Active Ideal Full Bridge Rectifier Using TEA2208T

December 27, 2025 by Maya Posch 4 Comments

Everyone loves a full-wave bridge rectifier, but there’s no denying that they aren’t 100% efficient due to the diode voltage drop. Which isn’t to say that with some effort we cannot create an ideal bridge rectifier using active components, as demonstrated by [Mousa] with an active bridge circuit. This uses the NXP TEA2208T active bridge rectifier controller, along with the requisite four MOSFETs.

Comparing a diode bridge rectifier with an active bridge rectifier. (Credit: Mousa, YouTube)

Taking the circuit from the datasheet, a PCB was created featuring four FDD8N50NZ MOSFETs in addition to the controller IC. These were then compared to a diode-based bridge rectifier, showing the imperfections with the latter when analyzing the output using an oscilloscope.

As expected, the active rectifier’s output was also one volt higher than the diode bridge rectifier, which is another small boost to overall efficiency. According to NXP’s product page, there’s about a 1.4% efficiency gain at 90 VAC, with the chip being promoted for high-efficiency operations. When you consider that many designs like computer PSUs feature one or more diode bridge rectifiers often strapped to heatsinks, the appeal becomes apparent. As for [Mousa], he put this particular board in his laboratory PSU instead of the diode bridge rectifier, because why not.

Perhaps the biggest impediment to using an active rectifier is the cost, with the TEA2208T coming in at $4 on DigiKey for a quantity of 100, in addition to the MOSFETs, PCB, etc. If power efficiency isn’t the goal, then some wasted power and an aluminium heatsink is definitely cheaper.

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Print Your Next LED Bezel

December 27, 2025 by Donald Papp No comments

LED bezels (also known as LED panel-mount holders) are great, so how about 3D printing the next ones you need? Sure, they’re inexpensive to purchase and not exactly uncommon. But we all know that when working on a project, one doesn’t always have everything one might need right at hand. At times like that, 3D printing is like a superpower.

Printing a part you find yourself short of can be a lifesaver.

[firstgizmo]’s design is made with 3D printing in mind, and most printers should be able to handle making them. Need something a little different? You’re in luck because the STEP files are provided (something we love to see), which means modifications are just a matter of opening them in your favorite CAD program.

There’s not even any need to export to an STL after making tweaks, because STEP support in slicer programs is now quite common, ever since PrusaSlicer opened that door a few years ago.

Not using 5 mm LEDs, and need some other size? No problem, [firstgizmo] also has 3 mm, 8 mm, and 10 mm versions so that it’s easy to mount those LEDs on a panel. Combined with a tool that turns SVG files into multi-color 3D models, one can even make some panels complete with color and lettering to go with those LEDs. That might be just what’s needed to bring that midnight project to the next level.

Building A Wall-Mounted Sound Visualizer

December 27, 2025 by Lewin Day 4 Comments

Visualizers used to be very much in vogue, something you’d gasp in at amazement when you’d fire up Winamp or Windows Media Player. They’re largely absent from our modern lives, but [Arnov Sharma] is bringing them back. After all, who doesn’t want a cool visualizer hanging on the wall in their living room?

The build is based around the Raspberry Pi Pico 2. It’s paired with a small microphone hooked up to a MAX9814 chip, which amplifies the signal and offers automatic gain control to boot. This is a particularly useful feature, which allows the microphone to pick up very soft and very loud sounds without the output clipping. The Pi Pico 2 picks up the signals from the mic, and then displays the waveforms on a 64 x 32 HUB75 RGB matrix. It’s a typical scope-type display, which allows one to visualize the sound waves quite easily. [Arnov] demonstrates this by playing tones on a guitar, and it’s easy to see the corresponding waveforms playing out on the LED screen.

It’s a fun project, and it’s wrapped up in a slick 3D printed housing. This turns the visualizer into a nice responsive piece of wall art that would suit any hacker’s decor. We’ve featured some other great visualizers before, too. Continue reading “Building A Wall-Mounted Sound Visualizer” →

Drunken EBay Purchase Becomes Motorized, Speaking Dalek

December 26, 2025 by Donald Papp 7 Comments

Not every impulsive purchase on eBay leads to possession of a wooden Dalek, but when a friend did exactly that, [Tony Goacher] did his part to turn ‘Dalek Bob’ into a motorized and remote-controlled unit of impressive stature.

Fitting wheels to shafts and motors to a frame can be a bit tricky when none were made with the other in mind.

The purchased Dalek is made of wood and, with the help of two bolts, is of sufficient size to trap a human inside. There’s a bench of sorts upon which the captive can sit, and with some effort, shuffle the surrounding frame awkwardly about. The scale of the Dalek is impressive, but it was clear the effect of human-powered locomotion was lacking. The solution was to install wheelchair motors, tires, and an ESP32-based remote control.

Quite a lot of work went into mounting the motors and wheels, and the challenges will be familiar to anyone who has done hobby robotics. One can choose ideal motors and wheels, but making them fit one another can be an entirely different story. Shafts and hubs are of different sizes, motor mounting doesn’t quite match the platform, and it’s all a bit like fitting a square peg into a round hole. But with access to the right tools, it’s nothing a little metalwork and welding can’t solve.

For the control system, the ESP32 (with a beautiful CNC-routed custom PCB) sets itself up as a wireless access point that serves a web-based control panel for piloting, and controls two H-bridges to drive the motors. What’s more, it also provides a sound board from which a second operator can trigger appropriate phrases and sounds from the Dalek.

Some folks prefer their remote-controlled Daleks plush and cute instead of large and looming, but we like the smooth movement and imposing stature of this one. Watch it all in action in the video, embedded below.

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Simulating Driven-Dissipative Quantum Spin Dynamics On Consumer Hardware

December 26, 2025 by Maya Posch 3 Comments

Physics simulations using classical mechanics is something that’s fairly easily done on regular consumer hardware, with real-time approximations a common feature in video games. Moving things to the quantum realm gets more complex, though with equilibrium many-body systems still quite solvable. Where things get interesting is with nonequilibrium quantum systems.

These open systems are subject to energy gains and losses that disrupt its equilibrium. The truncated Wigner approximation (TWA) is used as a semi-classical method to solve these, but dissipative spin systems proved tricky. Now however [Hosseinabadi] et al. have put forward a TWA framework (PR article) for driven-dissipative many-body dynamics that works on consumer hardware.

Naturally, even with such optimizations there is still the issue that the TWA is only an approximation. This raises questions such as about how many interactions are required to get a sufficient level of accuracy.

Using classical computers to do these kind of quantum physics simulations has often been claimed to the ideal use of qubit-based quantum computers, but as has been proven repeatedly, you can get by with a regular tensor network or even a Commodore 64 if you’re in a pinch.

Mini Battery-Powered Vapor-Compression Air Conditioner

December 26, 2025 by Maya Posch 15 Comments

The brushless DC-powered compressor. (Credit: Hyperspace Pirate, YouTube)

When you think of air conditioners, you tend to think of rather bulky units, with the window-mounted appliances probably among the most compact. There’s however no real minimum size limit to these AC units, as long as you can get an appropriate compressor. If you also manage to pick up a small, DC-powered compressor like [Hyperspace Pirate] did, then you might be tempted to make a hand-portable, battery-powered AC unit.

At their core vapor-compression AC units are very simple, featuring the aforementioned compressor, a condensing coil, expansion valve and the evaporator coil. Or in other words, some radiators looted out of other devices, various plumbing supplies and the refrigerant gas to charge the AC unit with.

Since the compressor uses a BLDC motor, it has three terminals that a typical ESC connects to, along with two 2200 mAh Li-on battery packs that can keep the portable AC unit running for a while.

As for the refrigerant gas, although the compressor lists R134a, this is both quite expensive and illegal in parts of the world like the EU. Alternatives are butane (R600) as well as isobutane (R600a), but due to unfortunate circumstances the use of propane (R290) was forced. Fortunately this worked fine, and after some testing and running of numbers it was found that it had about 42 Watt cooling power, with a coefficient of performance (COP) of around 1.

Considering that most AC units have a COP of 3.5 – 5, this shows that there’s still some room for increased efficiency, but at the very least this portable, battery-powered AC unit provides cold air on one side, and hot air on the other while completely blowing Peltier thermocouples out of the water in terms of efficiency.

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Pocket-sized Test Pattern Generator Helps Check Those CRTs

December 26, 2025 by Donald Papp 21 Comments

[Nicholas Murray]’s Composite Test Pattern Generator is a beautifully-made, palm-sized tool that uses an ESP32-based development board to output different test patterns in PAL/NTSC. If one is checking out old televisions or CRTs, firing up a test pattern can be a pretty handy way to see if the hardware is healthy or not.

The little white add-on you see attached to the yellow portion is a simple circuit (two resistors and an RCA jack) that allows the microcontroller to output a composite video signal. All one needs to do is power on the device, then press the large button to cycle through test patterns. A small switch on the side toggles between NTSC and PAL video formats. It’s adorable, and makes good use of the enclosures that came with the dev board and proto board.

In a pinch a hacker could use an original Raspberry Pi, because the original Pi notably included a composite video output. That feature made it trivial to output NTSC or PAL video to a compatible display. But [Nicholas]’s device has a number of significant advantages: it’s small, it’s fast, it has its own battery and integrated charger, and the little color screen mirroring the chosen test pattern is a great confirmation feature.

This is a slick little device, and it’s not [Nicholas]’s first test pattern generator. He also created a RP2040-based unit with a VGA connector, the code of which inspired a hacker’s home-grown test pattern generator that was used to service a vintage arcade machine.