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 No comments

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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MovieCart Plays Videos On The Atari 2600

February 23, 2024 by Lewin Day 12 Comments

The original Xbox and PlayStation 2 both let you watch DVD movies in addition to playing games. Seldom few consoles before or since offered much in the way of media, least of all the Atari 2600, which was too weedy to even imagine such feats. And yet, as covered by TechEBlog, [Lodef Mode] built a cartridge that lets it play video.

It’s pretty poor quality video, but it is video! The MovieCart, as it is known, is able to play footage at 80×192 resolution, with a color palette limited by the capabilities of the Atari 2600 hardware. It’s not some sneaky video pass-through, either—the Atari really is processing the frames.

To play a video using the MovieCart, you first have to prepare it using a special utility that converts video into the right format for the cart. The generated video file is then loaded on a microSD card which is then inserted into the MovieCart. All you then have to do is put the MovieCart into the Atari’s cartridge slot and boot it up. Sound is present too, in a pleasingly lo-fi quality. Control of picture brightness and sound volume is via joystick. You could genuinely watch a movie this way if you really wanted to. I’d put on House of Gucci.

Thanks to the prodigious storage available on microSD cards, you can actually play a whole feature length movie on the hardware this way. You can order a MovieCart of your very own from Tindie, and it even comes with a public domain copy of Night of the Living Dead preloaded on a microSD card.

We don’t see a big market for Atari 2600 movies, but it’s neat to see it done. Somehow it reminds us of the hacked HitClips carts from a while ago. Video after the break.

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No Inductors Needed For This Simple, Clean Twin-Tee Oscillator

February 18, 2024 by Dan Maloney 11 Comments

If there’s one thing that amateur radio operators are passionate about, it’s the search for the perfect sine wave. Oscillators without any harmonics are an important part of spectrum hygiene, and while building a perfect oscillator with no distortion is a practical impossibility, this twin-tee audio frequency oscillator gets pretty close.

As [Alan Wolke (W2AEW)] explains, a twin-tee oscillator is quite simple in concept, and pretty simple to build too. It uses a twin-tee filter, which is just a low-pass RC filter in parallel with a high-pass RC filter. No inductors are required, which helps with low-frequency designs like this, which would call for bulky coils. His component value selections form an impressively sharp 1.6-kHz notch filter about 40 dB deep. He then plugs the notch filter into the feedback loop of an MCP6002 op-amp, which creates a high-impedance path at anything other than the notch filter frequency. The resulting sine wave is a thing of beauty, showing very little distortion on an FFT plot. Even on the total harmonic distortion meter, the oscillator performs, with a THD of only 0.125%.

This video is part of [Alan]’s “Circuit Fun” series, which we’ve really been enjoying. The way he breaks complex topics into simple steps that are easy to understand and then strings them all together has been quite valuable. We’ve covered tons of his stuff, everything from the basics of diodes to time-domain reflectometry.

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