When it comes to guitar effects pedals, the industry looks both back and forward in time. Back to the 50’s and 60’s when vacuum tubes and germanium transistors started to define the sound of the modern guitar, and forward as the expense and rarity of parts from decades ago becomes too expensive, to digital reproductions and effects. Rarely does an effects company look back to the turn of the 19th century for its technological innovations, but Zvex Effects’ “Mad Scientist,” [Zachary Vex], did just that when he created the Candela Vibrophase.
At the heart of the Candela is the lowly tea light. Available for next to nothing in bags of a hundred at your local Scandinavian furniture store, the tea light powers the Zvex pedal in three ways: First, the light from the candle powers the circuit by way of solar cells, second, the heat from the candle powers a Stirling engine, a heat engine which powers a rotating disk. This disc has a pattern on it which, when rotated, modifies the amount of light that reaches the third part of the engine – photoelectric cells. These modulate the input signal to create the effects that give the pedal its name, vibrato and phase.
Controls on the engine adjust the amount of the each effect. At one end, the effect is full phasor, at the other, full vibrato. In between a blend of the two. A ball magnet on a pivot is used to control the speed of the rotating disk by slowing the Stirling engine’s flywheel as it is moved closer.
While more of a work of art than a practical guitar effect, if you happen to be part of a steam punk inspired band, this might be right up your alley. For more information on Stirling engines, take a look at this post. Also take a look at this horizontal Stirling engine.
Continue reading “A Candle Powered Guitar Pedal”
Let’s face it, everybody wants to build a Stirling engine. They’re refined, and generally awesome. They’re also a rather involved fabrication project which is why you don’t see a lot of them around.
This doesn’t remove all of the complexity, but by following this example 3D printing a Sterling engine is just about half possible. This one uses 3D printing for the frame, mounting brackets, and flywheel. That wheel gets most of its mass from a set of metal nuts placed around the wheel. This simple proof-of-concept using a candle is shown off in the video after the break, where it also gets an upgrade to an integrated butane flame.
Stirling engines operate on heat, making printed plastic parts a no-go for some aspects of the build. But the non-printed parts in this design are some of the simplest we’ve seen, comprising a glass syringe, a glass cylinder, and silicone tubing to connect them both. The push-pull of the cylinder and syringe are alternating movements caused by heat of air from a candle flame, and natural cooling of the air as it moves away via the tubing.
We’d say this one falls just above mid-way on the excellence scale of these engines (and that’s great considering how approachable it is). On the elite side of things, here’s a 16-cylinder work of art. The other end of the scale may not look as beautiful, but there’s nothing that puts a bigger smile on our faces than clever builds using nothing but junk.
Continue reading “When Stirling Engines Meet 3D Printers”
Following the time-honored YouTube tradition of ordering cheap stuff online and playing with it while the camera runs, [Monta Elkins] bought a Stirling engine that drives a DC motor used as a generator. How much electrical juice can this thing provide, running on just denatured alcohol? (Will it blend?)
The answer is probably not really a spoiler: it generates enough to run “Blink.ino” on a stock Arduino, at least when powered directly through the 5 V rail. [Monta] recorded an open-circuit voltage of around 5 V, and a short-circuit current of around 100 mA at a measured few hundred millivolts. While he didn’t log enough of the points in-between to make a real power curve, we’re guessing the generator might be a better match for 3.3 V electronics. The real question is whether or not it can handle the peaky demands of an ESP8266. Serious questions, indeed!
The video is a tad long, but it’s more than made up for by the sight of an open flame vibro-botting itself across his desk while [Monta] is trying to cool the cold side down with a melting ice cube. Which got us thinking, naturally. If you just had two of the Stirling engines… Continue reading “Ethanol-Powered Arduinos”
Stirling engines are really cool machines, invented by Reverend Dr. Robert Stirling in 1816 to rival the steam engine, they are one of the most efficient engines ever conceived. Building one is a very rewarding experience, but it has a certain level of difficulty. However, [Attila Blade]’s version of a free-piston type Stirling engine is simple enough to be built in a matter of minutes.
To build the engine you only need a test tube, steel wool, a latex glove, an O ring and some wire. The construction is straightforward as you can see in the video. The whole engine rocks on the wire frame which also makes it different to most other Stirling engines that you can watch on the net. The free piston is just one type of several possible configurations for a Stirling. The most common one, is the beta type, usually made with soda cans, but it is much more difficult to build than [Attila Blade]’s engine.
This is definitely a fun project that you may want to try, and is also a great way to learn thermodynamics concepts. Even if you don’t build this particular version, there are many other possibilities using mainly household items, or you can also check the very interesting history behind the Stirling engine.
Modern internal combustion engines have around 500 parts, with many of them moving in concert with the piston. But have you seen an engine with only one moving part, out of four in total? In the thermoacoustic engine, the power piston is the only part in motion. [YTEngineer] has built a very simple prototype that works on power provided by a tealight.
His little engine, slightly larger than a cigarette lighter, is composed of a test tube that serves as the cylinder, a smaller tube, called the choke, that fits inside the test tube, the stack, which is nothing more than some steel wool, and the power piston. [YTEnginer] nicely explains how the engine works: basically a temperature difference is used to induce high-amplitude sound waves that create the piston’s back-and-forth movement. The engine can be easily converted to an electricity generator by adding a magnet to the piston and a coil surrounding it.
The thermoacoustic engine is a particular type of Stirling engine. They have been proposed as electricity generators for space travel using radioisotopes as the heat source, among other applications. You may be interested in the history of Stirling engines, or perhaps even build a simple one.
Continue reading “Thermoacoustic Engine has Only One Moving Part”
In the early years of the nineteenth century, steam engines were at work in a variety of practical uses. However, they were still imperfect in many ways. One particular problem were the boilers, that had a tendency to explode, causing injuries and fatalities. Reverend Dr. Robert Stirling, a Scottish clergyman, was concerned about the death toll from exploding boilers. Based on previous work by George Cayley (known for his pioneering work on aeronautics), Stirling filed his patent for a safer engine in 1816. That makes this year the bicentenary of this engine. The Stirling engine has the highest theoretical efficiency of any thermal engine. It is also a relatively simple machine. Unlike other types of engines, there are no valves, and that makes the mechanical design much simpler.
Continue reading “200 Years of The Stirling Engine”
The sheer beauty of this build is blinding. We enjoy keeping a minimalistic household — not quite on the level of [Joe MacMillan] but getting there — yet this would be the thing we choose as decoration. It’s a hand-built 2-stroke Engine designed specifically to make the combustion process visible rather than locking it away inside of a block of metal.
If you have a nagging feeling you’ve seen this before it’s because the amazing craftsmanship is unforgettable. A couple years back we looked at the 4-stroke engine also built by [Huib Visser]. This new offering does away with the belt, leaving a build that is almost entirely glass and metal polished to a high sheen. The glass cylinder contains the combustion, pushing the graphite piston to drive the fly-wheel. A passing magnet triggers the spark plug to ignite the white-gas fuel, all of which is well-illustrated in the video after the break.
This is not for sale, which doesn’t surprise us. How hard would it be to part with something of such beauty especially knowing you created that beauty? But don’t worry, you can definitely build your own. Just make sure to set the bar lower for your first half dozen tries. We’ve even seen engine builds using hardware store parts.
Continue reading “2-Stroke Engine too Beautiful to Behold”