This week Jonathan Bennett and David Ruggles chat with James Smith about Manyfold, the self-hosted 3D print digital asset manager that’s on the Fediverse! Does it do live renders? Does it slice? Listen to find out!
Continue reading “FLOSS Weekly Episode 806: Manyfold — The Dopamine Of Open Source”
If you want to deliver the maximum power to a load — say from a transmitter to an antenna — then both the source and the load need to have the same impedance. In much of the radio communication world, that impedance happens to be 50Ω. But in the real world, your antenna may not give you quite the match you hoped for. For that reason, many hams use antenna tuners. This is especially important for modern radios that tend to fold their power output back if the mismatch is too great to protect their circuitry from high voltage spikes. But a tuner has to be adjusted, and often, you have to put a signal out over the air to make the adjustments to match your antenna to your transmitter.
There are several common designs of antenna tuners, but they all rely on some set of adjustable capacitors and inductors. The operator keys the transmitter and adjusts the knobs looking for a dip in the SWR reading. Once you know the settings for a particular frequency, you can probably just dial it back in later, but if you change frequency by too much or your antenna changes, you may have to retune.
It is polite to turn down the power as much as possible, but to make the measurements, you have to send some signal out the antenna. Or do you?
Several methods have been used in the past to adjust antennas, ranging from grid dip meters to antenna analyzers. Of course, these instruments also send a signal to the antenna, but usually, they are tiny signals, unlike the main transmitter, which may have trouble going below a watt or even five watts.
However, a recent piece of gear can make this task almost trivial: the vector network analyzer (VNA). Ok, so the VNA isn’t really that new, but until recently, they were quite expensive and unusual. Now, you can pick one up for nearly nothing in the form of the NanoVNA.
The VNA is, of course, a little transmitter that typically has a wide range coupled with a power detector. The transmitter can sweep a band, and the device can determine how much power goes forward and backward into the device under test. That allows it to calculate the SWR easily, among other parameters.
These days, not only are oscilloscopes very common, but even a cheap instrument today would have been the envy of the world’s greatest labs not that long ago. But back in the day, the home experimenter basically had two choices: buy a surplus scope that a big company was getting rid of or build a Heathkit. [Radiotvphononut] bought an old Heathkit OL-1 scope at an estate sale and set about putting it back in service.
If you are used to a modern scope, you’ll be amazed at how simple a scope like this can be. A handful of tubes and a CRT is the bulk of it. Of course, the OL-1 is an analog scope with a 400 kHz bandwidth. It did, however, have two channels, which was a rarity at the time.
The OL-1 was sold for a few years up to 1956 and cost about $30 as a kit. There was a version with a larger screen (five whole inches) that cost an extra $40, so you can bet there were more OL-1s sold since $40 was a big ask in 1956. While they don’t seem like much today, you were probably the envy of the ham club in 1956 when you lugged this in for show and tell.
This is a long video, but it pays off at the end. Overall, this was a more capable scope than the $66 scope from 10 years earlier we looked at. Did you ever wonder how people visualized signals before the CRT? Funny, we did too.
Continue reading “Classic Heathkit OL-1 Scope Gets Some TLC”
The Domain Name System (DNS) is a major functional component of the modern Internet. We rely on it for just about everything! It’s responsible for translating human-friendly domain names into numerical IP addresses that get traffic where it needs to go. At the heart of the system are the top-level domains (TLDs)—these sit atop the whole domain name hierarchy.
You might think these TLDs are largely immutable—rock solid objects that seldom change. That’s mostly true, but the problem is that these TLDs are sometimes linked to real-world concepts that are changeable. Like the political status of various countries! Then, things get altogether more complex. The .io top level domain is the latest example of that.
Continue reading “Will .IO Domain Names Survive A Geopolitical Rearrangement?”
[Sebastian Lederer] has created Tridora: an unusual stack-based CPU core intended for FPGA deployment, co-developed with its own Pascal compiler. The 32-bit word machine is unusual in that it has not one but three stacks, 16-bit instruction words, and a limited ISA, more like those of the 8-bit world. No multiply or divide instructions will be found in this CPU.
The design consists of about 500 lines of Verilog targeting the Digilent Arty-A7 FPGA board, which is based around the Xilinx Artix-7 FPGA line. [Sebastian] plans to support the Nexys A7 board, which boasts a larger FPGA array but has less RAM onboard. The CPU clocks in at 83 MHz with four clock cycles per instruction, so over 20 MIPS, which is not so shabby for a homebrew design. Wrapped around that core are a few simple peripherals, such as the all-important UART, an SD card controller and a VGA display driver. On the software side, the Pascal implementation is created from scratch with quite a few restrictions, but it can compile itself, so that’s a milestone achieved. [Sebastian] also says there is a rudimentary operating system, but at the moment, it’s a little more than a loader that’s bundled with the program image.
The Tridora Gitlab project hosts the Verilog source, an emulator (written in Golang, not Pascal) and a suite of example applications. We see quite a few custom CPUs, often using older or less popular programming languages. Here’s an FPGA-based Forth machine to get you started. Implementing programming languages from scratch is also a surprisingly common hack. Check out this from-scratch compiler for the Pretty Laughable Programming language.
It’s likely that many Hackaday readers will have had their interest in electronics as a child honed by exposure to an electronics kit. The type of toy that featured a console covered in electronic components with spring terminals, and on which a variety of projects could be built by wiring up circuits. [Matthew North Music] has a couple of these, and he’s made a video investigating whether they can be used to make music.
The kits he’s found are a Radio Shack one from we’re guessing the 1970s, and a “Cambridge University Recording Studio” kit that looks to be 1990s-vintage. The former is all discrete components and passive, while the latter sports that digital audio record/playback chip that was the thing to have in a novelty item three decades ago. With them both he can create a variety of oscillator and filter circuits, though for the video he settles for a fairly simple tone whose pitch is controlled by an light-dependent resistor, and a metronome as a drum beat.
The result is a little avant garde, but certainly shows promise. The beauty of these kits is they can now be had for a song, and as grown-ups we don’t have to follow the rules set out in the book, so we can see there’s a lot of fun to be had. We look forward to some brave soul using them in a life performance at a hacker camp. Continue reading “75-In-One Music”
[DTSS_Smudge] correctly intuits that if you are interested in an old Heathkit signal generator, you probably already know how to solder. So, in a recent video, he focused on the components he decided to update for safety and other reasons. Meanwhile, we get treated to a nice teardown of this iconic piece of test gear.
If you didn’t grow up in the 1960s, it seems strange that the device has a polarized line cord with one end connected to the chassis. But that used to be quite common, just like kids didn’t wear helmets on bikes in those days.
A lot of TVs were “hot chassis” back then, too. We were always taught to touch the chassis with the back of your hand first. That way, if you get a shock, the associated muscle contraction will pull your hand away from the electricity. Touching it normally will make you grip the offending chassis hard, and you probably won’t be able to let go until someone kindly pulls the plug or a fuse blows.
These signal generators were very common back in the day. A lot of Heathkit gear was very serviceable and more affordable than the commercial alternatives. In 1970, these cost about $32 as a kit or $60 already built. While $32 doesn’t sound like much, it is equivalent to $260 today, so not an impulse buy.
Some of the parts are simply irreplaceable. The variable capacitor would be tough to source since it is a special type. The coils would also be tough to find replacements, although you might have luck rewinding them if it were necessary.
We are spoiled today with so many cheap quality instruments available. However, there was something satisfying about building your own gear and it certainly helped if you ever had to fix it.
There was so much Heathkit gear around that even though they’ve been gone for years, you still see quite a few units in use. Not all of their gear had tubes, but some of our favorite ones did.
