A Tin Can Phone, But With Magnets

February 29, 2020 by Brian McEvoy 17 Comments

The tin can phone is a staple of longitudinal wave demonstrations wherein a human voice vibrates the bottom of a soup can, and compression waves travel along a string to reproduce the speaker in another can at the other end. All the parts in this electrical demonstration are different, but the concept is the same.

Speakers are sound transducers that turn electrical impulses into air vibrations, but they generate electricity when their coil vibrates. Copper wires carry those impulses from one cup to another. We haven’t heard of anyone making a tin can phone amplifier, but the strictly passive route wasn’t working, so an op-amp does some messy boosting. The link and video demonstrate the parts and purposes inside these sound transducers in an approachable way. Each component is constructed in sequence so you can understand what is happening and make sense of the results.

Can someone make a tin can ~~amplifier~~ transformer? We’d like to see that. In another twist of dual-purpose electronics, did you know that LEDs can sense light?

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HDD-Driven Chime Clock Is Quite Striking

January 21, 2020 by Kristina Panos 20 Comments

It seems that the more hectic life gets, the harder it is to consciously slow down and enjoy the experience. There’s always another bill to worry about, and a new deadline around the corner. The last thing we need are ultra-precise digital clocks everywhere we look. When it’s time to relax, there’s more than enough room for a passive type of clock that gives the time on time’s terms.

[Scoops]’ beautiful chime-only clock seems perfect for its location — an intimate event space inside an old house in Taiwan. Having only a vague sense of passing time helps us relax responsibly at social events. There’s no need to pull out your phone or glance at your watch when notifications about the passage of time softly permeate the air.

Here’s how it works: a NodeMCU controls four hard drive actuators through a ULN2003. The actuators each have a small extension and a clapper fitted on the end, which strikes the aluminium tubes that make up the chimes. There’s a web interface where [Scoops] can set the chimes to sound as frequently or infrequently as desired, or schedule a quiet period during the overnight hours. In emergencies, the clock can also be muted directly with the push of a button.

Take a little time to check out the short videos after the break, because this thing does a mean Westminster Chimes. But don’t stay too long, because time is running out! You have until Friday, January 24th to enter our Tell Time Contest over on IO.

Time can be relaxing or suffocating, depending on the way you look at it. If it’s visual relaxation you need, watch this bubble clock and float away from reality for a while.

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Solenoid Engine Adds Three “Pistons”

October 28, 2019 by Bryan Cockfield 9 Comments

The earliest piston engines typically had only one cylinder, and at best, produced horsepower measured in single digits. But once you have a working engine, it’s a relatively short step to adding cylinders and increasing the power output. [Emiel] made a similar upgrade to one of his engines recently, upgrading it from one cylinder to four. But this isn’t an internal combustion engine, it gets its power from electric solenoids.

We featured his single-cylinder build about a month ago, and since then he’s been busy with this impressive upgrade. The new engine features four cylinders arranged in a V4 pattern. Of course, this greatly increases the mechanical complexity. To start, he had to machine a crankshaft to connect all four “pistons” to a shared output shaft. He also had to build a set of cams in order to time the firing of the cylinders properly, so they don’t work against one another.

The build is just as polished and impressive as the last, which is saying a lot. [Emiel] has a quality machine shop and built the entire motor from scratch, including winding the solenoids, machining the connecting rods and shafts, and building a very picturesque wooden base for the entire contraption to sit on. It’s definitely worth checking out.

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Build Your Own Solenoid Engine

September 25, 2019 by Bryan Cockfield 13 Comments

A solenoid engine is a curiosity of the electrical world. By all measures, using electricity to rotate something can be done almost any other way with greater efficiency and less hassle. But there’s just something riveting about watching a solenoid engine work. If you want to build one of your own and see for yourself, [Emiel] aka [The Practical Engineer] has a great how-to.

For this build though he used a few tools that some of us may not have on hand, such as a lathe and a drill press. The lathe was used to make the plastic spool to hold the wire, and also to help wind the wire onto the spool itself rather than doing it by hand. He also milled the wood mounts and metal bearings as well, and the quality of the work really shows through in the final product. The final touch is the transistor which controls power flow to the engine.

If you don’t have all of the machine tools [Emiel] used it’s not impossible to find substitute parts if you want to build your own. It’s an impressive display piece, or possibly even functional if you want your build to have a certain steampunk aesthetic (without the steam). You can even add more pistons to your build if you need extra power.

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Stunning 4-Cylinder Solenoid Motor Should Be A Hit With Subaru Fans

September 18, 2019 by Lewin Day 47 Comments

As far as electric propulsion is concerned, the vast majority of applications make use of some kind of rotational motor. Be it induction, universal, brushed or brushless, these are the most efficient ways we have to do mechanical work with electricity. There are other, arcane methods, though – ones which [Maker B] explores with this 4-cylinder solenoid engine.

The principle of the solenoid engine is simple. Cylinders are wound with coils to act as solenoids, with the piston acting as the armature. When the solenoid is energised, it pulls the piston into the cylinder. The solenoid is then de-energised, and the piston can return to its initial position. The piston is coupled to a crankshaft via a connecting rod, and a flywheel is used to help the motor run continually. These are also known as reciprocating electric motors.

[Maker B]’s build is a 4-cylinder design in a boxer configuration. Produced with basic hand-operated machine tools, the build process is one to watch. Aluminium and brass are carefully crafted into the various components of the motor, and parts are delicately assembled with small fasteners and plenty of retaining compound. Solenoid timing is via a series of microswitches, installed neatly in the base of the motor and actuated by the crankshaft.

While solenoid motors are inefficient, they’re quite something to watch in action. This one is no exception, with the motor spinning up to 1100 rpm when running at 7.2 volts. We’d love to see some data on the power output and efficiency too. It’s possible to build solenoid motors in different configurations, too – this radial build is particularly fun. Video after the break.

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Lead Former Makes LED Cubes A Little Easier To Build

August 25, 2019 by Dan Maloney 8 Comments

There’s no doubting the allure of a nicely crafted LED cube; likewise, there’s no doubting that they can be a tremendous pain to build. After all, the amount of work scales as the cube of the number of LEDs you want each side to have, and let’s face it – with LED cubes, the bigger, the better. What to do about all that tedious lead forming?

[TylerTimoJ]’s solution is a custom-designed lead-forming tool, and we have to say we’re mighty impressed by it. His LED cubes use discrete RGB LEDs, the kind with four leads, each suspended in space by soldering them to wires. For the neat appearance needed to make such a circuit sculpture work, the leads must be trimmed and bent at just the right angles, a tedious job indeed when done by hand. His tool has servo-controlled jaws that grip the leads, with solenoid-actuated lead formers coming in from below to bend each lead just the right amount. The lead former, along with its companion trimmer, obviously went through a lot of iterations before [TylerTimoJ] got everything right, but we’d say being able to process thousands of LEDs without all the tedium is probably worth the effort.

We’re looking forward to the huge LED cubes this tool will enable. Perhaps this CNC wire bender and an automated wire cutter would come in handy for the supporting wires?

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Itty Bitty MIDI Piano Sings With Solenoids

August 13, 2019 by Kristina Panos 9 Comments

Toy pianos are fun to plink around on for a minute, but their small keyboards and even smaller sound make them musically uninteresting pretty quickly. [Måns Jonasson] found a way to jazz up a two-octave toy piano almost beyond recognition. All it took was thirty solenoids, a few Arduinos, a MIDI shield, and a lot of time and patience.

This particular piano’s keys use lever action to strike thin steel tines. These tines are spaced just wide enough for tiny 5V solenoids to fit over them. Once [Måns] got a single solenoid striking away via MIDI input, he began designing 3D printed holders to affix them to the soundboard.

Everything worked with all thirty solenoids in place, but the wiring was a bird’s nest of spaghetti until he upgraded to motor driver shields. Then he designed a new bracket to hold eight solenoids at once, with a channel for each pair of wires. Every eight solenoids, there’s an Arduino and a motor shield.

The resulting junior player piano sounds like someone playing wind chimes like a xylophone, or a tiny Caribbean steel drum. Check out the build video after the break.

Hate the sound of toy pianos, but dig the convenient form factor? Turn one into a synth.

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