Year: 2018

A BCD Wristwatch You’d Want To Wear

July 24, 2018 by 4 Comments

Timepieces are a staple of Hackaday, we have featured so many of them over the years that for us to become really excited by a fresh one it must be particularly special. The days when simply breaking out the Nixies was enough are long past.

So this binary wristwatch project by [Sverd Industries] definitely caught our eye. Not for being particularly novel, after all binary LED clocks are not in themselves hard, but for the exceptionally high quality of its construction. It’s a simple enough design, with a real-time clock chip and an ATmega328 in its most power-sipping mode on a circular PCB with an array of LEDs as the display, and all contained within a 3D-printed shell.

This design has real quality, the discrete components are tucked underneath the board leaving the  ICs on the top with only the LEDs for company. The glass front is glued into place, and the shell is professionally 3D-printed. Power comes from a single CR2032, and to save battery life the LEDs are only activated by the press of a concealed button. We would wear this watch. For that matter, you would wear this watch. Take a look at the video below the break, and we’re sure you’ll agree. Looks like a few are even available over on Tindie.

This isn’t the first binary watch we’ve featured, so it’s tough to pick a comparison. This very low BoM example might lack some of the polish of the one presented here, but it has the same ability to catch our eye.

Continue reading “A BCD Wristwatch You’d Want To Wear” →

A Dramatic Demo Of AC Versus DC Switching

July 24, 2018 by 48 Comments

Switches seem to be the simplest of electrical components – just two pieces of metal that can be positioned to either touch each other or not. As such it would seem that it shouldn’t matter whether a switch is used for AC or DC. While that’s an easy and understandable assumption, it can also be a dangerous one, as this demo of AC and DC switching dramatically reveals.

Using a very simple test setup, consisting of an electric heater for a load, a variac to control the voltage, and a homemade switch, [John Ward] walks us through the details of what happens when those contacts get together. With low-voltage AC, the switch contacts exhibit very little arcing, and even with the voltage cranked up all the way, little more than a brief spark can be seen on either make or break. Then [John] built a simple DC supply with a big rectifier and a couple of capacitors to smooth things out and went through the same tests. Even at a low DC voltage, the arc across the switch contacts was dramatic, particularly upon break. With the voltage cranked up to the full 240-volts of the UK mains, [John]’s switch was essentially a miniature arc welder, with predictable results as the plastic holding the contacts melted. Don your welding helmet and check out the video below.

As dramatic as the demo is, it doesn’t mean we won’t ever be seeing DC in the home. It just means that a little extra engineering is needed to make sure that all the components are up to snuff.

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Sad Without A SID? This Comes Pretty Close

July 24, 2018 by 36 Comments

The MOS Technologies 6851, popularly known as the SID, is a legendary sound synthesiser integrated circuit from the early 1980s that is most famous for providing the Commodore 64 home computer with its ability to make noise. At the time it was significantly better than what could be found in competitor machines, making it a popular choice for today’s chiptune and demo scene artists.

There’s a snag for a modern-day SID-jockey though, the chip has been out of production for a quarter century and is thus in short supply. Emulation is a choice, but of little use for owners of original hardware so it’s fortunate that [Petros Kokotis] has produced a SID replacement using a Teensy 3.6.

The operation is simple enough, the Teensy provides all the requisite SID data lines via some level shifters for the host microcomputer, and uses [Frank Boesing]’s ReSID library to do the heavy lifting part of being a SID. You can download the code from a GitHub repository, and he’s posted a video we’ve put below the break showing a prototype in action with a real Commodore 64. The audio quality isn’t brilliant due to a phone camera recording from a very tinny speaker, but notwithstanding that it has the air of the real thing.

This isn’t the first SID we’ve seen here. How about a MIDI synth using one?

Continue reading “Sad Without A SID? This Comes Pretty Close” →

HOPE XII: Make Your Own Holograms

July 23, 2018 by 28 Comments

Prior to this weekend I had assumed making holograms to be beyond the average hacker’s reach, either in skill or treasure. I was proven wrong by a Club-Mate box full of electronics, and an acrylic jig perched atop an automotive inner tube. At the Hope Conference, Tommy Johnson was sharing his hacker holography in a workshop that let a few lucky attendees make their own holograms on site!

The technique used here depends on interference patterns rather than beam splitting. A diffused laser beam is projected through holographic film onto the subject of the hologram — say a bouquet of flowers like in the video below. Photons from that beam reflect from the bouquet and pass back through the film a second time. Since light is a form of electromagnetic radiation that travels as a wave, anywhere that two peaks (one from the beam the other from the reflected light) align on the film, exposure occurs. With just a 1/2 second exposure the film is ready to be developed, and if everything went right you have created a hologram.

Simple, right? In theory, at least. In practice Tommy’s been doing this for nearly 30 years and has picked up numerous tips along the way. Let’s take a look at the hardware he brought for the workshop.

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DIY solar panel vs. commercial solar panel

DIY Vs. Commercially Made Solar Panel

July 23, 2018 by 31 Comments

The price of commercially made solar panels on eBay is around $1 per watt and have been for a few years, but the price of individual solar cells are likewise at a low price per watt, around $0.48.  Looking at those prices, it’s tempting to say that it’d be cheaper to just buy the solar cells and put together your own panels. But is it? Simply adding up all the costs might seem like a good way to tell, but you’d need to make a panel to really see what works and what doesn’t.

Part US$ Euros €
solar cells 53 45
aluminum U-channel 20 17
plexiglass 43 37
adhesive 8 7
clear epoxy resin 40 34
Total $164 140€

And so [GreatScott] did just that, with his own side-by-side comparison. He made a 100-watt solar panel and mounted it on his roof beside his commercially produced 100-watt one and compared their output.

The cost of his DIY panel rose quickly. To make a somewhat comparable panel he needed to buy aluminum U-channels, clear epoxy resin, and more. Shown here is the breakdown of his costs.

His commercial 100 watt solar panel would cost him $103 today (87.90€). Compare that to his $164 DIY panel. Also, his DIY one likely won’t weather as well as the commercial one and may not handle high temperatures as well either. You can see the results of his testing in the video below, along with all his construction steps.

Another component open to DIYers in a solar system is the charge controller which takes the solar panel’s output and uses it to charge the battery, with added features like MPPT. Check out this DIY charge controller with MPPT and WiFi for data logging.

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Fail Of The Week: How Not To Make A 3D Scanner

July 23, 2018 by 12 Comments

Sometimes the best you can say about a project is, “Nice start.” That’s the case for this as-yet awful DIY 3D scanner, which can serve both as a launching point for further development and a lesson in what not to do.

Don’t get us wrong, we have plenty of respect for [bitluni] and for the fact that he posts his failures as well as his successes, like composite video and AM radio signals from an ESP32. He used an ESP8266 in this project, which actually uses two different sensors: an ultrasonic transducer, and a small time-of-flight laser chip. Each was mounted to a two-axis scanner built from hobby servos and 3D-printed parts. The pitch and yaw axes move the sensors through a hemisphere gathering data, but unfortunately, the Wemos D1 Mini lacks the RAM to render the complete point cloud from the raw points. That’s farmed out to a WebGL page. Initial results with the ultrasonic sensor were not great, and the TOF sensor left everything to be desired too. But [bitluni] stuck with it, and got a few results that at least make it look like he’s heading in the right direction.

We expect he’ll get this sorted out and come back with some better results, but in the meantime, we applaud his willingness to post this so that we can all benefit from his pain. He might want to check out the results from this polished and pricey LIDAR scanner for inspiration.

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Be A Fire Bender With The Power Of Magnets

July 23, 2018 by 26 Comments

More often than you think, scientific progress starts with a simple statement: “Huh, that’s funny…” That’s the sign that someone has noticed something peculiar, and that’s the raw fuel of science because it often takes the scientist down interesting rabbit holes that sometimes lead to insights into the way the world works.

[Ben Krasnow] ended up falling down one of those rabbit holes recently with his experiments with magnets and flames. It started with his look at the Zeeman effect, which is the observation that magnetic fields can influence the spectral lines of light emitted by certain sources. In a previous video, [Ben] showed that light from a sodium lamp could be dimmed by a powerful electromagnet. Some of his viewers took exception to his setup, which used an oxy-acetylene flame doped with sodium passing through the poles of the magnet; they thought the effect observed was a simple magnetohydrodynamic effect, and not the Zeeman effect he was supposed to be testing. That led to the experiments in the video below, which started with a candle flame being strongly deflected by the magnet. [Ben] methodically worked through the problem, eliminating variables by going so far as to blow soap bubbles of various gasses within the magnet’s poles to rule out the diamagnetism of oxygen as a cause of the phenomenon. He finally showed that even hot air by itself is deflected, using a simple light bulb and a FLIR camera. It’s good stuff, and well worth a watch.

Spoiler alert: [Ben] is still scratching his head about what’s going on, and we’re looking forward to his conclusions. This isn’t his first rabbit hole expedition, of course; his experiments with creating plasma with high-pressure water were fascinating, as were his DIY superconducting ceramics. Continue reading “Be A Fire Bender With The Power Of Magnets” →