Easy Free Piston Stirling Engine

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.

 

Build Your Own High Power Air Cannon Out Of PVC

[NightHawkInLight] a.k.a. [Ben] recently built an awesome high power air cannon out of PVC pipe. PVC air cannons are great, and everyone should build one of these at some point in their life, but what really makes this build exceptional is the valve. [Ben] created a piston valve for this cannon that can be built with parts sourced from your local home supply store. Anyone can build this thing, and everyone should.

Instead of using a ball valve or other such contrivance to dump air directly from a reservoir into the chamber of this PVC air cannon, [Ben] is using a much more clever design. This is a barrel sealing PVC air cannon, with a moving piston sealed against a rubber hose clamp in the barrel. Adding air through the fill valve moves the piston forward, allowing air to leak into the reservoir. The air supply is then disconnected, and the trigger released causing the piston to move backward. This releases all the air in the reservoir into the barrel instantaneously, resulting in faster ping pong balls and potatoes.

The original trigger for this high power PVC air cannon used a simple ball valve for the trigger. [Ben] didn’t like this solution – it was hard to open and somewhat unergonomic. The ball valve trigger has since been replaced with a valve from a sprinkler system, giving this high power PVC air cannon a fancy brass trigger. It looks awesome, and can kill a watermelon from twenty yards. What more could you want in a high power PVC air cannon?

You can check out the videos for this build – including a guide for the clever piston valve – below.

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Star Trek Desktop Viewer In The Palm Of Your Hand!

There’s building small computers — like the Raspberry Pi — and then there’s building small computers — like this Desktop Viewer from Star Trek.

[Monta Elkins] is using a Beetle for this project; it’s an Arduino clone, hosting the ATMega32U4 microcontroller, with a unique feature that allows you to twist connecting wires to secure them to the board. Instead, [Elkins] went with the logical choice of soldering them. For a display, he used a SPI serial OLED 128 x 64 monochrome screen which he has cycling through a number of iconic Star Trek TOS symbols and animations. The images were converted into PROGMEM  — which gets loaded into flash memory — before finally being uploaded to the Beetle.

Following some fine 3D print work in ABS plastic which rendered the Desktop Viewer’s case, [Elkins] used acetone to solvent-weld the pieces together and applied a quick coat of paint to finish it off. This little replica would make a great desktop gadget as it requires a micro-USB to power the device.

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Popping the Top of A Ceramic IC

If you’ve ever wanted to open up an IC to see what’s inside it, you have a few options. The ceramic packages with a metal lid will succumb to a hobby knife. That’s easy. The common epoxy packages are harder, and usually require a mix of mechanical milling and the use of an acid (like fuming nitric, for example). [Robert Baruch] wanted to open a fully ceramic package so he used the “cooler” part of a MAP gas torch. If you like seeing things get hot in an open flame, you might enjoy the video below.

Spoiler alert: [Robert] found out the hard way that dropping the hot part isn’t a great idea. Also, we are not sure what the heat does if you want to do more than just inspect the die. It would be interesting to measure a junction on the die during the process to see how much heat actually goes to the device.

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Hackaday Prize Entry: WiFi In Wall Switches

The Internet of Things and Home Automation are the next big thing, even though we’ve had X10 switches and controllers for forty years. Why the sudden interest in home automation? Cheap microcontrollers with WiFi, ZigBee, and Z-wave, apparently. For this Hackaday Prize entry, [Knudt] is building a WiFi switch, meant to be retrofitted into any Euro wall switch.

There are three parts of [Knudt]’s WiFi wall switch, each of them with different requirements. The top layer is the switch itself and a small OLED display. These switches are really two small capacitive switches, which means there’s no reason to go through the work of sourcing a proper mechanical switch. Good thinking, there. The second layer of this contraption is basically an ESP8266, providing all the logic for this wall switch. The bottom layer is a bit more interesting, housing the 110-230V input, with a Triac or relay. This is where the fun, burny stuff happens.

Right now, you can go down to your local home supply store and simply buy a device like this. History has shown that’s a terrible idea. With home automation cloud services shutting down and security vulnerabilities abound, a DIY or Open Source home automation project really is the best idea. That makes [Knudt]’s project a great entry for the Hackaday Prize.

PlatformIO and Visual Studio Take over the World

In a recent post, I talked about using the “Blue Pill” STM32 module with the Arduino IDE. I’m not a big fan of the Arduino IDE, but I will admit it is simple to use which makes it good for simple things.

I’m not a big fan of integrated development environments (IDE), in general. I’ve used plenty of them, especially when they are tightly tied to the tool I’m trying to use at the time. But when I’m not doing anything special, I tend to just write my code in emacs. Thinking about it, I suppose I really don’t mind an IDE if it has tools that actually help me. But if it is just a text editor and launches a few commands, I can do that from emacs or another editor of my choice. The chances that your favorite IDE is going to have as much editing capability and customization as emacs are close to zero. Even if you don’t like emacs, why learn another editor if there isn’t a clear benefit in doing so?

There are ways, of course, to use other tools with the Arduino and other frameworks and I decided to start looking at them. After all, how hard can it be to build Arduino code? If you want to jump straight to the punch line, you can check out the video, below.

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Drinkable Clouds Get You Second-Hand Drunk

While the rise of electronic cigarettes and vaping has led to many aggravated bystanders, an installation in Germany may have found a vapor of a different ilk. Rather than nicotine, this cloud of vapors is full of tequila which precipitates out into glasses (or people) who happen to be nearby.

The cloud generator uses ultrasonic devices to vibrate the tequila molecules until they form a fine mist. The mist is delivered outward towards the sculpture, where a delicious cloud forms. From there, the cloud literally rains tequila out into its original, drinkable tequila form. It appears to take a while to gather enough tequila from the cloud, though, so there is a convenient tap on the side that will dispense it without all the rigmarole.

Basically this is a nebulizer which is using tequila and dispersing the output rather than directing it. You’re unlikely to get a large enough gasp for inebriation, but technically there is an opportunity a risk here of becoming second-hand drunk.

The installing is an effort by the Mexican Tourism Board to encourage Germans to take a break from the rain in favor of visiting sunny Mexico, we’d have to say that the effort seems to be a success. Once there, hopefully any visitors will be able to enjoy a perfect margarita or two as well.