The Origin Of Cut, Copy, And Paste

January 20, 2021 by Al Williams 90 Comments

I’m always fascinated that someone designed just about everything you use, no matter how trivial it is. The keyboard you type on, the light switch you turn on, even the faucet handle. They don’t just spontaneously grow on trees, so some human being had to build it and probably had at least a hazy design in mind when they started it.

Some things are so ubiquitous that it is hard to remember that someone had to dream them up to begin with. A friend of mine asked me the other day why we use Control+X and Control+V to manipulate the clipboard almost universally. Control+C for copy makes sense, of course, but it is still odd that it is virtually universal in an industry where everyone likes to reinvent the wheel. I wasn’t sure of the answer but figured it had to do with some of the user interface standards from IBM or Sun. Turns out, it is much older than that.

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Cura Plugin Offers Custom Support

January 19, 2021 by Al Williams 7 Comments

[Chuck] likes the ability of Simplify3D to add support to parts of a model manually. However, not everyone wants to spend $150 for a slicer, so he’s shared how to install a plugin that allows you to do the same trick in Cura.

The plugin is “Cylindric Custom Support.” That doesn’t sound very exciting, but you get five choices of shapes you can create custom supports easily. There are also size and angle parameters you can use to customize the effect.

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Q Multiplier — Er… Multiplies Q

January 18, 2021 by Al Williams 13 Comments

If you are below a certain age, you’ve probably never heard of a Q multiplier. This is a device that increases the “Q” of a radio receiver’s intermediate frequency and, thus, provide a higher selectivity. If you enjoy nostalgia, you can see inside a 1960s-era Heathkit QF-1 Q multiplier in [Jeff’s] informative video, below.

The Q multiplier was a regenerative amplifier that operated at just below the oscillation point. This provided very high amplification for the frequency of interest and less amplification for other frequencies. Some radios had a stage like this built-in, but the QF-1 was made to add into an external radio. For some Heathkit receivers, there was a direct plug to tap into the IF stage for this purpose. Othe radios would require some hacking to get it to work.

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LEDs From Dubai: The Royal Lights You Can’t Buy

January 17, 2021 by Al Williams 104 Comments

[Clive] had an interesting video about LED lights from Philips. You can’t buy them unless you live in Dubai. Apparently inspired by the ruler of Dubai, Sheikh Mohammad Bin Rashid Al Maktoum, who wanted more efficient and longer-lasting bulbs. The secret? A normal LED bulb uses an LED “filament” at 1 watt each. The Dubai bulbs run at about a fourth of that which means they need more LEDs to get the same amount of light, but they should last longer and operate more efficiently.

After exploring the brightness and color of different lamps, [Clive] tears one up and finds some surprises inside. The LEDs get over 200V each and the driver circuit has a lot of pairs of components, possibly to keep the size small for the high voltages involved, although it could be to improve reliability, [Clive] wasn’t sure.

By reducing the power, [Clive] was able to count that each LED strip contains 21 LEDs. He also notes some of the oddities in construction that appear to be for reliability and ease of manufacturing. We aren’t sure how that compares to the construction of conventional bulbs. The circuit includes a bridge rectifier and a linear current regulator using a MOSFET.

The bulbs cost a bit more, but if you factor in the probable long life, their total cost over time should be reasonable. Overall, it is interesting that a nice design came from what amounts to government regulation. Of course, there is a price: in exchange for the development of the bulbs, Philips has the exclusive right to make and sell the bulbs for the next several years. They expect to sell 10 million lamps by the end of 2021, although they are only available, currently, in Dubai.

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Unknown Quantum Effect Makes Insulator Oscillate

January 17, 2021 by Al Williams 22 Comments

If there are two classes of matter that electronics people can agree on, its conductors and insulators. Electrically, conductors and insulators don’t have much in common. The same has held true in the quantum physics world until some research at Princeton has suggested that quantum oscillation — a phenomenon associated with metals — is taking place in an insulator. Scientists aren’t sure what’s really happening yet, but it may suggest there is a new quantum particle yet to be discovered.

In metals, electrons are very mobile which allows a relatively easy flow of electrical current. However, at low temperatures, a magnetic field can shift electrons to a quantum state causing its resistance to change in an oscillating pattern. Insulators generally do not exhibit this effect.

Researchers made a monolayer of tungsten ditelluride using the same kind of adhesive tape process you see to create graphene. In bulk, the material is a conductor but in a monolayer, tungsten ditelluride is an insulator.

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Circuit VR: Even More Op Amps

January 15, 2021 by Al Williams 23 Comments

In the last Circuit VR we looked at some basic op amp circuits in a simulator, including the non-inverting amplifier. Sometimes you want an amplifier that inverts the signal. That is a 5V input results in a -5V output (or -10V if the amplifier has a gain of 2). This corresponds to a 180 degree phase shift which can be useful in amplifiers, filters, and other circuits. Let’s take a look at an example circuit simulated with falstad.

Remember the Rules

Last time I mentioned two made up rules that are good shortcuts for analyzing op amp circuits:

The inputs of the op amp don’t connect to anything internally.
The output mysteriously will do what it can to make the inputs equal, as far as it is physically possible.

As a corollary to the second rule, you can easily analyze the circuit shown here by thinking of the negative (inverting) terminal as a virtual ground. It isn’t connected to ground, yet in a properly configured op amp circuit it might as well be at ground potential. Why? Because the + terminal is grounded and rule #2 says the op amp will change conditions to make sure the two terminals are the same. Since it can’t influence the + terminal, it will drive the voltage through the resistor network to ensure the – terminal is at 0V.

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Programmable Filament For Multicolor Printing

January 15, 2021 by Al Williams 29 Comments

A recent research paper shows a way to create multicolor 3D prints using a single extruder if you are too lazy to babysit the machine and switch filament. The concept: print your own “programmable” filament that has the right colors in the right place. This is the same idea as manually splicing filament but presumably is more efficient since the process works with one color at a time and doesn’t repeat. In other words, to print the 64 squares of a chessboard you’d swap filament at least 64 times on each layer. Using programmable filament, you’d load one spool, print half of the filament, load another spool, print the other half, and then finally load the newly created filament and print the chessboard. Notice that the first two operations aren’t printing the chessboard. They are printing the spool of filament you feed through on the third pass.

There are machines made to do this, of course, although they generally just splice lengths of filament together for you automatically. Using one filament solves the problems of keeping multiple heads in alignment as well as the added cost and complexity. However, you now have different problems such as the transition between materials and knowing exactly how much material will be at each point in the print.

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