty well.

So maybe your path to fame and maybe even riches is to figure out — AI-based or not — what people actually want in an automated programming assistant and build that. The home computer idea languished until someone figured out what people wanted to do with them. Video cassette didn’t make it into the home until companies figured out what people wanted most to watch on them.

How much and what kind of help do you want when you program? Or design a circuit or PCB? Or even a 3D model? Maybe AI isn’t going to take your job; it will just make it easier. We doubt, though, that it can much improve on Dame Shirley Bassey’s history lesson.

The PDP8 That Never Was: Hollow State Logic

June 9, 2023 by Al Williams 31 Comments

[Outer World Apps] noted that there was no PDP-8/V made by DEC — a variant that used vacuum tubes. So he’s decided to make one using about 320 6J6A tubes. He’s got a plan and a few boards completed — we can’t wait to see it finished.

The logic is actually done by crystal rectifiers, but the tubes do inversion. To make an and/or/invert gate requires a single triode or half of a 6J6A. A D flip flop requires three tubes or two tubes for a latch. In addition to the “crystal diodes,” the memory and I/O are a Raspberry Pi, and there are transistors to do level conversion between the tube logic and the Pi.

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Gesture Sensor Teardown Reveals Intel Heritage

June 9, 2023 by Al Williams 5 Comments

A few years ago, there was a rush of products on the market to detect motion. The idea being you could interact with your computer like they do on science fiction movies, with giant expressive hand motions in the air. Most of these were aimed at desktop computer users but one company, YouSpace, wanted to bring this technology to retail stores. [IMSAI Guy] got one of their sensor devices and decided to see what was inside it. You can see, too, in the video below.

The device appeared to have a laser inside, which motivated the teardown. We aren’t sure exactly what YouSpace had planned, but you can see their now-defunct website on the Wayback machine. The use cases listed didn’t really help us get a clear picture, so maybe that was part of the problem.

Getting into the device was the first challenge. Like many modern smartphones, there didn’t appear to be any fasteners, so you simply had to pry the case apart. Inside the case: a tiny circuit board and a metal assembly containing the laser and cameras that were easy to remove. The main PCB appears to be an Intel off-the-shelf board that was in many Intel RealSense products, and currently go for about $50 on eBay. The camera assembly looks a bit like an Intel D430, so it is possible the entire thing was off-the-shelf hardware. Even the little connector board is, technically, a D400 Interposer.

The peek into the structured light project under the microscope was interesting. We expected it would look different, and [IMSAI Guy] clearly didn’t expect its appearance either. The chip was made to beam a known pattern that the cameras would use to deduce the shape of the surfaces it hits.

If you can find these on the surplus market, they would probably be a good deal if you need this hardware which is typically pretty expensive. Just beware, though. Intel announced in late 2021 they were “winding down” RealSense. We don’t know if there will be third-party support in the future or if the whole product line will just be orphaned.

We’ve seen the occasional project that uses structured light. The technique can be very precise.

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Contrary View: Chatbots Don’t Help Programmers

June 8, 2023 by Al Williams 67 Comments

[Bertrand Meyer] is a decided contrarian in his views on AI and programming. In a recent Communications of the ACM blog post, he reveals that — unlike many others — he thinks AI in its current state isn’t very useful for practical programming. He was responding, in part, to another article from the ACM entitled “The End of Programming,” which, like many other articles, is claiming that, soon, no one will write software the way we do and have done for the last few decades. You can see [Matt Welsh] describe his thoughts on this in the video below. But [Bertrand] disagrees.

As we have also noted, [Bretrand] says:

“AI in its modern form, however, does not generate correct programs: it generates programs inferred from many earlier programs it has seen. These programs look correct but have no guarantee of correctness.”

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