Quick And Easy Arduino-powered Theremin

April 5, 2012 by Brian Benchoff 19 Comments

[Martin] sent in a great guide to a simple Arduino based theremin. It’s a very small build – just a single common IC and some passive components – and easy enough to build in an afternoon.

The theremin is based on a simple LC oscillator built around a 7400 quad NAND gate IC, a wire antenna, and a few caps and resistors. When a hand moves closer to the antenna, the frequency of the oscillator increases; when a hand moves away, the frequency decreases. On the software side, the oscillator is connected to the internal hardware counter of the Arduino. Every time there’s a change in the voltage output by the oscillator (all the time, varying slightly with the distance from a hand to the antenna), the counter increases by one. This counter is tallied up over 1/10th of a second, and the distance from the instrumentalist to the theremin can be determined. From there, it’s just outputting a frequency to a speaker.

All the code, schematics, and board layouts are available on [Martin]’s guide, and most of our readers probably have the parts to build this lying around their workbench. You can check out a video of [Martin]’s theremin in action on his guide.

Make Your RC Car Drive Itself With This Simple Brain Swap

April 4, 2012 by Mike Nathan 13 Comments

arduino-rc-conversion

If the kids have lost interest in that RC car or truck you bought them over the holidays, [Randy Sarafan] from Instructables has a few ideas that might help make the toys fun again, while teaching your kids a bit about electronics in the process. In his writeup, he shows how to swap out the brains of your run of the mill RC truck, enabling it to do far more than was originally intended. The procedure is pretty simple, and something that you can easily involve your kids in, if you’d like.

He uses an Arduino and a motor shield to keep the conversion simple, but this can be done with just about any capable microcontroller you might have on hand. [Randy] added a Parallax Ping sensor to the front of the truck enabling it to avoid objects as it drives itself, but since he cut out the truck’s original control board we’re assuming that there’s no way to override the truck’s actions at present.

[Randy] calls the conversion a “robot” though it seems like more of a semi-autonomous rover if you ask us. Regardless, revamping an old RC car is certainly far better than letting it collect dust on a shelf, or worse, tossing it out during spring cleaning.

Continue reading to see a short video of [Randy’s] RC truck in action.

[via HackedGadgets]

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Auto-locking Pet Door Ensures That Your Outdoor Kitty Obeys Its Curfew

April 4, 2012 by Mike Nathan 26 Comments

If you’ve got a pet that roams freely in and out of your house, you may find yourself wanting to more closely regulate how they come and go. [tareker] was looking to keep his cat indoors at night when dangerous animals might be lurking in the neighborhood, but he didn’t want it to become a hassle.

He already had locking pet door on hand, which he hacked to regulate the egress and ingress of his cat automatically. He installed a pair of reed switches to determine if the door had been opened outwards (cat leaving) or inwards (cat returning), keeping track of the state using an Arduino Nano. A servo motor attached to the door’s frame locks the door whenever it detects the cat is safely inside after nightfall.

While he also added an RGB LED to reflect the status of the door, he’s considering connecting it to the Internet so that he can control and check the door from wherever he might be at the moment.

DrummerBot Joins The Jam Session When Your Bandmates Are Busy

April 3, 2012 by Mike Nathan 10 Comments

drummerbot

It seems that more often than not, [Steffest] finds himself inspired to rock out on his guitar without a percussion section to back him up. Like any enterprising hacker/musician would be wont to do, he built a robotic drummer to join in when he got the urge to play.

His DrummerBot is driven using an Arduino, which is tasked with controlling the 8 servo motors that the bot has at its disposal. The bot’s drum set is composed of a variety of items from fan motors to pot lids and more. [Steffest] wanted the ability to produce the maximum variety of sounds possible, so most of the servo motors are driven in two directions allowing the bot to strike more than one item with each “arm”.

[Steffest] is a big fan of interfacing physical objects with a web interface, so he built a simple HTML based sequencer that allows him to program the robot from his phone. Once the sequencer is programmed, the DrummerBot can be launched into action with the simple press of a button.

[Steffest] says that the bot works pretty well, but the sound is a bit raw if you hear it live. A little Ableton Live post-processing goes a long way to smooth things out however, as you can see in the video below.

[Thanks, Wesley]

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Open Source Tracking System Gets A Kickstarter

April 2, 2012 by Mike Nathan 19 Comments

Many of the hacks featured here inspire others to build on the creator’s work, and on occasion the positive feedback brings the hack to market. Last year we told you about [Wayne’s] creation, a system aimed at tracking down would-be game console thieves. He received a bunch of requests to document the tracker in full, so he decided to revise his creation and release it as Open Source Hardware.

As you might remember, his original tracking device was powered by an Arduino, which monitored an accelerometer and GPS sensor, reporting coordinates and movements to his mobile phone on demand. He combined the disparate components together on a single board, and started a Kickstarter for the project.

Aside from his original purpose of tracking stolen goods, he lists off an array of other uses, such as tracking the driving habits of your newly licensed teen, geofencing objects in certain areas and more.

If an SMS controlled all-in-one tracking system is something you might be interested in, check out his Kickstarter, or take a look at the documentation and build one of your own.

Rain Barrel Irrigation System Keeps Your Plants Fed When You’re Too Busy

March 29, 2012 by Mike Nathan 53 Comments

sprinkler-controler

[Kyle Gabriel] moved into a house with a nice tract of land behind it, but due to his busy schedule he had yet to plant the garden he so desperately wanted. He worried that his hectic life and busy hours would lead to accidentally neglecting his garden, so he built a water collection and automated irrigation system to ensure that his plants never went without fresh water.

The system is fed by two large 55 gallon barrels that collect rain from his gutters. A 1/2 HP well pump is used to pressurize the collected water, which is then dispensed throughout his garden by a sprinkler. [Kyle’s] system is run from a small control box where an Arduino is used to control the pump’s schedule. At a predefined time, the Arduino turns the pump on, while monitoring the system for potential problems.

If the system starts running low on water, the Arduino triggers the valve on his spigot to open, keeping the water level above the pump inlet pipe. He also keeps an eye on pump’s outlet pressure, indefinitely disabling it before a blockage causes the pump to cycle repeatedly.

He says that the sprinkler system works quite well, and with his modular design, he can add all sorts of additional functionality in the future.

Collecting Radon Data In The Name Of Science And Safety

March 27, 2012 by Mike Nathan 32 Comments

radon-data-collector

When [Chris Nafis] built an addition onto his historical home he found that a Radon problem, previously mitigated with plenty of concrete, seemed to rear its ugly head yet again. He eventually resigned himself to installing a Radon fan and detector – the latter of which offered no way to store measurement data. He wanted to get a better feel for the short and long-term Radon measurements in his house, in hopes of finding some correlation between temperature, moisture levels, and the total amount of Radon emitted from the ground.

To do this, he disassembled a pair of Radon detectors located in different parts of his house, each of which he wired up to an Arduino. Using his oscilloscope to determine which PCB leads controlled the different LED segments on the displays, he quickly had the Arduinos scraping measurement data from the sensors. [Chris] figured the best way to keep track of his data was to do it online, so he interfaced the microcontrollers with Pachube, where he can easily analyze his historical readings.

An additional goal he set for himself is to trigger the Radon fan only when levels start rising in order to save a little on his electric bill. With his data logging operation in full swing, we think it should be a easy task to accomplish.