If you spend much time helping people with word processor programs, you’ll find that many people don’t really use much of the product. They type, change fonts, save, and print. But cross-references? Indexing? Largely, those parts of the program go unused. I’ve noticed the same thing with Git. We all use it constantly. But do we? You clone a repo. Work on it. Maybe switch branches and create a pull request. That’s about 80% of what you want to do under normal circumstances. But what if you want to do something out of the ordinary? Git is very flexible, but you do have to know the magic incantations.
For example, suppose you mess up a commit message — we never do that, of course, but just pretend. Or you accidentally added a file you didn’t want in the commit. Git has some very useful ways to deal with situations like this, especially the interactive rebase.
[ProjectsInFlight] has been doing some fantastic work documenting his DIY semiconductor fab lately. Next up: exploring down-and-dirty photolithography methods.
If you’ve been following along with this series — and why wouldn’t you? — you’ll recall [ProjectsInFlight]’s earlier experiments, like creating oxide layers on silicon chips with a homebrew tube furnace and exploring etchants that can selectively remove them. But just blasting away the oxide layer indiscriminately isn’t really something you need to do when etching the fine features needed to fabricate a working circuit. The trouble is, most of the common photoresist solutions used by commercial fabs are unobtainium for hobbyists, leading to a search for a suitable substitute.
Surprisingly, PCB photoresist film seemed to work quite well, but not without a lot of optimization by [ProjectsInFlight] to stick it to the silicon using a regular laminator. Also in need of a lot of tweaking was the use of a laser printer to create masks for the photolithography process on ordinary transparency film, including the surprisingly effective method of improving the opacity of prints with acetone vapor. There were also extensive experiments to determine the best exposure conditions, a workable development process, and the right etchants to use. Watch the video below for a deep dive into all those topics as well as the results, which are pretty good.
There’s a lot to be said for the methodical approach that [ProjectsInFlight] is taking here. Every process is explored exhaustively, with a variety of conditions tested before settling on what works best. It’s also nice to see that pretty much all of this has been accomplished with the most basic of materials, all of which are easily sourced and pretty cheap to boot. We’re looking forward to more of the same here, as well as to see what others do with this valuable groundwork.
Hydrofoils have fascinated naval architects and marine designers for years. Fitted with underwater wings, these designs traverse the waters at great speed with a minimum of drag. As with many innovative technologies, though, the use of hydrofoils is riddled with challenges that often offset the vast benefits they offer.
While hydrofoils promise a better marine transportation experience, their adoption hasn’t been smooth sailing. In this article, we’ll dive deep into the potential and pitfalls of hydrofoil designs, and look at the unique niches this technology serves today.
The Philips SAA1099 is perhaps one of the lesser-known among the crop of 1980s-era 8-bit sound generator chips, but with three stereo voices onboard it makes a capable instrument for chiptune experimentation. It’s attracted the attention of [Folkert van Heusden], who’s tried the novel experiment of seeing what happens when a sound chip’s clock is varied.
A quick search of the internet reveals that the chip, which appeared in early Sound Blaster cards, is intended to have an 8 MHz clock. He’s hooked it up to an Arduino as a variable clock source, which surprised us but it seems an ATmega328’s timer is faster than we expected.
There are a couple of WAV files, and as expected the clock frequency has a significant effect on the pitch. The samples just sweep up and down without much attempt at making a sound you’d want to hear, but it does raise an interesting possibility of adding a further pitch bending ability to the capabilities already in the chip. When these circuits were new we couldn’t control a clock on a whim with the 8-bit processors of the day, so of course none of us thought to try this at the time. He’s tried it, so you don’t have to.
Ever since an impromptu build completed during a two-week COVID-19 quarantine back in 2020, [Will Whang] has been steadily improving his Raspberry Pi solar photography setup. It integrates a lot of cool stuff: multiple sensors, high bandwidth storage, and some serious hardware. This is no junk drawer build either, the current version uses a $2000 USD solar telescope (an LS60M with 200mm lens) and a commercial AZ-GTi mount.
He also moved up somewhat with the imaging devices from the Raspberry Pi camera module he started with to two imaging sensors of his own: the OneInchEye and the StarlightEye, both fully open source. These two sensors feed data into the Raspberry Pi 4 Compute Module, which dumps the raw images into storage.
Because solar imaging is all about capturing a larger number of images, and then processing and picking the sharpest ones, you need speed. Far more than writing to an SD Card. So, the solution [Will] came up with was to build a rather complex system that uses a CF Express to NVME adapter that can keep up, but can be quickly swapped out.
Unfortunately, all of this hard work proved to be in vain when the eclipse came, and it was cloudy in [Wills] area. But there is always another interesting solar event around the corner, and it isn’t going anywhere for a few million years. [Will] is already looking at how to upgrade the system again with the new possibilities the Raspberry Pi 5 offers.
Back in presumably the early 1960s, [David]’s grandfather bought a console stereo featuring a record player, AM/FM radio and a rather astounding stereo speaker system that would be more than enough to cover a small concert hall. Having inherited this piece of auditory art after his grandfather’s passing, [David] has given the console stereo a prominent place in his living room, which is where we start the tour in a new video on the [Usagi Electric] YouTube channel.
Plentiful I/O on this 1960s vintage piece of Magnavox audio equipment.
Being a 1950s-vintage design that got produced into the 1960s in a variety of models, the Magnavox Concert Grand is an all-tube affair, with the only presence of semiconductors being the three transistors found in the ‘Phantom’ remote control. [David] unfortunately does not posses this remote control, although the receiver module is present in the unit. It appears to be similar to the 1960 1ST800F in possession by [electra225] over at the Classic HiFi Care forum, which can provide 50 Watt per channel, yet as noted in the forum post, the 44 tubes alone draw about 250 Watt, with [electra225] recording 377 Watt total with everything cranked up. Clearly a high power bill was a price one had to pay for having high-end audio back in that era.
After [David] takes his unit apart – made very easy due to the modular construction – he goes through the basic circuitry of the power supply, the amplifiers and even has a peek at the circuitry of the remote control which appears to use basic frequency modulation to transfer the intended action to the receiver. All of this is made quite easy as full schematics are available for the entire system, as was standard back in those days. Interesting is also the I/O module, which features an MPX section, for demodulating stereo FM which wasn’t standardized yet at the time. Finally, tape drive connectors are available, which would have been likely a reel-to-reel unit for maximum HiFi enjoyment.
With the only broken thing in [David]’s unit being the snapped wire on the tuner of the radio module (ironically caused by the disassembly), all that was changed before reassembly was a good clean, after which the console stereo was put back and tested. Reflecting an era when HiFi equipment was supposed to blend in with other furniture, it will likely continue to do service for [David] as the world’s fanciest TV soundbar for the foreseeable future.
The Vintage Computer Festival is coming to sunny Southern California in February 2024. That’s right, bring your Commodores, your Tandys, your PDP-11s, and Altairs. The world of retrocomputing will be open to vendors, visitors, and exhibitors at The Hotel Fera Events Center in Orange, California on February 17th and 18th, 2024.
If you’re thinking there already is a VCF out west, you’d be right. VCF West was held in August at the Computer History Museum. The CHM is in Mountain View, California. That puts it nearly at the epicenter of the microcomputer revolution of the ’70s and ’80s.
Southern California still had plenty of computer enthusiasts though. For the non-geographically inclined amongst us, SoCal is nearly 6 hours from Mountain View by car. We’re sure we’ll see many familiar faces at SoCal, along with plenty of new ones.
The Vintage Computer Federation holds several events across the country each year. You might have heard some music from VCF Midwest 2023 back in September. Hackaday was also out in force at VCF East this year, where our own [Bil Herd] moderated a panel of vintage computer YouTubers including [Usagi Electric], [Adrian’s Digital Basement], and [FranLab].
