Author: Jenny List

3032 Articles

A Low Voltage Solder Gun From Scratch

January 27, 2025 by 15 Comments

We’re used to those high voltage projects which use a self-oscillating transformer circuit with a TV flyback winding, and we have even at times railed against them for their inefficiency compared to a real flyback circuit using the same parts. But what happens if the same idea is used to create a low voltage instead of a high one? [D. Creative] has a soldering gun project doing just this, making a low voltage at a very high current.

The video of the project is below the break, and while electrically it’s nothing unexpected, we’re taken by the quality of the build. All the parts come from scrap electronics, the main transformer is three ferrite cores with a piece of copper busbar as the secondary. The circuitry is built dead bug style, and it’s housed in a gun-style case made by hand from sheet Perspex. It takes 12 volt power from a laptop power supply, and feeds it to the oscillator which is perched up at the back of the device. The transformer fits in the “barrel”, and a pair of large capacitors fit in the handle. We expect it to get hot, but the duty cycle on these devices in use is probably low enough to keep it from melting.

We like anything that uses scrap parts to make something useful, and we’re particularly taken with the casing of this one. It looks as though the parts come from old switch mode power supplies, something we’ve been known to rob ourselves.

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The FTC Take Action, Is Time Finally Up For John Deere On Right To Repair?

January 27, 2025 by 44 Comments

Over the last decade we have brought you frequent reports not from the coolest of hackerspaces or the most bleeding edge of engineering in California or China, but from the rolling prairies of the American Midwest. Those endless fields of cropland waving in the breeze have been the theatre for an unlikely battle over right to repair, the result of which should affect us all. The case of FEDERAL TRADE COMMISSION, STATE OF ILLINOIS, and STATE OF MINNESOTA, v. DEERE & COMPANY  relates to the machinery manufacturer’s use of DRM to restrict the repair of its products, and holds the promise to end the practice once and for all.

This is being written in Europe, where were an average person asked to name a brand that says “America”, they might reach for the familiar; perhaps Disney, McDonalds, or Coca-Cola. These are the flag-bearers of American culture for outsiders, but it’s fair to say that none of them can claim to have built the country. The green and yellow Deere tractors on the other hand represent the current face of a company with nearly two hundred years of farming history, which by virtue of producing some of the first mass-produced plows, had perhaps the greatest individual role in shaping modern American agriculture and thus indirectly the country itself. To say that Deere is woven into the culture of rural America is something of an understatement, agricultural brands like Deere have an enviable customer base, the most loyal of any industry.

Thus while those green and yellow tractors are far from the only case of DRM protected repairability, they have become the symbolic poster child for the issue as a whole. It’s important to understand then how far-reaching it is beyond the concerns of us technology and open-source enthusiasts, and into something much more fundamental. Continue reading “The FTC Take Action, Is Time Finally Up For John Deere On Right To Repair?” →

Making A Mini AM Transmitter Better

January 26, 2025 by 32 Comments

The chances are that many of you will have made an FM “bug” style transmitter, a simple one-transistor oscillator usually driven by a small electret microphone. It’s also relatively straightforward to do the same for AM, and if you take a look through AliExpress you’ll find some modules which do just that. [Doz Television Workshop] has one, and he’s treated us to a thorough run-down of its design before addressing some of its shortcomings.

An AM transmitter is simple enough, in this case an oscillator and buffer driving a class C power amplifier. The modulation is applied by a transistor in series with the power amp, driven from an audio amplifier. Some attention has gone into the design of this one, with a proper output filter and plenty of room for tweaking to achieve proper levels and modulation density. There are some problems though — The modulator transistor is mounted upside down for the heatsink, and the frequency stability leaves something to be desired. [Doz] fixes the heatsink mounting and incorporates a DDS frequency synthesizer with an Arduino for control.

More after the break…

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The ESP32-C5, Finally Espressif Goes Dual-Band

January 26, 2025 by 20 Comments

The ESP32 series of microcontrollers have been with us for quite a few years now, providing a powerful processor and wireless connectivity for not a huge outlay. We’ve seen a bunch of versions over the years with both Tensilica and RISC-V cores, but so far the ones with radios have all only serviced 2.4 GHz WiFi. That’s about to change to include 5GHz with the new C5 variant though, and [Andreas Spiess] has been lucky enough to get his hands on a prototype dev kit

It’s very similar to the C6, which we’re already used to beyond the dual-band 2.4GHz and 5GHz radio from a software point of view. The C5 is so new that the company has yet to incorporate the new chip into the Arduino IDE. He shows it working and detecting both networks though, and speculates a little about its eventual marketing.

Interesting to us is the dual-band antenna, with branches for both frequencies on the same PCB. We’d be interested to see the real-world performance of this, and also whether they produce a version with separate outputs for each band. The full video is below the break. In the meantime, watch out for this chip appearing on the market.

It’s not the only Espresif chip we’re anticipating at the moment.

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A Waist Level Viewfinder For Not A Lot

January 26, 2025 by 8 Comments

Photographic accessories are often plagued by high prices, as photography is considered a rich man’s game. It doesn’t have to be that way though, and [Snappiness] is here to get you started on the route to cheaper kit with a waist-level viewfinder project.

If you’ve used a twin-lens reflex camera then you should be familiar with a waist level viewfinder, it’s a lens and mirror arrangement allowing the photographer to frame the shot looking down from above. Modern cameras often have no viewfinder, so this is aimed at digital compacts without flip-up screens.

It has three components, all available for relatively low prices, and mounted in a 3D printed case. There’s a prime lens, a mirror, and a Fresnel lens forming the part the photographer looks through. It’s a simple device, but still one which would cost a lot more off the shelf. The video is below the break.

It might interest you to know that this is not the first viewfinder project we’ve brought you for digital cameras.

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Does A Radome Affect Radio?

January 25, 2025 by 24 Comments

Not too far away from where this is being written is one of Uncle Sam’s NATO outposts, a satellite earth station for their comms system. Its most prominent feature is a radome, a huge golf-ball-like structure visible for miles, that protects a large parabolic antenna from the British weather. It makes sense not just for a superpower to protect its antennas from the elements, and [saveitforparts] is doing the same with a geodesic dome for his radio telescope experiments. But what effect does it have on the received signal? He’s made a video to investigate.

The US military radome is likely constructed of special RF-transparent materials, but this smaller version has a fibreglass skin and an aluminium frame. When he compares internal and external sky scans made with a small motorised satellite TV antenna he finds that the TV satellites are just as strong, but that the noise floor is higher and the frame is visible in the scan. It’s particularly obvious with such small dish, and his planned larger array should improve matters.

We would be curious to know whether an offset-fed dish constructed to minimise ground noise reaching the LNB, would improve matters further. It’s no surprise that the frame doesn’t impede the TV satellites though, as it is many wavelengths wide at that frequency. The video is below the break, and meanwhile, we featured the antenna he’s using here in 2023.

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Soviet Wired Radio, How It Worked

January 25, 2025 by 39 Comments

At the height of the Cold War, those of us on the western side of the wall had plenty of choice over our radio listening, even if we stuck with our country’s monolithic broadcaster. On the other side in the Soviet Union, radio for many came without a choice of source, in the form of wired radio systems built into all apartments. [Railways | Retro Tech | DIY] grew up familiar with these wired radios, and treats us to a fascinating examination of their technology, programming, and ultimate decline.

In a Soviet apartment, usually in the kitchen, there would be a “Radio” socket on the wall. Confusingly the same physical dimension as a mains socket, it carried an audio signal. The box which plugged into it was referred to as a radio, but instead contained only a transformer, loudspeaker, and volume control. These carried the centralised radio station, piped from Moscow to the regions by a higher voltage line, then successively stepped down at regional, local, and apartment block level. A later refinement brought a couple more stations on separate sub-carriers, but it was the single channel speakers which provided the soundtrack for daily life.

The decline of the system came over the decades following the end of communism, and he describes its effect on the mostly older listenership. Now the speaker boxes survive as affectionate curios for those like him who grew up with them.

You probably won’t be surprised to find twisted-wire broadcasting in use in the West, too.

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