Building An Ultrasonic Levitation Rig

February 2, 2021 by Lewin Day 12 Comments

Levitation may sound like magic, but there are a wide variety of physical phenomena that can be manipulated to generate the desired effect. In this case, [Mirko Pavleski] has built a rig capable of levitating small, lightweight particles through the use of ultrasound.

The rig uses a 60W ultrasonic transducer, operating at approximately 40 KHz, to generate a standing wave in combination with a reflector – essentially a rigid piece of material off which sound waves can be bounced. The interaction between the sound waves as they are emitted from the transducer and bounce off the reflector creates what is known as a standing wave, wherein there are areas of high and low amplitude that do not move in space. These areas correspond to the wavelength of the emission from the transducer, and allow lightweight pieces of styrofoam to be placed in to the low amplitude areas, where they are held in place by the wave.

It’s quite astounding the first time you see it in action, as the tiny particles appear to simply float in the air apropos of nothing. We’ve explored deeper applications of the technique before, too. Video after the break.

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Electronic Embroidery Birthday Card Is A Celebration Of Skills

February 1, 2021 by Kristina Panos 5 Comments

Hackers and makers can sometimes feel like they’re getting the short end of the stick when it comes to gift giving. You’re out there making thoughtful, intricate circuit sculptures, helpful software, or face masks for people, and what do you get in return? Okay, yes, usually gift cards or tools or other things that feed your creativity in the first place. But darn it, it would be nice to receive a handmade gift once in a while, right?

So here’s what you do: make friends with enough other makers that you find your birthday twin, or close enough that you both feel the warmth of the personal holiday you share. Then you get them to agree to trade handmade birthday presents with you. That’s more or less what happened between [Becky Stern] and [Estefannie], who seem to have found each other through the magic of sharing projects on YouTube.

[Becky]’s gift to [Estefannie] is a busy intersection of maker elements including graphic design, embroidery, electronics, and 3D printing. [Becky] started with the embroidery, which was made possible thanks to a new open-source library for Processing called PEmbroider. Once that was done, she 3D printed the frame and added the electronics — candle flicker LEDs for the birthday cake, and a handful of songs that are accessible via touch contacts screwed into the side of the frame. [Becky] added a real-time clock module so it plays a few extra songs on [Estefannie]’s actual birthday.

The most thoughtful element here is personalization, and it’s amazing what can happen when you put 100% of yourself into something that is 100% about someone else. Every bit of the art is personal to [Estefannie], and every atom of the build is pure [Becky]. Check out the demo and build video and see what [Estefannie] made for [Becky] after the break.

[Becky]’s varied creativity has graced these pages many times before. See how she bid adieu to 2020, built a daily affirmation mirror, and gave a mask-making masterclass in the early stages of the pandemic.

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Proofing Press Proves DIY Is A-OK

January 29, 2021 by Kristina Panos 17 Comments

Back in the day when most people read the news on wood pulp, newspaper outfits would run off a test print on a small proofing press. This gave them a chance to check for typos before printing off thousands of newspapers on the real press.

These presses can be used for more than letterpress proofing, as [Paul] proves with this DIY version (YouTube, embedded below). They are simple machines that use a heavy roller on bearings to provide uniform pressure, so they’ll work for lino-cut printmaking and aquatint etchings, too.

The roller is the most important bit and is easily the most expensive part of a build like this one. [Paul]’s was fashioned by a UK machinist that he found through ebay. The total cost was £220 (~$300 USD), which is well below the thousand-pound mark where commercial machine prices start.

[Paul] made the base and handle out of plywood and CNC’d the side panels out of aluminium. These side panels contain bearings that hold the roller’s ends in place. As the roller moves back and forth, it slides along on another set of bearings the underside of the press. These bearings ride thin metal rails on the underside of the press so they don’t wear grooves into the wood over time.

[Paul]’s press looks fantastic and looks like it does a great job with everything he throws at it. Some uses require raising up the surface to be printed on to get a good transfer, so [Paul] might make it adjustable in the z-direction at some point in the future. Check out the build and walk-through video after the break.

If [Paul] looks familiar, it’s because we featured his equally impressive large-format book press last spring.

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Apple Watch Gets Custom Transparent Case

January 27, 2021 by Lewin Day No comments

The Apple Watch was the tech company’s attempt to bring wrist computers into the mainstream. It’s naturally available in a variety of fits and finishes, but if you want something properly original, you’ve got to go custom. [Useless Mod] does just that with a clear case for the popular smartwatch.

The mod starts with a patient, careful disassembly of the watch – necessary given the delicate components inside. It’s achieved in the end with only having to drill out 1 screw and an unfortunately snapping of the crown wheel axle. However, [Useless Mod] presses on, and silicone casts the original Apple enclosure. The video goes over all the finer points, from degassing to using strips of acrylic plastic to act as runners. Once done, the silicone mold is used to produce a replica case in transparent epoxy, and the watch is reassembled.

The final result is impressive, with the case optically clear and showing off the watch’s internals. The look is improved by removing some of the original insulation tape to better reveal the PCBs inside. Unfortunately, the design of the watch, which is largely covered by a screen and heartbeat sensor, means it’s not the greatest choice for a clear case mod, but it works nonetheless. We’ve seen similar work before from [Useless Mod] too – like this transparent drone case for the Mavic Mini. Video after the break.

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Avoiding PCB Crosstalk

January 25, 2021 by Al Williams 13 Comments

Now that it is relatively cheap and easy to create a PCB, it is a common occurrence for them to be used in projects. However, there are a lot of subtleties to creating high-performance boards that don’t show up so much on your 555 LED blinker. [Robert Feranec] is well-versed in board layout and he recently highlighted an animation on signal crosstalk with [Eric Bogatin] from Teledyne LeCroy. If you want a good understanding of crosstalk and how to combat it, you’ll want to see [Eric’s] presentation in the video below.

Simplifying matters, the heart of the problem lies in running traces close together so that the magnetic fields from one intersect the other. The math is hairy, but [Eric] talks about simple ways to model the system which may not be exact, but will be close enough for practical designs.

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Buzzer Does Input And Output

January 25, 2021 by Al Williams 2 Comments

Piezo elements have the useful property of being bidirectional; that is they can move when you apply electricity to them, but they can also generate electricity when you move them. [Carl] takes advantage of this fact to make buttons that can provide haptic feedback. You can see a video of his efforts below the break.

He made two versions of the buttons. One uses a 3D printed housing and the other used a 3D printed spacer in a sandwich configuration. It took a few tries to get it right, as you’ll see. The elements take and produce relatively high voltages, so the bulk of the work was adapting the voltages back and forth. In fact, he even managed to fry his CPU chip with some of the higher voltages involved.

We’d probably look for an easier way to sense the button push, since it seems like a good bit of circuitry just to do that. But the whole circuit provides an input button, haptic feedback, and the option of using the buzzer as a buzzer, so at least it is relatively economical if you need all of those features.

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Lenticular Lens Makes Things Invisible

January 25, 2021 by Al Williams 7 Comments

Sure it is a cheap stage trick, but using a lenticular lens at the right angle and in front of the right background can render what’s behind it invisible. That’s not news, but [Ian] spent some time investigating how to make the best one he could. His instructions cover how to create your own with polycarbonate, the right lens, and some optically clear adhesive. You can see some details about the shield along with some demonstrations in the video below.

The first iteration of the design worked, but it had some distracting lines and curvatures. The second version uses a large sheet of polycarbonate and liquid adhesive to attach the lens. It looks much better.

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