80's vintage Tomy Omnibot and Futaba RC Transmitter

80’s Omnibot Goes RC And Gets A Modern Refresh

August 22, 2021 by 5 Comments

Thrift stores, antique shops, knick-knack stores- Whatever you might call them in your locale, they’re usually full of “another man’s treasure”. More often than not, we leave empty-handed, hoping another shop has something we just can’t live without. But on rare occasions, when the bits all flip in our favor, we find real gems that although we have no idea what we’re going to do with them, just have to come home with us.

[Charles] ran into this exact situation recently when he walked into yet another shop among many dotting the highways and byways of Georgia and spotted it: A Tomy Omnibot beckoning to him from the 1980s. [Charles] didn’t know what he’d do with the Omnibot, but he had to have it. Not being one to have things just sit around, he set out to make it useful by combining it with an era-appropriate Futaba 4 channel AM radio, and updating all of the electronics with modern hardware.  The Mission? Drive it around at car shows and meetups where he already takes his 1980’s era vans.

We’re not going to spoil the goodies, but be sure to read [Charles]’ blog post to see how he hacked a modern 2.4 GHz 7 channel radio into the vintage Futaba 4 channel AM radio case. We appreciated his analytical approach to meshing the older gimbals and potentiometers with the new radio guts. Not to mention what it took to get the Omnibot back into service using parts from his battle bots bin. You’ll love the attention to detail on the new battery, too!

We’ve featured [Charles] work in the past, and his Power Wheels racer fed by a recovered Ford Fusion battery is simply unforgettable. You might also appreciate another Omnibot revival we featured recently. And as always, if you have a hack to share, submit it via the Tip Line!

Automated musical instrument with LED array

ESP32 Is The Brains Behind This Art Installation

August 22, 2021 by 10 Comments

The ESP32 has enabled an uncountable number of small electronics projects and even some commercial products, thanks to its small size, low price point, and wireless capabilities. Plenty of remote sensors, lighting setups, and even home automation projects now run on this small faithful chip. But being relegated to an electronics enclosure controlling a small electrical setup isn’t all that these tiny chips can do as [Eirik Brandal] shows us with this unique piece of audio and visual art.

The project is essentially a small, automated synthesizer that has a series of arrays programmed into it that correspond to various musical scales. Any of these can be selected for the instrument to play through. The notes of the scale are shuffled through with some random variations, allowing for a completely automated musical instrument. The musical generation is entirely analog as well, created by some oscillators, amplifiers, and other filtering and effects. The ESP32 also controls a lighting sculpture that illuminates a series of LEDs as the music plays.

The art installation itself creates quite haunting, mesmerizing tunes that are illustrated in the video linked after the break. While it’s not quite to the realm of artificial intelligence since it uses pre-programmed patterns with some randomness mixed in, it does give us hints of some other projects that have used AI in order to compose new music.

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Electromagnetic Interference For Fun And Profit

August 22, 2021 by 24 Comments

There was an urban legend back in the days of mechanical electricity meters, that there were “lucky” appliances that once plugged in would make the meter go backwards. It probably has its origin in the interaction between a strongly capacitive load and the inductance of the coils in the meter but remains largely apocryphal for the average home user. That’s not to say that a meter can’t be fooled into doing strange things though, as a team at the University of Twente have demonstrated by sending some more modern meters running backwards. How have they performed this miracle? Electromagnetic interference from a dimmer switch.

Reading the paper (PDF link) it becomes apparent that this behavior is the result of the dimmer switch having the ability to move the phase of the current pulse with respect to the voltage cycle. AC dimmers are old hat in 2021, but for those unfamiliar with their operation they work by switching themselves on only for a portion of the mains cycle. The cycle time is varied by the dimming control. Thus the time between the mains zero-crossing point and their turn-on point is equivalent to a phase shift of the current waveform. Since electricity meters depend heavily upon this phase relationship, their performance can be tuned. Perhaps European stores will now brace themselves for a run on dimmer switches.

If you’re curious about these old-style dimmers, take a look at some of their basic functionality.

Thanks [Dorus] for the tip.

Two-Part Primer In A Can Is A DIY Dream Come True

August 21, 2021 by 29 Comments

When putting together a home workshop, available floor space is often the deciding factor when it comes time to pick tools and equipment. This ultimately leads to some very difficult decisions, and we’d wager there isn’t a hacker or maker reading this that hasn’t had to pass on a new piece of gear because they didn’t have anywhere to put it.

For example, the average home gamer isn’t going to have a paint booth and spraying equipment, so they have to settle for a rattle can in the backyard. Traditionally this has limited the kinds of products you can realistically apply, but as [Eric Strebel] shows off in his latest video, it seems like spray can technology is starting to catch up.

3D printed part with two coats of spray primer applied
The finish after two coats of primer.

Specifically, he’s been working with a canned two-part primer that doesn’t require any complicated mixing or special equipment to apply. After hitting a plunger on the bottom, a small compartment containing the activator is ruptured and the reaction begins. From that point, you’ve only got 24 hours to use the contents of the can before it cures. But since you only need to wait about 10 minutes between coats, that should give you plenty of time to complete the project.

In the video, [Eric] demonstrates how quickly this high-build primer can smooth out the layer lines on a 3D print. While you’ll still need to sand and potentially break out the spot filler to achieve that perfect finish, it’s clear that the primer works much better than anything we’re used to seeing come out of a can. Even after just two coats, the results are truly remarkable.

If there’s a downside, it’s that a can of this primer will run you about $25 USD. That’s about five times the cost of the Rust-Oleum Filler Primer that usually gets recommended in DIY circles, but the results really do seem to speak for themselves. We wouldn’t necessarily use this on every project, but if you’ve got something that needs an especially fine finish, you’ve at least got an option that doesn’t involve borrowing somebody’s compressor and spray gun.

If you need help shaking your paint before spraying – definitely give this 3D printed paint shaker a look!

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Homemade electric fan showing a small camera peeking up above the central hub.

Keep Cool With This Face-Following Fan

August 21, 2021 by 8 Comments

[AchillesVM] decided to build a tabletop electric fan so it would track him as he moves around the room. Pan and tilt control is provided by a pair of servos controlled by a Raspberry Pi 3b+. How does it know where [AchillesVM} is? It captures the scene using a Raspberry Pi v2 Camera and uses OpenCV’s default face-tracking algorithm to find him. Well, strictly speaking, it tracks anyone’s face around the room. If multiple faces are detected, it follows the largest — which is usually the person closest to the fan.

The whole processing loop runs at 60 ms, so the speed of the servo mechanism is probably the limiting factor when it comes to following fast-moving house guests. At first glance it might look like an old fan from the 1920s, in fact [AchillesVM] built the whole thing by himself, 3D-printing case and using a few off-the-shelf parts (like the 25 cm R/C plane propeller).

It’s a work in progress, so follow his GitHub repository (above) for updates. Hopefully, there will be a front-mounted finger guard coming soon. If you like gadgets that interact with you as you move about, we’ve covered the face-tracking confectionery cannon back in 2014, and the head-tracking water blaster last year. In the “don’t try this” file goes the build that started a career — the eye-tracking laser robot.

Tiny ball magnets implanted in muscles could provide much better control over prosthetics.

Magnets Could Give Prosthetic Control A Leg Up

August 21, 2021 by 6 Comments

Today, prostheses and exoskeletons are controlled using electromyography. In other words, by recording the electrical activity in muscles as they contract. It’s neither intuitive nor human-like, and it really only shows the brain’s intent, not the reality of what the muscle is doing.

Researchers at MIT’s Media Lab have figured out a way to use magnets for much more precise control, and they’re calling it magnetomicrometry (MM). By implanting pairs of tiny ball magnets and tracking their movement with magnetic sensors, each muscle can be measured individually and far more accurately than with electromyography.

After embedding pairs of 3mm diameter ball magnets into the calves of turkeys, the researchers were able to detect muscle movement in three milliseconds, and to the precision of thirty-seven microns, which is about the width of a human hair. They hope to try MM on humans within the next couple of years. It would be a great solution overall if it works out, because compared with the electromyography method, MM is cheaper, less invasive, and potentially permanent. Couple MM with a new type of amputation surgery called AMI that provides a fuller range of motion, less pain overall, and finer control of prosthetics, and the future of prostheses and rehabilitation looks really exciting. Be sure to check out the video after the break.

There’s more than one way to control prostheses, such as deep learning and somatosensory stimulation.

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Modern Tape Echo Made Easy

August 21, 2021 by 11 Comments

Modern popular music increasingly relies on more and more complicated and intricate equipment and algorithms to generate catchy tunes, but even decades ago this was still the case. The only difference between then and now was that most of the equipment in the past was analog instead of digital. For example, the humble tape echo was originally made by running a loop of magnetic tape over a recording head and then immediately playing it back. Old analog machines from that era are getting harder and harder to find, so [Adam Paul] decided to make his own.

At first, [Adam] planned to use standard cassette tapes in various configurations in order to achieve the desired effect, but this proved to be too cumbersome and he eventually switched his design to using the cassette internals in a custom tape deck. The final design includes a small loop of tape inside of the enclosure with a motor driving a spindle. The tape is passed over a record head, then a read head, and then an erase head in order to achieve the echo sound. All of this is done from inside of the device itself, with 1/4″ jacks provided so that the musician can plug in their instrument of choice just like a standard effects pedal would be configured.

The entire build is designed to be buildable and repairable using readily-available parts as well, which solves the problem of maintaining (or even finding) parts from dedicated tape echo machines from decades ago. We like the sound from the analog device, as well as the fact that it’s still an analog device in a world of otherwise digital substitutes. Much like this magnetic tape-based synthesizer we featured about a year ago.

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