Wien Bridge Oscillator Drives Distortion Into The Floor

September 8, 2023 by 12 Comments

It’s not often that a single photo can tell you pretty much everything you need to know about a project, but the spectrum analyzer screenshot nearby is the perfect summary of this over-the-top low-distortion audio oscillator build. But that doesn’t mean there’s not a ton of interesting stuff going on with this one, so buckle up.

One spike at the fundamental and not much more.

The project is by [Basin Street Design], who doesn’t really offer much by way of inspiration for this undertaking, nor a discussion on what this will be used for. But the design goals are pretty clear: build an oscillator with as little distortion as possible across the audio frequency range.

The basic circuit is the well-known Wien bridge oscillator where the R-C pairs are switched in and out of the feedback loop to achieve frequency range control. This was accomplished with rotary switches rebuilt from their original configuration in a Heathkit IG-18 sine/square wave generator, a defunct instrument that was gutted and used as an enclosure for this build. There are a lot of other treats here, too, like the automatic gain control (AGC) that uses a homebrew voltage-controlled resistor made from an incandescent lamp and a cadmium sulfide photoresistor glued inside a piece of brake line, and an output attenuator made from discrete resistors that drops the output in 10 dB steps while maintaining an overall 75-Ohm impedance.

But at the end of the day, it all comes down to that single spike on the spectrum analyzer, with no apparent harmonics. To make sure there wasn’t something hiding down in the noise, [Basin Street] added a notch filter to lower the fundamental by 60 dB, allowing the spectrum analyzer sensitivity to be cranked way up. Harmonics were visible, but so far down into the noise — as low as -115 dBc — that it’s hardly worth mentioning.

There’s a lot more detail in this one, so dive in and enjoy. If you want another take on Wien bridge circuits, check out this recent LM386-based oscillator. Just don’t expect such low distortion with that one.

An aluminum box sits on a workbench. It is open and has a message saying "I Love You!" inserted in a wooden slot. There is a switch with a yellow LED on the front and a small compartment to the left of the wooden slot to store paper.

Share Your Feelings Like A Spy

September 8, 2023 by 13 Comments

While hackers can deftly navigate their way through circuit diagrams or technical documentation, for many of us, simple social interactions can be challenge. [Simone Giertz] decided to help us all out here by making a device to help us share our feelings.

Like an assignment in Mission: Impossible, this aluminum box can convey your confessions of love (or guilt) and shred them after your partner (or roommate) reads the message. The box houses a small shredder and timer relay under a piece of bamboo salvaged from a computer stand. When the lid is opened, a switch is depressed that starts a delay before the shredder destroys the message. The shredder, timer, and box seem almost made for each other. As [Giertz] says, “Few things are more satisfying than when two things that have nothing to do with each other, perfectly fit.”

While seemingly simple, the attention to detail on this build really sets it apart. The light on the front to indicate a message is present and the hinged compartment to easily clean out shredded paper really make this a next-level project. Our favorite detail might be the little space on the side to store properly-sized paper and a marker.

While the aluminum box is very industrial chic, we could see this being really cool in a vintage metal lunch box as well. If you’re looking for other ways to integrate feelings and technology, checkout how [Jorvon Moss] brings his bots to life or how a bunch of LEDs can be used to express your mood.

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[Thomas Sanladerer]’s YouTube Channel Goes In The Toilet

September 7, 2023 by 28 Comments

We like [Thomas Sanladerer], so when we say his channel has gone in the toilet, we mean that quite literally. He had a broken toilet and wanted to compare options for effecting a 3D printed repair. The mechanism is a wall-mounted flush mechanism with a small broken plastic part. Luckily, he had another identical unit that provided a part that wasn’t broken.

The first attempt was to 3D scan the good part. The first scanner’s software turned out to be finicky, and [Thomas] finally gave up on it. He finally used a handheld scanner which took about a half hour. It wasn’t, of course, perfect, so he also had to do some more post-processing.

The next step was to make measurements and draw the part in CAD. It took the same amount as the scan, and it is worth noting that the part had curves and angles — it wasn’t just a faceplate. The printed results were good, although a measurement error made the CAD model bind a bit instead of pivoting the way it should. The scan, of course, got it right.

A quick revision of the design solved that problem but, of course, it added some time to the process. At the end, he noticed that the scanned “good” part was also broken but in a different way. He added the additional part, which didn’t seem to bother the function. The scanned object required a little trimming but nothing tremendous.

In the end, the scanning was a bit quicker, partly because it didn’t suffer from the measurement error. However, [Thomas] noted that it was more fun to work in CAD. We thought the results looked better, anyway. [Thomas] thinks the scanners, at least the budget ones, are probably better for just getting reference objects into CAD to guide you when you create the actual objects to print.

It isn’t hard to make a cheap scanner. Some of the open designs are quite sophisticated.

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Triso Fuel And The Rolls Royce Of Nuclear Reactors

September 7, 2023 by 59 Comments

Bangor University scientists think that the way to go big with nuclear power is to, in fact, go small. Their tiny nuclear fuel pellets called triso fuel are said to be the size of poppy seeds and are meant to power a reactor by Rolls Royce the size of a “small car.” We aren’t sure if that’s a small Rolls Royce or a small normal car.

The Welsh university thinks the reactor has applications for lunar bases, here on Earth, and even on rockets because the reactor is so small. We can’t tell if the fuel from Bangor is unique or if it is just the application and the matching reactor that is making the news. Triso fuel — short for tri-structural isotropic particle fuel — was developed in the 1960s, and there are multiple projects worldwide gearing up to use this sort of fuel.

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How Small Can The ESP32 Get?

September 7, 2023 by 25 Comments

At its core, the ESP32 chip is not much more than an integrated circuit, a huge mass of transistors sealed inside an epoxy resin package with some leads. Of course, most of us won’t buy discrete ESP32 chips with no support circuitry since it’s typically easier and often not that much more expensive to get them paired with development boards of some type for easy access to things like USB and GPIO. But these tiny chips need little in the way of support to get up and running as [Paul] demonstrates with this tiny ESP32 board.

The project started as a challenge for [Paul] to build the smallest ESP32 that would still function. That means carving away nearly everything normally found accompanying one of these chips. There is no charging circuitry, only one of the GPIO pins is accessible, and it even foregoes the WiFi antennas which eliminates the major reason most people would reach for this chip in the first place. But at this form factor even without wireless capabilities it still blows other chips of this stature, like the ATtiny series, out of the water.

Even though [Paul] built it as a challenge, it goes a long way to demonstrate what’s really needed to get one of these chips up and running properly. And plenty of projects don’t need a ton of I/O or Wi-Fi either, so presuming these individual chips can be found cheaply and boards produced for various projects its an excellent way to minimize size and perhaps even power requirements. You can make these boards even smaller than a USB-A connector if you want to take this process even further, too.

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Programming A Poker Game With GPT Help

September 7, 2023 by 10 Comments

Although ChatGPT generated a huge amount of hype around replacing white collar workers completely when it was first released to the public, the general consensus now is that it won’t outright replace anyone yet, but rather people who know how to use it as a tool will replace those who don’t. Getting started with it is not too hard, either, but you’ll of course need a project to work on to familiarize yourself with the tool. [Volos Projects] gave himself the challenge of writing a poker game using ChatGPT not as the opposing player, but as a co-designer in order to learn more about it as an assistant.

The poker game is being built on an ESP32 board with a built-in AMOLED screen. Five buttons are wired to the microcontroller to allow the player to select which cards to discard and which to keep. The bet for each hand can be raised or lowered much like the tabletop poker games often seen in bars and restaurants. To program it, though, ChatGPT was used to help design the code at each step of the way, first describing the overall goal and then building each function one-by-one like shuffling the deck, dealing the hand, and then replacing and dealing new cards.

For anyone who hasn’t yet explored using ChatGPT to help design their programming projects, this effort goes a long way to showing just how useful a tool it can be. For more complex tasks, though, it does take a little bit of knowledge on the part of the user because ChatGPT can often turn out nonsense or factually inaccurate information, but at least in a programming environment you’ll generally find out quickly when that happens. It’s not just a useful tool for writing programs, either. It can accomplish a lot of ancillary tasks related to programming as well, even if it’s not writing the code directly.

Thanks to [Peter] for the tip!

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2023 Cyberdeck Challenge: The Best Decks On The Net

September 7, 2023 by 2 Comments

It was an easy decision to run a Cyberdeck Challenge in 2023 — after all, it was far and away one of our most popular contests from last year. But what was much harder was sorting out the incredible array of bespoke computers that readers have been sending in for the last few months.

Our judges have painstakingly whittled down the list of entries to get our top three winners, each of which will be awarded $150 in credit from the good folks over at DigiKey. But there were simply too many fantastic custom computers in the running to let everyone else go home empty-handed, so we’ve decided to also break out some $50 Tindie gift cards for the decks that best exemplified this year’s special categories.

Without further ado, let’s take a tour through the judge’s top picks for this year’s Cyberdeck Challenge!

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