Optical Guitar Pickup Works With Nylon Strings

March 4, 2024 by Lewin Day 68 Comments

Electric guitar pickups rely on steel strings interfering with a magnetic field, the changes in which are picked up with coils of wire. That doesn’t work with nylon strings, because they don’t tend to perturb magnetic fields nearly as much, beyond some infinitesimal level that some quantum physicist could explain. So what do you do? You follow [Simon]’s example, and build an optical pickup instead.

The concept is simple. You place an LED and a phototransistor in a U-shaped channel, and place it so that the string runs through it. You repeat this for each string. Thus, as a string vibrates, it interrupts the light travelling from the LED to the phototransistor. This generates a voltage that varies with the frequency of the string’s vibration. Funnily enough, this type of pickup will work just fine on both nylon and steel strings, if you were so inclined to try it.

[Simon] designed a nifty PCB with six LED-phototransistor pairs (using off-the-shelf interruptor sensors) for use with a nylon-stringed guitar. He reports that sound from the strings comes through clearly, but that there is some noise that is evident in the pickup’s output, too. Listening to the demo, it seems to capture the sound of the nylon strings well, it’s just a shame that the noise floor is so high.

If you prefer your guitar pickups to be the regular magnetic kind, you can always wind your own from scrap. Demo after the break.

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Making A Dye-Sensitized Solar Cell Is Almost DIY-able

February 28, 2024 by Lewin Day 9 Comments

We see plenty of solar projects here on Hackaday, but they primarily consist of projects that use an off-the-shelf solar panel to power something else. We see very few projects where people actually create their own solar panels. And yet, that’s precisely what [Shih Wei Chieh] has done!

The project consists of a large dye-sensitized solar panel. These are a type of solar panel that can easily be created by the DIY builder, though their efficiency leaves something to be desired versus the best commercial types available. However, you can build them in any way you like to suit your application, which can have some potential benefits.

It consists of two pieces of FTO glass that is etched and prepared to become the electrodes for a string of solar cells. The cells have to be treated with titanium dioxide and then laced with silver traces, before being assembled with liquid electrolyte squirted in between. It’s finicky stuff, but the video almost makes it look easy… if you’re familiar with working in a chemistry lab, that is.

While it’s DIY-able, it’s at the outer edge of what some of us would be comfortable with. It does involve some steps with semi-obscure chemicals and the use of a kiln to produce the cells. The design shown here outputs around 5.8 volts and 51 milliamps. It’s not heaps, but it’s enough to run a low-power project for some time in an area with decent sun.

We’ve seen some other great solar projects over the years, too! Video after the break.

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Blast From The Past: Schematic Templates

February 27, 2024 by Al Williams 29 Comments

If you want to draw schematics today, you probably sit down at your computer. Why not? There are a ton of programs made to do the work easily, and the results look great. Back in the day, you might sit at a drafting table with a full set of T-squares, triangles, and maybe a Leroy. But what about when inspiration struck at the coffee shop (no, not a Starbucks in those days)? Well, you probably had a schematic drawing template. We were surprised you can still buy these at high prices. Or you can 3D print your own, thanks to [Jan Stech].

Templates of all kinds used to be very common. There were several for schematics, logic symbols, furniture, and even geometric shapes and curves. They were almost always green and transparent. A quick search on Amazon for “drafting template” shows you can still get the generic templates, but schematic ones are still expensive.

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Wireless Telescope Guidance You Can Build On The Cheap

February 27, 2024 by Lewin Day 1 Comment

Telescopes are fun to point around the sky, but they’re even better when you have some idea of what you’re actually looking at. Experienced sky-gazers love nothing more than whipping out some quality glassware and pointing it to the heavens to try and view some photons from some fancy celestial point of interest. To aid your own endeavors in this realm, you might consider following [aeropic’s] example in building a capable wireless telescope DSC.

Yes, [aeropic] built a capable digital setting circle (DSC) which can be used to quickly point a telescope at objects in the sky, with the aid of the right astronomical software. An ESP32 board runs the show, using AS5600 positional encoders on each axis of the telescope to understand the device’s orientation. The encoders are attached via 3D-printed components to track the motion of the telescope accurately. It can then be paired over Bluetooth with a smartphone running an app like Skysafari. Once calibrated on some known stars, the app can then read the encoder outputs from the telescope, and help guide the user to point the device at other stars in the night sky.

The rig won’t actually move the telescope for you, it just guides you towards what you want to look at. Even still, it makes finding points of interest much faster and could help you get a lot more out of your next sky viewing party. Have fun out there! Video after the break.

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Integration Taught Correctly

February 26, 2024 by Al Williams 31 Comments

[Math the World] claims that your calculus teacher taught you integration wrong. That’s assuming, of course, you learned integration at all, and if you haven’t forgotten it. The premise is that most people think of performing an integral as finding the area under a curve or as the “antiderivative.” However, fewer people think of integration as adding up many small parts. The video asserts that studies show that students who don’t understand the third definition have difficulty applying integration to real-world problems.

We aren’t sure that’s true. People who write software have probably looked at numerical integration like Simpson’s rule or the midpoint rule. That makes it pretty obvious that integration is summing up small bits of something. However, you usually learn that very early, so you’re forgiven if you didn’t get the significance of it at the time.

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The DeDeterminator Uses Quantum Physics To Make Decisions So You Don’t Have To

February 26, 2024 by Lewin Day 20 Comments

Are you making your own decisions and mainlining causality like a sucker? Why go through the agony, when you could hand over the railway switch of determinism to a machine that can decide things for you! Enter the DeDeterminator, a decision machine from [Oliver Child].

The construction is simple enough, being built inside a small tin. One kind of wishes it had a secret third “PERHAPS” bulb that illuminates only when the universe’s continued existence has been called into question.

The idea is simple. At the press of a button, the DeDeterminator illuminates a bulb—indicating either yes or no. The decision for which bulb to illuminate is truly random, as it’s determined by the radioactive decay of a Americium-241 alpha particle source. A Geiger-Muller tube is used to detect alpha particles, with the timing between detections used to determine the yes-or-no output of the device.

It’s a neat concept, and it’s kind of fun knowing that your decision is both out of your hands and as random as it could possibly be. Would the universe guide you wrong? Who could possibly question the reasoning of the particles? The only rational move could be to comply with whatever directive the box hath given. Just don’t ask it to make any decisions with dangerous outcomes.

We’ve featured other projects using radioactive decay for random number generation before, though they weren’t quite as philosophically intriguing as the DeDeterminator. Mostly they’re just about cryptographic security and such, but some do deal with causality in imaginary spaces, which has its own magic about it.

Meanwhile, if you’ve untangled the quantum chains of cause and effect, or you’ve just found a way to break RSA encryption using a Pi Pico, do drop us a line, won’t you?

TuneShroom Is An Artistic Mushroom-Themed MIDI Controller

February 25, 2024 by Lewin Day 1 Comment

Most MIDI controllers are modelled after traditional instruments, like pianos, flutes, or guitars. [Oliver Child] went in a different direction for the TuneShroom, instead modelling his DIY controller after the terrifying, unclassifiable living organism we call the mushroom.

The project was a fun way for [Oliver] to try creating a project with an artistic PCB design, and it worked out well in that regard. He penned a circuit board in the shape of a toadstool, with conductive pads serving as capacitive touch points to activate various notes.

The design is based around the Sparkfun Pro Micro, but it’s not programmed in Arduino. [Oliver] wanted to make full use of the ATmega32U4 microcontroller and have freedom to use the pins at will, so instead the project was programmed with a patched version of LUFA to handle the USB side of things. MIDI data is naturally piped out over this interface to an attached computer.

Files are on Github for the curious. Alternatively, contemplate turning an entire saxophone into a MIDI controller in your spare time. Video after the break.

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