Author: Al Williams

4490 Articles

A 1947 Radio Gets A Face Lift

May 6, 2026 by 6 Comments

We’ve all done it. We spy an old radio at a garage sale or resale shop. We know someone should bring it back to life, but it looks like a project, so we pass it by. Not [Ken] from [Ken’s Shop]. He found an Arvin 664A AM radio from 1947 in what appears to be a home-built cabinet and decided to bring it back to life.

From what we could find, the original case was a white plastic, not the wood box it is in today. So the first challenge was simply getting inside to see what was going on. Continue reading “A 1947 Radio Gets A Face Lift” →

Retrotechtacular: Julius Sumner Miller Breaks Lamps With Magnets

May 6, 2026 by 23 Comments

If you watched the Mickey Mouse Club way back when, you might remember Professor Wonderful, who was, in reality, physics professor [Julius Sumner Miller]. He also had his own show, “Why Is It So?” along with appearances on talk shows. We recently ran across one of the shows from 1962 where [Miller] uses electromagnets to break a lamp.

[Miller] moved to Australia, and this episode is from the Australian version of “Why Is It So?” As you might expect, given the topic, the professor covers Oersted and Faraday.

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Matching Transistors

May 2, 2026 by 14 Comments

Transistors in some circuit configurations work together and, frequently, need to be matched. This is so common that you can sometimes find ICs that are just a pair of transistors made with the same piece of silicon, so they should be matched very closely by default. But with discrete transistors, two devices of the same type are not always identical. [Learn Electronics Repair] covers the topic and explains how to match devices in the video below.

Depending on the circuit, the matching parameters may be different, but generally, the idea is that you want similar gains or matching saturation characteristics. The reason is that when you have multiple transistors working together, you don’t want one to do more work than the other device. This is inefficient and could drive the “better” component to fail.

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AT&T’s Unix PC — We Hardly Knew You

April 30, 2026 by 39 Comments

Before Linux, there was Unix. It was great, but it was and has been plagued by problems with licensing and proprietary competition. [Vintage Appartus] recalls, for example, the AT&T Unix PC from the 1980s. It was awesome, but you’ve probably never heard of it. For 1985, it was a nice setup. You got a 10 MHz Motorola 68010, 512K of RAM (but upgradable to 4M), a floppy, a modem, a 720×384 monochrome screen, and a 10 or 20 MB hard drive. You can check out the video explaining the machine and its problems below.

Physically, the computer looked like a high-end Apple ][ with a removable keyboard and a built-in monitor. Expansion was via three slots. Cold start took about three minutes, and then you have a fairly normal Unix setup for the period.

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Electronics Near Zero

April 30, 2026 by 5 Comments

Normally, when you design an electronic gadget, you worry about how hot it will get. Automotive-grade components, for example, often have higher allowable temperatures than commercial parts. However, extremely cold environments, such as deep space or the interiors of quantum computers, are also challenging. Researchers at King Abdullah University of Science and Technology believe gallium oxide may be key to operating near absolute zero.

According to [Vishal Khandelwal], one of the researchers, most conventional electronics fail below -173C or 100K. Quantum computers routinely operate at 4K. However, β-Ga2O3 is a wide-bandgap semiconductor that has low current leakage and works at high temperatures up to 500C. However, it also avoids the freeze-out effect that traps electrons in other semiconductor materials.

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Using A VT-100 Today

April 29, 2026 by 21 Comments

You may not know what a ADM-3, a TV910, or a H1420 are, but you probably have at least heard of a VT-100. They are all terminals from around the same time, but the DEC VT-100 is the terminal that practically everything today at least somewhat emulates. Even though a real VT-100 is rare, since it defined what have become ANSI escape sequences, most computers you’ve used in the last few decades speak some variation of the VT-100’s language. [Nikhil] wanted to see if you could use a VT-100 for real work today.

While the VT-100 wasn’t a general-purpose computer, it did have an 8080 inside. It only had about 3K of RAM, which was enough to act as a serial terminal. A USB serial port and a terminal with modern Linux, how hard could it be?

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Digital Signal Processing On The Pi Pico

April 29, 2026 by 10 Comments

If you want to dabble in audio digital signal processing, you would probably think of grabbing a dedicated DSP chip. But thanks to [WeebLabs], you could just pick up a Pi Pico and use this full-featured DSP library.

The system supports plug-and-play USB audio interface that enumerates on Windows, Linux, macOS, and iOS. It can handle 16- or 24-bit inputs at up to 96 kHz. You can output up to four channels of 24-bit S/PDIF or I2S, or switch to an RP2350 to get eight channels. This lets you drive a DAC easily. There is also a direct output for a subwoofer that doesn’t require a DAC.

Each channel has a pre-amp, and a matrix mixer allows routing with different gains and phases for each input. An equalizer allows ten bands per channel. There are also modules to do volume leveling, loudness compensation, and headphone cross-feed.

The library uses both cores of the CPU and manages up to ten preset configurations. The Pico does get an overclock and uses a fixed-point representation. The Pico 2 (RP2350) doesn’t need overclocking and uses single-precision floating point.

Overall, this looks like a great base for any sort of soundcard-like project. We’ve seen DSP stunts on the Pico before. This might also make a nice base for other audio projects.