Schrödinger Quantum Percolator Makes Half Decent Coffee

I couldn’t decide between normal and decaffeinated coffee. So to eliminate delays in my morning routine, and decision fatigue,  I’ve designed the Schrödinger Quantum Percolator — making the state of my coffee formally undecidable until I drink it.

At its core, the Quantum Percolator contains a novel quantum event detector …read more

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This Vintage Op-Amp Opens A Fascinating Window Into Semiconductor History

We have covered enough of the work of [Ken Shirriff] on these pages to know that when he publishes something, it will be a fascinating read and work of the highest quality. And so it is with his latest, a very unusual op-amp on which he performs his usual reverse …read more

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Radiation Detector Eschews Tubes, Uses Photodiode

When the topic is radiation detection, thoughts turn naturally to the venerable Geiger-Müller tube. It’s been around for ages, Russian surplus tubes are available for next to nothing, and it’s easy to use. But as a vacuum tube it can be somewhat delicate, and the high voltages needed to run …read more

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A Drum Set In Your Pocket

Cargo pants can fit drumsticks in the pockets if you don’t mind them sticking out. They can also hold this drum set and still have enough room for a pair of headphones, some pens, and a small notebook. At least, guy’s cargo pants can fit all that. Now your pocket is decked out with enough music gear to compose and drum few drum loops and even scribble some notes. We can’t speak for [Tomash Ghz] carrying a notebook, but he wanted a drum set in his pocket badly enough to make a custom circuit board to bring to the 2017 …read more

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What’s the Difference? Ask an Op Amp

If you’ve ever wondered why an op amp has the little plus and minus symbols on it, its because at the heart of it, the device is a differential amplifier. The problem is that — ideally, at least — it has infinite gain so it works like a comparator and that’s not what you usually want. So we put resistors around the thing to constrain it and get useful amplification out of it. [Stephen Mendes] does the analysis for you about how the standard configuration for a differential amplifier works. He assumes you know the stock formulae for the inverting …read more

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Op Amps Before Transistors: A 600V Vacuum Tube Monster

Op amps. Often the first thing that many learn about when beginning the journey into analog electronics, they’re used in countless ways in an overwhelmingly large array of circuits. When we think about op amps, images of DIPs and SOICs spring to mind, with an incredibly tiny price tag to boot. We take their abundance and convenience for granted nowadays, but they weren’t always so easy to come by.

[Mr Carlson] serves up another vintage offering, this time in the form of a tube op amp. The K2-W model he acquired enjoyed popularity when it was released as one of …read more

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The Hot and Cold of Balanced Audio

A few summers of my misspent youth found me working at an outdoor concert venue on the local crew. The local crew helps the show’s technicians — don’t call them roadies; they hate that — put up the show. You unpack the trucks, put up the lights, fly the sound system, help run the show, and put it all back in the trucks at the end. It was grueling work, but a lot of fun, and I got to meet people with names like “Mister Dog Vomit.”

One of the things I most remember about the load-in process was running …read more

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Ken Shirriff Found Butterflies In His Op-Amp

In 1976, Texas Instruments came out with the TL084, a four JFET op-amp IC each with similar circuitry to Fairchild’s very popular single op-amp 741. But even though the 741 has been covered in detailed, when [Ken Shirriff] focused his microscope on a TL084, he found some very interesting things.

To avoid using acid to get at the die, he instead found a ceramic packaged TL084 and pried off the cover. The first things he saw were four stabilizing capacitors, by far the largest structures on the die and visible to the naked eye.

When he peered into his microscope …read more

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A Guide To Audio Amps For Radio Builders

For hams who build their own radios, mastering the black art of radio frequency electronics is a necessary first step to getting on the air. But if voice transmissions are a goal, some level of mastery of the audio frequency side of the equation is needed as well. If your signal is clipped and distorted, the ham on the other side will have trouble hearing you, and if your receive audio is poor, good luck digging a weak signal out of the weeds.

Hams often give short shrift to the audio in their homebrew transceivers, and [Vasily Ivanenko] wants to …read more

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The Pros and Cons of Microcontrollers for Boost Converters

It never fails — we post a somewhat simple project using a microcontroller and someone points out that it could have been accomplished better with a 555 timer or discrete transistors or even a couple of vacuum tubes. We welcome the critiques, of course; after all, thoughtful feedback is the point of the comment section. Sometimes the anti-Arduino crowd has a point, but as [Great Scott!] demonstrates with this microcontroller-less boost converter, other times it just makes sense to code your way out of a problem.

Built mainly as a comeback to naysayers on his original boost-converter circuit, which relied …read more

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