Who Needs Sea Monkeys? Get PlanktoScope

Plankton are tiny organisms that drift around in the ocean. They aren’t just whale food — they are responsible for fixing up to 50% of the world’s carbon dioxide. That, along with their position as the base of many important food chains, makes them interesting to science. Unfortunately, they are tiny and the ocean is huge. Enter Planktoscope. Billed as “an affordable modular quantitative imaging platform for citizen oceanography,” the device is a software-controlled microscope with the ability to deal with samples flowing through.

The software is in Python and uses existing libraries for user interface, image processing, and other tasks. The computing hardware is in the form of a Raspberry Pi. There are actually two prototypes of PlanktoScope available.

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Auto Xylophone Uses Homemade Solenoids

Want to play the xylophone but don’t want to learn how? [Rachad]’s automatic xylophone might be just the ticket. It uses homemade solenoids to play tunes under computer control. Think of it as a player piano but with electromagnetic strikers instead of piano keys. You can hear the instrument in action in the video below.

Since the project required 24 solenoids, [Rachad] decided to build custom ones using coils of wire and nails. We were amused to see a common curling iron used as an alternate way to apply hot glue when building the coils. The other interesting part of the project was the software. He now uses a toolchain to convert MIDI files into a serial output read by the Arduino. Eventually, he wants to train an AI to read sheet music, but that’s down the road, apparently.

Honestly, we were a bit surprised that it sounded pretty good because we understand that the material used to strike the xylophone and the exact position of the strike makes a difference. We doubt any orchestra will be building one of these, but it doesn’t sound bad to us.

The last one of these we saw did have more conventional strikers if you want to compare. Honestly, we might have just bought the solenoids off the shelf but, then again, we don’t make our own relays either.

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Blaupunkt Tube Radio Is The Sultan Of Radios

According to [M Caldeira], the Blaupunkt Sultan 24300 was one of the last tube radios made in the 1960s. He’s got one but it needed some tender loving care, and you can see how he approaches a restoration like this in the video below.

The radio was actually in better shape physically than most of the old radios we see. It wasn’t perfect, but it looked good on the outside. Electrically, though, it did need some work, and the dial had problems, too. The first obstacle was identifying exactly the model of the radio since there were a number of Sultan radios produced.

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Fluid Simulation Does The Math

If you like math, you should enjoy [kynd’s] page about simulating fluid in p5.js. You might still enjoy the pretty colors and shapes if you aren’t into math. What’s scary is that the page promises to have as little math as possible, but there’s still quite a bit. Of course, we are sure you could go even deeper down the rabbit hole.

The algorithm’s core is a pair of 2D arrays representing cells that comprise the display area. One array holds the color of the cell, while another holds a velocity vector of the fluid in the cell. A vector, of course, has both a magnitude and a direction.

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Hackaday Podcast 239: Overclocking, Oscilloscopes, And Oh No! SMD Out Of Stock!

Elliot Williams and Al Williams got together again to discuss the best of Hackaday for a week, and you’re invited. This week, the guys were into the Raspberry Pi 5, CNC soldering, signal processing, and plasma cutting. There are dangerous power supplies and a custom 11-bit CPU.

Of course, there are a few Halloween projects that would fit in perfectly with the upcoming Halloween contest (the deadline is the end of this month; you still have time). OpenSCAD is about to get a lot faster, and a $20 oscilloscope might not be a toy after all. They wrap up by talking about Tom Nardi’s latest hardware conversion of DIP parts to SMD and how TVs were made behind the Iron Curtain.

Did you miss a story? Check out the links below. As always, tell us what you think about this episode in the comments!

Go ahead and download it!

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An SMD Capacitor Guide

For electronics, your knowledge probably follows a bit of a bell curve over time. When you start out, you know nothing. But you eventually learn a lot. Then you learn enough to be comfortable, and most of us don’t learn as much about new things unless we just happen to need it. Take SMD components. If you are just starting out, you might not know how to find the positive lead of an SMD capacitor. However, if you’ve been doing electronics for a long time, you might not have learned all the nuances of SMD. [Mr SolderFix] has been addressing this with a series of videos covering the basics of different SMD components, and this installment covers capacitors.

If you are dyed-in-the-wool with SMD, you might not get a lot out of the video, but we picked up a few tips, like using a zip tie for applying flux. The video starts with an examination of the different packages and markings. Then it moves on to soldering the components down.

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Lessons Learned While Building A DIY Pen Plotter

There was a time when plotters were the pinnacle of computer graphics output. While they aren’t as common as they used to be, there are some advantages to having a plotter. [Symon] wanted a plotter and decided to make one from scratch. Truthfully, he wants to build a CNC machine, so the plotter is just a stepping stone. In fact, some of it may be a little much for just a plotter. Other design choices have worked for the plotter, but don’t look like they will work well for the eventual CNC design.

As an example, the plotter uses 2020 extrusions and lead screws. An Arduino with a CNC shield provides the brains. GRBL, of course, runs on the Arduino, so the whole machine runs fine with normal G-code. This post will be especially interesting if you want to build a plotter or something similar. We especially like that it covers the design rationale for each choice made It is great to learn from others successes and, of course, their mistakes.

If you really want just a plotter, you don’t have to spend much. You can even go super minimal if you want.