Grid Leak Radio Draws The Waves

May 23, 2024 by Al Williams 11 Comments

[Stephen McNamera] found a schematic for a grid leak radio online and decided to throw together a few tubes on a piece of wood and see how it worked. As you can see in the video below, it works well. The video is a bit light on details, but the web page he found the plans on also has quite a bit of explanation.

The name “grid leak detector” is due to the grid leak resistor between the grid and ground, in this case, a 2.7 megaohm resistor. The first tube does everything, including AM detection. The second tube is just an audio amplifier that drives the speaker. This demodulation method relies on the cathode to control grid conduction characteristics and was found in radios up to about the 1930s. The control grid performs the usual function but also acts as a diode with the cathode, providing demodulation. In a way, this is similar to a crystal radio but with an amplified tube diode instead of a crystal.

It looks like [Stephen] wound his own coil, and the variable capacitor looks suspiciously like it may have come from an old AM radio. The of the old screw terminal tube sockets on the wood board looks great. Breadboard indeed! What we didn’t see is where the 150 V plate voltage comes from. You hope there is a transformer somewhere and some filter capacitors. Or, perhaps he has a high-voltage supply on the bench.

While tubes are technologically passe, we still like them. Especially in old radios. Just take care around the high voltages, please.

Continue reading “Grid Leak Radio Draws The Waves” →

Amber Compiles To Bash

May 22, 2024 by Al Williams 17 Comments

It certainly isn’t a new idea to compile a language into an intermediate language. The original C++ compiler outputs C code, for example. Enhanced versions of Fortran were often just conversions of new syntax to old syntax. Of course, it makes sense to output to some language that can run on lots of different platforms. So, using that logic, Amber makes perfect sense. It targets — no kidding — bash. You write with nice modern syntax and compile-time checks. The output is a bash script. Admittedly, sometimes a hard-to-read bash script, but still.

If you want to see the source code, it is available on GitHub. Since Windows doesn’t really support bash — if you don’t count things like Cygwin and WSL — Amber only officially supports Linux and MacOS. In addition to compiling files, Amber can also execute scripts directly which can be useful for a quick one-liner. If you use Visual Studio Code, you can find a syntax highlighter extension for Amber.

Continue reading “Amber Compiles To Bash” →

Hands On: AD409-Max Microscope

May 22, 2024 by Al Williams 18 Comments

It used to be that only the most well-equipped home electronics lab had a microscope. However, with SMD parts getting smaller and smaller, some kind of microscope is almost a necessity.

Luckily, you can get USB microscopes for a song now. If you’re willing to spend a little more, you can get even get microscopes that have little LCD screens. However, there are some problems with the cheaper end of these microscopes.

Many of them have small and wobbly stands that aren’t very practical. Some don’t leave you much room to get a soldering iron in between the lens and the part. Worse still, many cheap microscopes have trouble staying still when you have to push buttons or otherwise make adjustments to the device.

It seems like every time a new generation of microscopes aimed at the electronics market arrives on the scene, many of the earlier flaws get taken care of. That’s certainly the case with the Andonstar AD409-Max.

Continue reading “Hands On: AD409-Max Microscope” →

Linux Fu: The Root Cause

May 21, 2024 by Al Williams 22 Comments

There was a time when real system administrators just logged into Unix systems as root. But as we all know — with great power comes great responsibility. It’s too easy to do terrible things when you are really just trying to do normal work, and, on top of that, malicious software or scripts can do naughty things without you noticing. So common practice quickly changed to where an administrator had a personal account but then had a way to run certain programs “as root” which means you had to deliberately decide to wield your power.

Before long, people realized you don’t even need a root login account. That way, an attacker can’t try to log into root at all. Sure, they could still compromise your account, but a random hacker knows you might have a root user, but it is harder to guess that your login ID is JTKirkJr or whatever.

There are other ways to control what users can do, but many Linux and Unix installations still use this model. The root can do everything but login, and specific users get the privilege to do certain things.

Continue reading “Linux Fu: The Root Cause” →

This MIDI BoomBox Takes Floppies

May 21, 2024 by Al Williams 11 Comments

You might have had a boombox back in the 1990s, but probably not like the Yamaha MDP-10. As [Nicole] explains, the odd little device played MIDI files from a floppy disk. Technically, it wasn’t truly a boombox because it lacked batteries, but it sure looks like one.

The box also had a MIDI input jack, but no output. For an antique gadget, it is pretty impressive, but maybe not much by today’s standards. Of course, what we really wanted to see was what was inside. [Nicole] doesn’t disappoint.

The boombox brains are a pair of Hitachi H8 3000-series CPUs. The boards actually looks surprisingly modern until you notice the lack of integration. There are separate ROMs, RAMs, a floppy drive controller, and, of course, MIDI chips. Apparently, opening the box up is a challenge so [Nicole] suggests not doing it unless necessary. We assume it went back together with no problems.

There are lots of tidbits about peculiarities in the device. There are also, of course, recordings of the output and some comparisons from other devices. A great look into an old and odd piece of gear.

Since it has an input jack, you could connect it to — oh, we don’t know — maybe some spoons? Or a hurdy-gurdy.

Home Assistant Display Uses E-Ink

May 20, 2024 by Al Williams 2 Comments

[Markus] grabbed an ESP32 and created a good-looking e-ink dashboard that can act as a status display for Home Automation. However, the hardware is generic enough that it could work as a weather station or even a task scheduler.

The project makes good use of modules, so there isn’t much to build. A Waveshare 2.9-inch e-ink panel and an ESP32, along with a power supply, are all you need. The real work is in the software. Of course, you also need a box to put it in, but with 3D printing, that’s hardly a problem.

Well, it isn’t a problem unless — like [Markus] — you don’t have a 3D printer. Instead, he built a wooden case that also holds notepaper.

The software uses ESPHome to interface with Home Assistant. There is a fair amount of configuration, but nothing too difficult. Of course, you can customize the display to your heart’s content. Overall, this is a great example of how a few modular components and some open-source software can combine to make a very simple yet useful project.

There are many ways to use an ESP32 in your home automation setup. Maybe you can salvage the e-ink displays. Just try not to get carried away.

Radio Caroline At 60

May 19, 2024 by Al Williams 11 Comments

In the 1960s, if you were a teenager in the United States, a big part of your life was probably music. There was a seemingly endless supply of both radio stations and 45s to keep you entertained. In the UK and other countries, though, the government held a monopoly on broadcasting, and they were not always enthralled with the music kids liked. Where there is demand, there is an opportunity, and several enterprising broadcasters set up radio stations at sea, the so-called pirate radio stations. In 1964, Irish businessman [Ronan O’Rahilly] did just this and founded Radio Caroline. Can you imagine that 60 years later, Radio Caroline is still around?

Not that it has been in operation for 60 years in a row. There were a few years the station’s ship had been impounded by creditors. Then, the ship ran aground on the Goodwin Sands and was damaged. You can see a news short from 1965 in the video below (Radio Caroline shows up at about the 1:50 mark).

Continue reading “Radio Caroline At 60” →