A photo of the MMD-1 on the workbench.

Restoring The E&L MMD-1 Mini-Micro Designer Single-Board Computer From 1977

October 29, 2025 by 12 Comments

Over on YouTube [CuriousMarc] and [TubeTimeUS] team up for a multi-part series E&L MMD-1 Mini-Micro Designer Restoration.

The E&L MMD-1 is a microcomputer trainer and breadboard for the Intel 8080. It’s the first ever single-board computer. What’s more, they mention in the video that E&L actually invented the breadboard with the middle trench for the ICs which is so familiar to us today; their US patent 228,136 was issued in August 1973.

The MMD-1 trainer has support circuits providing control logic, clock, bus drivers, voltage regulator, memory decoder, memory, I/O decoder, keyboard encoder, three 8-bit ports, an octal keyboard, and other support interconnects. They discuss in the video the Intel 1702 which is widely accepted as the first commercially available EPROM, dating back to 1971.

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Expert Systems: The Dawn Of AI

October 29, 2025 by 18 Comments

We’ll be honest. If you had told us a few decades ago we’d teach computers to do what we want, it would work some of the time, and you wouldn’t really be able to explain or predict exactly what it was going to do, we’d have thought you were crazy. Why not just get a person? But the dream of AI goes back to the earliest days of computers or even further, if you count Samuel Butler’s letter from 1863 musing on machines evolving into life, a theme he would revisit in the 1872 book Erewhon.

Of course, early real-life AI was nothing like you wanted. Eliza seemed pretty conversational, but you could quickly confuse the program. Hexapawn learned how to play an extremely simplified version of chess, but you could just as easily teach it to lose.

But the real AI work that looked promising was the field of expert systems. Unlike our current AI friends, expert systems were highly predictable. Of course, like any computer program, they could be wrong, but if they were, you could figure out why.

Experts?

As the name implies, expert systems drew from human experts. In theory, a specialized person known as a “knowledge engineer” would work with a human expert to distill his or her knowledge down to an essential form that the computer could handle.

This could range from the simple to the fiendishly complex, and if you think it was hard to do well, you aren’t wrong. Before getting into details, an example will help you follow how it works.

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Recreating A Homebrew Game System From 1987

October 29, 2025 by 10 Comments

We often take for granted how easy it is to get information in today’s modern, Internet-connected world. Especially around electronics projects, datasheets are generally a few clicks away, as are instructions for building almost anything. Not so in the late 80s where ordering physical catalogs of chips and their datasheets was generally required.

Mastering this landscape took a different skillset and far more determination than today, which is what makes the fact that a Japanese electronics hobbyist built a complete homebrew video game system from scratch in 1987 all the more impressive.[Alex] recently discovered this project and produced a replica of it with a few modern touches.

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All Hail The OC71

October 29, 2025 by 50 Comments

Such are the breadth of functions delivered by integrated circuits, it’s now rare to see a simple small-signal transistor project on these pages. But if you delve back into the roots of solid state electronics you’ll find a host of clever ways to get the most from the most basic of active parts.\

Everyone was familiar with their part numbers and characteristics, and if you were an electronics enthusiast in Europe it’s likely there was one part above all others that made its way onto your bench. [ElectronicsNotes] takes a look at the OC71, probably the most common PNP germanium transistor on the side of the Atlantic this is being written on.

When this device was launched in 1953 the transistor itself had only been invented a few years earlier, so while its relatively modest specs look pedestrian by today’s standards they represented a leap ahead in performance at the time. He touches on the thermal runaway which could affect germanium devices, and talks about the use of black silicone filling to reduce light sensitivity.

The OC71 was old hat by the 1970s, but electronics books of the era hadn’t caught up. Thus many engineers born long after the device’s heyday retain a soft spot for it. We recently even featured a teardown of a dead one.

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The winning entry, a photo of a fly on a grain of rice.

Nikon Small World Competition Announces 2025 Winners

October 28, 2025 by 3 Comments

They say that, sometimes, less is more. That would certainly apply to photomicrography, where you want to take pictures of tiny things. Nikon agrees, and they sponsor the Small World contest every year. The 2025 winners are a big — or not so big, maybe — deal.

This photomicrography competition dates back to 1975, so this is the 51st set of winners. First place went to [Zhang You] for his photograph of a rice weevil (sitophilus oryzae) on a grain of rice.

[You] is an entomologist from the Entomological Society of China. He says, “It pays to dive deep into entomology: understanding insects’ behaviors and mastering lighting, a standout work blends artistry with scientific rigor, capturing the very essence, energy, and spirit of these creatures.” We can’t argue with the results.

If you’re interested in Nikon and photography, you might also be interested in repairing a broken lens or a Nikon D3.

Web Development In… Pascal?

October 28, 2025 by 28 Comments

If you were asked to make an e-commerce website in 2025, what language would you reach for? Show of hands: JavaScript? Go? Pascal? Well, there was at least one taker for that last one: [jns], and he has an hour-long tutorial video showing you how he made it happen. 

The site in question is the web store for his personal business, Photronic Arts, so you cannot say [jns] does not have skin in the game. From the front end, this is HTML and could be anything upto and including Shopify under the hood. It’s not, though: it’s a wholly custom backend [jns] put together in FreePascal, using the Lazarus IDE.

There’s a case to be made for Pascal in the modern day, but when we wrote that we weren’t expecting to get tips about web development.  Ironically enough [jns] spends so much time giving the technical details in this video he doesn’t delve that deeply into why he chose FreePascal, especially when it’s clear he’s very familiar with C and C++. In his associated writeup on his Gopher page (link though Floodgap) [jns] simply declares it’s a language he’s quite fond of, which is reason enough of us. The source code is available, though on request, to avoid AI scraping. It’s a sad but understandable response to these modern times.

If you’re not into web development and want to see a deep-dive into how the backend works, this video is worth watching even if you don’t particularly care for Pascal. It’s also worth watching if you do know backend development, and are Pascal-curious. If neither of those things interest you, what about this Pascal Library for Arduino?

Thanks to [jns] for the tip! If you’re doing modern work with questionably-modern tools, we call that a hack and would love to hear from you.

 

Testing Cheap DC Breakers And How To Not Start Fires

October 28, 2025 by 11 Comments

One characteristic of adding PV solar to homes is a massive increase in high-voltage and high-current DC installations. With this comes a need for suitable breakers, but without the requisite knowledge it can be easy to set up a fire hazard. There is also the issue of online shopping platforms making it easy to get fuses and breakers that may not be quite as capable as they claim, never mind being rated for DC use.

Recently [Will Prowse] had a poke at a range of common purportedly DC-rated breakers from everyone’s favorite US-based seller of tat, to see whether they should be bought or avoided at all cost. Perhaps unsurprisingly the cheap breakers are about as dodgy as you’d imagine. With a hundred plus amps flowing through them they get surprisingly crispy, even if they generally did their job. Minus the few that arrived in a broken condition, of course.

Ultimately [Will] found that the molded case circuit break (MCCB) by one ‘DIHOOL’ performed the best. Compared to the competition, it is much larger and has sizeable terminals that avoid the quaint heat-soaking issues seen with the cheap-and-cheerful rest. At a mere $34 for the 125A-rated version, it’s still a fraction of the cost of a comparable Eaton MCCB, but should upset your insurance company significantly less than the alternatives.

Don’t forget to add in fuses, with [Will] testing a range of cheapo 12V DC fuses, to see which one will prevent fires, and which one cause them. Unsurprisingly, some of them like the Bojack-branded ones ran very hot, making them more of a liability than an asset.

As for what makes DC breakers so different from AC one is that the extinguishing point of a DC arc is much steeper, which means that an AC breaker is likely to fail to extinguish the arc when used for DC applications. This is why a properly rated and ideally certified breaker is essential, and also not really the point where you want to start saving money.

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