Author: Al Williams

4394 Articles

It’s Remotely Ham Radio

December 11, 2024 by 33 Comments

Have you ever considered running your ham radio remotely? It has been feasible for years but not always easy. Recently, I realized that most of the pieces you need to get on the air remotely are commonplace, so I decided to take the plunge. I won’t give step-by-step instructions because your radio, computer setup, and goals are probably different from mine. But I will give you a general outline of what you can do.

I’m fortunate enough to have a sizeable freestanding shop in my backyard. When I had it built, I thought it was huge. Now, not so much. The little space is crammed with test equipment, soldering gear, laser cutters, drill presses, and 3D printers. I’ve been a ham for decades, but I didn’t have room for the radios, nor did I have an antenna up. But a few months ago, I made space, set some radios up, strung out a piece of wire, and got back on the air. I had so much fun I decided it was time to buy a new radio. But I didn’t want to have to go out to the shop (or the lab, as I like to call it) just to relax with some radio time.

Continue reading “It’s Remotely Ham Radio” →

Cheap FPGA PCIe Development

December 7, 2024 by 18 Comments

Typically, if you want to build an FPGA project inside a PC, you’d need a fairly expensive development board that plugs into the bus. However, [CircuitValley] found some IBM RS-485 boards that are little more than a PCIe board with an Intel FPGA onboard. These are widely avaiable on the surplus market for around $20 shipped. He’s been documenting how to use them.

The FPGA onboard is a Cyclone IV with about 21,000 logic elements and a little over 750 kbits of memory. The board itself has configuration memory, power management, and a few connectors. The JTAG header is unpopulated, but the footprint is there. You simply need to supply a surface-mount pin header and an external JTAG probe, and you can program. Even if you aren’t interested in using an FPGA board, the reverse engineer steps are fun to watch.

The situation reminds us a little of the RTL-SDR — when a device uses a programmable device to perform nearly all of its functions, it is subject to your reprogramming. What would you do with a custom PCIe card? You tell us. Need a refresher on the bus? We can help. Thinking of building some sort of FPGA accelerator? Maybe try RIFFA.

Continue reading “Cheap FPGA PCIe Development” →

Microchess Remembered

December 7, 2024 by 10 Comments

Playing chess has always been a bellwether for computers. The game isn’t trivial, but the rules are managably simple. However, the game is too complex to be easily solved entirely, so you have to use tricky software to play a credible game. Big computers do have an advantage, of course. But Microchess — arguably the first commercial game for home computers — was able to play on tiny machines like the Kim-1. [Joachim Froholt] interviewed [Peter Jennings] — the man behind Microchess to learn the whole story of its creation.

In 1960, [Jennings] was ten years old and had to persuade the local librarian to let him read adult books on electronics and computers. Five years later, a ham radio teletype and some circuitry helped him practice chess openings and was the first of many chess-playing machines he’d build or program.

Microchess itself took six months of painstaking programming, entering hex codes into the computer. Word leaked out from a user’s group meeting (where Microchess beat a human player), and [Jennings] was swamped with requests for the program. In late 1976, the program was offered for sale as a teletype listing or, for an extra $3, a cassette tape.

The program went on to be very successful and moved to other platforms. Commodore even made a special dedicated device based on the Kim-1 to play Microchess, a piece of hardware unique enough that [Michael Gardi] honored it with one of his phenomenal replicas.

Antenna Measurement In Theory And Practice

December 6, 2024 by 9 Comments

If you want to analyze an antenna, you can use simulation software or you can build an antenna and make measurements. [All Electroncs Channel] does both and show you how you can do it, too, in the video below.

The antenna in question is a loop antenna. He uses a professional VNA (Vector Network Analyzer) but you could get away with a hobby-grade VNA, too. The software for simulation is 4NEC2.

The VNA shows the electrical characteristics of the antenna, which is one of the things you can pull from the simulation software. You can also get a lot of other information. You’d need to use a field strength meter or something similar to get some of the other information in the real world.

The antenna simulation software is a powerful engine and 4NEC2 gives you an easy way to use it with a GUI. You can see all the graphs and plots easily, too. Unfortunately, it is Windows software, but we hear it will run under Wine.

The practical measurement is a little different from the simulation, often because the simulation is perfect and the real antenna has non-ideal elements. [Grégory] points out that changing simulation parameters is a great way to develop intuition about — in this case — antennas.

Want to dive into antennas? We can help with that. Or, you can start with a simple explanation.

Continue reading “Antenna Measurement In Theory And Practice” →

VNAs And Crystals

December 6, 2024 by 7 Comments

Oscillators may use crystals as precise tuned circuits. If you have a vector network analyzer (VNA) — or even some basic test equipment — you can use it to learn the parameters of a crystal. [All Electronics Channel] has the details, and you can see how in the video below.

There was a time when a VNA was an exotic piece of gear, but these days they are relatively common. Crystal parameters are important because crystals have a series resonance and a parallel resonance and they are not at the same frequency. You also may need to know how much loading capacitance you have to supply to get the crystal at the right frequency.

Sometimes, you want to pull the crystal frequency, and the parameters will help you figure that out, too. It can also help if you have a crystal specified as series in a parallel-mode oscillator or vice versa.

If you don’t have a VNA, you can use a tracking signal generator, as [Grégory] shows towards the middle of the video. The quality of a tuned circuit depends on the Q factor, and crystals have a very high Q factor.

We did something similar in 2018. The other way to pull a crystal frequency is a bit extreme.

Continue reading “VNAs And Crystals” →

How Corroded Can A Motherboard Be?

December 5, 2024 by 9 Comments

We will admit it. If we found a 386 motherboard as badly corroded as the one [Bits und Bolts] did, we would trash it—not him, though. In fact, we were surprised when he showed it and said he had already removed most of it in vinegar. You can check the board out in the video below.

There was still a lot of work to do on both the front and back of the board. The motherboard was a Biostar and while it isn’t as dense as a modern board, it still had plenty of surface mount parts jammed in.

Continue reading “How Corroded Can A Motherboard Be?” →

A Brief History Of Teleportation

December 5, 2024 by 88 Comments

OK, I know. We don’t have practical teleportation. But that hasn’t stopped generations of science fiction authors and movie makers from building stories around it. If you ask most ordinary people, they’d tell you the idea originated with the Star Trek transporter, but that’s far from the truth. So when did people start thinking about teleporting?

Ground Rules

Maybe it isn’t fair, but I will draw the line at magic or unexplained teleportation. So “The Tempest”, for example, doesn’t use technology but magic. To get to Barsoom, John Carter wished or slept to teleport to Mars. So, while technology might seem like magic, we’re focusing on stories where some kind of machine can send something — usually people — to somewhere else.

Of course, there’s a fine line between pure magic and pure technology where they overlap. For example, in the opera “Der Ring des Nibelungen”, a magic helmet gives people powers, including that of teleportation. While you could argue that Tarnhelm — the name of the magic helmet — was a technological artifact, it is still explained by magic, not science.

Some systems need a transmitter and a receiver. Sometimes, you only need the transmitter. Sometimes, you can only teleport within a limited range, but other make-believe systems can transport an entire starship across the galaxy.

Early Teleporters

The Man without a Body is a story from 1877 in which a scientist is able to transmit a cat via a telegraph wire. Encouraged, he attempts the same feat with himself, but the battery dies in the middle, leaving him with a disembodied head. The ending is decidedly devoid of science, but the story is possibly the earliest one with a machine sending matter across a distance.

Continue reading “A Brief History Of Teleportation” →