On an old fashioned bench a signal generator was once an indispensable instrument, but has now largely been supplanted by the more versatile function generator. Sometimes there’s a less demanding need for a clock signal though, and one way that might be served comes from [Rupin Chheda]’s square wave generator. It’s a small PCB designed to sit at the end of a breadboard and provide handy access to a range of clocks.
On the board is a crystal oscillator running at the usual digital clock frequency of 32.768 kHz, and a CMOS divider chain. This provides frequencies from 2048 Hz down to 0.5 Hz for good measure. It’s a simple but oh-so-useful board, and we can imagine more than a few of you finding space for it on your own benches.
When I was a student, I was a diehard Commodore Amiga user, having upgraded to an A500+ from my Sinclair Spectrum. The Amiga could do it all, it became my programming environment for electronic engineering course work, my audio workstation for student radio, my gaming hub, and much more.
One thing that was part of my course work it couldn’t do very well, which was be exactly like the PCs in my university’s lab. I feel old when I reflect that it’s 35 years ago, and remember sitting down in front of a Tulip PC-XT clone to compile my C code written on the Amiga. Eventually I cobbled together a 286 from cast-off parts, and entered the PC age. Alongside the Amiga it felt like a retrograde step, but mastering DOS 3.3 was arguably more useful to my career than AmigaDOS.
It’s DOS, But It’s Not MS-DOS
Where do I want to go today?
I don’t think I’ve used a pure DOS machine as anything but an occasional retrocomputing curio since some time in the late 1990s, because the Microsoft world long ago headed off into Windows country while I’ve been a Linux user for a very long time. But DOS hasn’t gone away even if Microsoft left it behind, because the FreeDOS project have created an entirely open-source replacement. It’s not MS-DOS, but it’s DOS. It does everything the way your old machine did, but in a lot of cases better and faster. Can I use it as one of my Daily Drivers here in the 2020s? There is only one way to find out.
With few exceptions, an important part of using an OS for this series is to run it on real hardware rather than an emulator. To that end I fished out my lowest-spec PC, a 2010 HP Mini 10 netbook that I hold onto for sentimental reasons. With a 1.6 GHz single core 32 bit Atom processor and a couple of gigabytes of memory it’s a very slow machine for modern desktop Linux, but given that FreeDOS can run on even the earliest PCs it’s a DOS powerhouse. To make it even more ridiculously overspecified I put a 2.5″ SSD in it, and downloaded the FreeDOS USB installer image. Continue reading “Jenny’s Daily Drivers: FreeDOS 1.4”→
Having a chiller is often essential for the chemistry laboratory, but what if you’re somewhere without easy access to water, nevermind a mains outlet to plug your usual chiller into? In that case you can build a portable one that will happily run off the 12 VDC provided by a mobile source like the accessory outlet in a car while reusing the water from its reservoir, as demonstrated by [Markus Bindhammer] in a recent video.
The build uses a compressor-based freezer as the base, which is significantly more capable than the typical Peltier-cooled refrigerators that cannot cool as fast or efficiently. The changes he made involve running in- and outlet tubing into the freezer’s compartment, with a submerged 12 VDC water pump providing the water to the outlet. This pump is controlled by a variable speed controller board that’s put in a box on the outside with the power lead also sneaking into the freezer. With these modifications in place the freezer’s functionality isn’t significantly impacted, so it can be used as normal.
After filling the compartment with water, the lid is closed and the freezer engaged. The pump controller is then switched on, with the water flow adjusted to fit the distillation job at hand. Although in this case a fairly small freezer was modified, nobody is saying that you cannot also do it with a much larger freezer, and fill it with ice cream and other treats to help it and lab critters cool down faster.
Australia is known for great beaches, top-tier coffee, and a laidback approach to life that really doesn’t square with all the rules and regulations that exist Down Under. What it isn’t known for is being a spacefaring nation.
As it stands, a startup called Gilmour Space has been making great efforts to give Australia the orbital launch capability it’s never had. After numerous hurdles and delays, the company finally got their rocket off the launch pad. Unfortunately, it just didn’t get much farther than that.
The printer itself is a key hardware portion of the hack, but the hack itself is purely organizational. [Laurie] started with post-its before adding automation. Before the post-it notes came a simple realization: [Laurie] could sit and play games for hours, but not buckle down for serious work for more than a few minutes, if he could even get started. (Who can’t relate?) That sent him down a rabbit hole reading about the psychology of what makes games so addictive — and the idea of “gamification” that was so popular in educational circles not long ago.
Unlike work, games give you a loop of unambiguous, instant, and continuous feedback to pump your dopamine circuits. [Laurie] uses the example of an FPS. You aim, you shoot — and either you miss, or you hit the target. Either way, there’s feedback. When you hit, your brain gives you dopamine. This fast loop of input -> feedback is what [Laurie] felt he was missing from his day.
Reloading filament on a 3D printer is hardly anyone’s favorite task, but it’s even worse when you’re trying to shove stiff filament down a long and winding Bowden tube. Enter the speed loader from [Mr Flippant], which aims to take the pain out of this mechanically-frustrating chore.
The design is simple enough. It’s a small handheld tool that uses a 12 VDC gear motor to drive a set of Bondtech-style drive gears that you might find in an extruder. They’re assembled in a 3D printed housing with a microswitch to activate the motor, and a 9 volt battery to supply the juice.
To use the device, first thread the filament into the beginning of the Bowden tube. The idler gear is on a hinge, such that clamping it into position around the filament with the main gear activates the microswitch and turns the motor on, driving the filament all the way to the extruder. Job done! [Mr Flippant] notes that the filament should be as straight and unkinked as possible for best results, but that’s good advice when 3D printing in general.
