Make Your Own Solenoids, Then Play The Xylophone

December 2, 2010 by Mike Szczys 25 Comments

Learn to manufacture your own solenoids and then use them to play the xylophone by watching the tutorial video after the break. [Humberto Evans] and the team at Nerd Kits do a great job of not only manufacturing the coils, but the xylophone itself. The bars are machined from some aluminum stock and they take you down the rabbit hole with they why’s and how’s of engineering the keys.

We’re unlikely to replicate this machining process but the solenoids are another story all together. Starting at about 3:30 you can learn about designing, building, and using these little marvels. They’re basically an electromagnetic cuff with a metal slug in the middle. The solenoid seen above uses a body milled from HDPE and wrapped with magnet wire. The slug in the center is steel, with a few rare-earth magnets at the top. When you run current through the coil it repulses the magnets on the slug, witch then strikes the xylophone key. Using a MOSFET and a protection diode, actuating them is as simple as sending a digital high from your microcontroller of choice.

We’ve seen solenoids used to play a vibrophone before, but those were commercial units. Making your own hardware is far more hardcore.

Continue reading “Make Your Own Solenoids, Then Play The Xylophone” →

Build A Confetti Cannon For Your Next Party

November 8, 2010 by Mike Szczys 11 Comments

[Scott] built a confetti canon to spice up the party. It’s pneumatic and re-purposes a fire extinguisher as the air tank. He had a refillable extinguisher that used water instead of chemical retardant. After emptying the water and ensuring all of the pressure had been release he swapped the hose and nozzle for a sprinkler solenoid valve. Securing the extinguisher’s actuator lever with a pipe clamp holds the internal valve open, leaving the solenoid to control the pressure release. This way the canon can be fired electronically, or manually.

This type of solenoid valve is a popular choice with pneumatic canons. We suppose you could even adapt this for use as a T-shirt cannon.

[Thanks BoBeR182]

Typewriter As I/O; Lets You Play Zork

November 1, 2010 by Mike Szczys 26 Comments

Okay, for many the fact that this typewriter plays Zork on paper instead of a CRT is the fascinating part of this hack. But we love the implementation that makes the keys of the device an input and output.

The electric typewriter has been fitted with a solenoid for each key (wow, that’s a lot of work). In the image above you can see they are housed on plywood platforms behind the typewriter and connect using a piece of mono-filament fishing line. This flexible connection means the solenoids have no adverse effect when you want to do the typing instead of the Arduino which drives the solenoids. [Johnathan M. Guberman] took advantage of this, adding a resistor for each key. When depressed the key completes a circuit with the resistor, acting as the input. In this way, you can play Zork with a piece of paper as the monitor, typing for the input, and watching the typewriter magically pound out responses. See it happen after the break.

Continue reading “Typewriter As I/O; Lets You Play Zork” →

Web Controlled Sprinkler Automation

September 16, 2010 by Mike Szczys 19 Comments

[Doug] needed to update his watering system to comply with his city’s new water saving ordinance. The old system wasn’t capable of being programmed to water only on even or odd calendar days. Rather than purchase a replacement he decided to build his own sprinkler controller. It needed to switch 12V solenoids, a job that’s not too hard to design for. Rather than re-invent the wheel, he modified a previous controller design. It is basically an Arduino and Ethernet shield on a his own etched board. In addition to the ATmega328 and an ENC28J60 (for ethernet connectivity) there is a bank of transistors to drive the watering solenoids. Now he has a web interface that controls the watering schedule and is fully in compliance with the new city code.

If you need another way to save when watering your grass you should take a look at the sidewalk-avoiding sprinkler.

Replacing The Driver Board In An Old-school Door Chime

September 1, 2010 by Mike Szczys 33 Comments

[Dan Kouba’s] parents replaced their doorbell button with one that lights up and found that the chime wouldn’t stop sounding after the button was pushed. These lighted buttons use an incandescent bulb in parallel with the button (a piece of hardware we’ve hacked in the past). It draws a small amount of current which isn’t enough to trigger the chime, but it is just enough that the chime unit reacts as if the button press never stopped. His parents asked what he could do about this and after some investigation he build a replacement board for the chime unit based around an ATtiny26L. The board monitors the voltage drop across a resistor in the doorbell circuit. When the comparator on the AVR detects a rise in the voltage drop across the resistor it rings the chimes, actuating the solenoids with a set of PNP transistors. [Dan] sent us all of the details which you can check out after the break.

Continue reading “Replacing The Driver Board In An Old-school Door Chime” →

IPhone Drum Machine Isn’t Synthesized

August 27, 2010 by Mike Szczys 11 Comments

There was a time when a drummer would grab some sticks and lay out a groove using the items around him as instruments. [Lsa Wilson] would rather not work quite that hard and has chosen to do the same thing by tapping on an iPhone screen. As you can see in the clip after the break, many of the items in the room around him have been fitted with solenoids. Each is connected to an Arduino which is then controlled by Open Sound Control and interfaced with the iPhone via TouchOSC. We love the sounds being created and can’t help being reminded of the Multixylophoniomnibus.

Holy Robin Trap Batman!

June 30, 2010 by Jakob Griffith 24 Comments

[Matt Meerian] introduced us to his kludge of cardboard, tape, mirrors, and electronics in the form of a clever non lethal robin trap. Whenever a pesky robin would enter the box, a sensor is triggered, the solenoid drops a lid, and the bird is contained (and we assume taken far away after that).

Of course the plan backfired; we wont spoil what happened, but you can click the link above to find out.

Related: Arduino Mouse Trap