Author: Jenny List

2977 Articles

The First New Long Wave Radio Station Of This Millennium

August 11, 2024 by 34 Comments

The decline of AM broadcast radio is a slow but inexorable process over much of the world, but for regions outside America there’s another parallel story happening a few hundred kilohertz further down the spectrum. The long wave band sits around the 200kHz mark and has traditionally carried national-level programming due to its increased range. Like AM it’s in decline due to competition from FM, digital, and online services, and one by one the stations that once crowded this band are going quiet. In the middle of all this it’s a surprise then to find a new long wave station in the works in the 2020s, bucking all contemporary broadcasting trends. Arctic 252 is based in Finland with programming intended to be heard across the Arctic region and aims to start testing in September.

The hack in this is that it provides an opportunity for some low-frequency DXing, and given the arctic location, it would be extremely interesting to hear how far it reaches over the top of the world into the northern part of North America. The 252KHz frequency is shared with a station in North Africa that may hinder reception for some Europeans, but those with long memories in north-west Europe will find it fairly empty as it has been vacated in that region by the Irish transmitter which used to use it.

So if you have a receiver capable of catching long wave and you think you might be in range, give it a listen. Closer to where this article is being written, long wave stations are being turned off.

Harris & Ewing, photographer, Public domain.

A Tiny Knob Keeps You In Control

August 11, 2024 by 35 Comments

There are many forms of human interface device beyond the ubiquitous keyboard and mouse, but when it comes to fine-tuning a linear setting such as a volume control there’s nothing quite like a knob. When it comes to peripherals it’s not the size that matters, as proven by  [Stefan Wagner] with the Tiny Knob. It’s a very small PCB with a rotary encoder and knob, an ATtiny85, a USB port, and not much else.

It uses the V-USB software implementation of USB HID, and should you have a need for a Tiny Knob of your own you can find all the files for it in a GitHub repository. There’s even a very professional-looking 3D-printed enclosure for the finishing touch. We like this project for its simplicity, and we think you might too.

Over the years we’ve brought you more than one knob, they appear to be a popular subject for experimentation. If you’re up for more, have a look at this one.

The Waveguide Explanation You Wish You’d Had At School

August 9, 2024 by 13 Comments

Anyone who has done an electronic engineering qualification will at some point have had to get to grips with transmission lines, and then if they are really lucky, waveguides. Perhaps there should be one of those immutable Laws stating that for each step in learning about these essential parts, the level of the maths you are expected to learn goes up in an exponential curve, for it’s certainly true that most of us breathe a hefty sigh of relief when that particular course ends. It’s not impossible to understand waveguides though, and [Old Hack EE] is here to slice through the formulae with some straightforward explanations.

First of all we learn about the basics of propagation in a waveguide, then we look at the effects of dimension on frequency. Again, there’s little in the way of head-hurting maths, just real-world explanations of cutt-off frequencies, and of coupling techniques. For the first time we’ve seen, here are simple and understandable explanations of the different types of splitter, followed up by the famous Magic T. It’s all in the phase, this is exactly the stuff we wish we’d had at university.

The world needs more of this type of explanation, after all it’s rare to watch a YouTube video and gain an understanding of something once badly taught. Take a look, the video is below the break.

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500cc Of 4-Wheel Off-Road Fun

August 9, 2024 by 9 Comments

Who among us hasn’t at some point thought of building a little vehicle, and better still, a little off-road vehicle for a few high-octane rough-terrain adventures. [Made in Poland] has, and there he is in a new video with a little off-road buggy.

The video which we’ve paced below the break is quite long, and it’s one of those restful metalworking films in which we see the finished project take shape bit by bit. In this case the buggy has a tubular spaceframe, with front suspension taken from a scrap quad and a home-made solid rear axle. For power there’s a 500cc Suzuki two-cylinder motorcycle engine, with a very short chain drive from its gearbox to that axle. The controls are conventional up to a point, though we’d have probably gone for motorcycle style handlebars with a foot shift rather than the hand-grip shift.

The final machine is a pocket drift monster, and one we’d certainly like to have a play with. We’d prefer some roll-over protection and we wonder whether the handling might be improved were the engine sprung rather than being part of a huge swing-arm, but it doesn’t appear to interfere with the fun. If you fancy a go yourself it’s surprisingly affordable to make a small vehicle, just build a Hacky Racer.

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An ESP Makes A Bicycle Odometer

August 7, 2024 by 4 Comments

If you’d like to measure the speed of your cycling then it’s easy enough to buy a cycle computer, but as [Clovis Fritzen] has done it’s also an option to build one. The result of his work is a smart PCB on which the speed is indicated with a row of LEDs.

The sensor is a straightforward affair, a reed switch with a magnet on a wheel, which is sensed by an ESP8266. The six LEDs are charlieplexeed over three lines. To keep the supply voltage correct for the ESP from the uncertain state of a lithium battery, a small buck-boost module is used. Sadly the code doesn’t seem to make the speed available via the wireless part of the processor, but we’re guessing that a bit of extra software work could fix that.

The result when put in a box on the handlebars, is a smart but simple instrument that would aid any bike. It’s by no means the first one we’ve brought you and we doubt it will be the last.

The 555 As A MOSFET Driver

August 5, 2024 by 25 Comments

To drive a MOSFET requires more than merely a logic level output, there’s a requirement to charge the device’s gate which necessitates a suitable buffer amplifier. A variety of different approaches can be taken, from a bunch of logic buffers in parallel to a specialised MOSFET driver, but [Mr. T’s Design Graveyard] is here with a surprising alternative. As it turns out, the ever-useful 555 timer chip does the job admirably.

It’s a simple enough circuit, the threshold pin is pulled high so the output goes high, and the PWM drive from an Arduino is hooked up to the reset pin. A bipolar 555 can dump a surprising amount of current, so it’s perfectly happy with a MOSFET. We’re warned that the CMOS variants don’t have this current feature, and he admits that the 555 takes a bit of current itself, but if you have the need and a 555 is in your parts bin, why not!

This will of course come as little surprise to anyone who played with robots back in the day, as a 555 or particularly the 556 dual version made a pretty good and very cheap driver for small motors. If you’ve ever wondered how these classic hips work, we recently featured an in-depth look.

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Your ESP32 As A USB Bluetooth Dongle

August 4, 2024 by 8 Comments

Using Bluetooth on a desktop computer is now such a seamless process; it’s something built-in and just works. Behind that ubiquity is a protocol layer called HCI, or Host Controller Interface, a set of commands allowing a host computer to talk to a Bluetooth interface.  That interface doesn’t have to be special, and [Dakhnod] is here to show us that it can be done with an ESP32 microcontroller through its USB interface.

The linked repository doesn’t tell us which of the ESP32 variants it works with, but since not all of them have a USB peripheral we’re guessing one of the newer variety. It works with Linux computers, and we’re told it should work with Windows too if a HCI driver is present. We might ask ourselves why such a project is necessary given the ubiquity of Bluetooth interfaces, but for us it’s provided the impetus to read up on how it all works.

We can’t find anyone else in our archive who’s made a Bluetooth dongle in this way, but we’ve certainly seen sniffing of HCI commands to reverse engineer a speaker’s communications.