An Uno-powered Photocell Piano

A Maker by the name of Asahillis has designed a Photocell Piano powered by an Atmel-based (ATmega328) Arduino Uno. Originally posted to Instructables, the DIY 6-note musical command center was recently featured on the HackADay website.

“When the user runs their hand over the top of the keys (photoresistors) they turn on audio notes, which can be tuned with potentiometers,” Asahillis explained. “This project utilizes [an Atmel-based] Arduino to turn the notes on and off. The tutorial includes a parts list, schematics and the code required to operate this musical device.”

According to HackADay’s Kristina Panos, the hack uses two circuits: one to generate the tones  and a second to mix them. Essentially, Asahillis adapted Forest Mims III’s schematics for the 555 Tone Maker and the 741 Audio Mixer to create the Photocell Piano.

“When the instrument is powered on, the code takes a 5-second reading of the ambient light, and sets a threshold based on its findings,” Panos explained. “Afterward, the first note will sound, indicating the piano is ready to be played. Each note has its own if-else statement that tells it to sound when its corresponding photoresistor reaches a value below the set threshold (when the player casts a shadow).”

Interested in learning more the Arduino-powered Photocell Piano? You can check out the original Instructables post here.

Building a DIY hearing aid with Arduino

A Maker by the name of “Ojoshi” has designed a DIY intelligent hearing aid prototype powered by an Atmel-based Arduino Mega (ATmega1280). The project, originally posted to Instructables, was recently featured on the HackADay website.

So, just how does the DIY hearing aid prototype work?

First, the platform employs an electret to capture audio, subsequently running it through a pre-amplifier to increase the gain 100x. The next stage consists of four filters – neatly dividing the input signal by frequency into four parts, which are passed into four LTC6910 programmable gain amplifiers, allowing the Arduino to control the gain of each channel. The LTC6910 then takes three digital inputs used to set the gain value.

“To determine which gain to use for each frequency band, the Arduino needs to know how much power is in each band,” explained HackADay’s Eric Evenchick. “An envelope detector averages the signal, which can be read by an analog input on the Arduino. Using this information, the hearing aid can boost specific frequencies when it detects conversation.”

As Evenchick notes, this hearing aid won’t quite fit in your ear, although there is quite a lot of interesting signal processing/action happening on the prototype.

Interested in learning more about Ojoshi’s DIY hearing aid prototype? You can check out the project’s official Instructables page here.

Plugduino = 120 volts of fun

The Plugdino can best be described as a platform that allows an Atmel based Arduino to control real-world 120 Volt electrical appliances.

The device can also be used as Halloween/horror prop controller to automate fog machines, laser and fans. More specifically, the platform supports beam breaks, contact pads and distance sensors – with users controlling up to four devices independently or in unison.

“You can use [Plugdino] in the house to control appliances based on sensors such as temperature, humidity, motion, light, and so on to open curtains, turn on lights, fans based on environmental conditions,” Instructables member Flashular explained in a recent post.

“You can also use it for more whimsical things like sign marquees, animated Christmas light lights, super sized Simon game and anything that takes input, runs program logic and controls 120V devices.”

According to Flashular, Plugduino can be thought of as a smart relay controller, which means users are able to write sketches to determines how each of the four electrical outlets are turned on or off – all while supplying up to 4 inputs to interface with the outside world.

“As a simple example, you can make a sequencer for the lights with a speed control simply by connecting a potentiometer to one of the inputs and using its value to control the sequencing speed,” Flashular added.

Key Plugdino specs include:

Power Circuit

• 1x 1″ x 1/4″ fuse holder
• 1x SPDT power switch
• 1x 1″x x1/4″ fast acting 7A 205V fuse
• 1x 4 position dual row terminal block
• 1x 16/3 120VAC extension cord
• 1x 2 gang outlet wall plate
• 2x 120VAC 15A duplex grounded outlet
• 1x dual gang outlet wall box extender

Control Circuit

• 1x Arduino Uno (ATmega328)
• 1x SeedStudio Relay Shield V2.0
• 4x 40mA 5mm white (or preferred color) LED
• 4x 40 mA green (or preferred color) LED
• 8x 220 ohm 1/4 watt resistors
• 4x 3-pole terminal block
• 1x 36 pin single row pin header

Interested in learning more about Plugdino? You should check out the project’s official page here.

Video: Building a multitouch music controller

Amanda Ghassaei – creator of the Glitchbox and Vocal Effect Box – recently published a detailed list of build instructions for an Atmel-based (Duemilanova or Uno), Arduino-powered infrared touchscreen/coffee-table interface.

According to Zoe Romano of the official Arduino blog, Ghassaei has been using the multitouch platform to control various music and graphics applications on her PC.

So, how does the platform work?

“The touchscreen uses infrared (IR) sensing to detect fingers and other objects on the screen, [while] an IR laser at each corner shines IR light across the surface of the screen,” Ghassaei explained.

“When a finger or other object touches the surface, it causes the IR light to scatter in many directions. Some of this light is directed down into the screen, towards an array of 64 IR sensors. By scanning through the sensors, you can determine the x and y position of the touch event(s) and use this to control a variety of apps.”

Interested in learning more about the Arduino-powered multitouch music controller? You can check out the project’s Instructables page here.

Printing a 3D Tardis-Transformer

Earlier this month, we gave props to a remarkably realistic DIY PIP-Boy (Personal Information Processor-Boy) made with a 3D printer. Today we’re taking a closer look at a Tardis Transformer which was designed using an open source RepRap 3D printer.

“I originally only had Soundwave in mind when I was designing this. So all the small details are based around his robot design. But I was catching heck for making the Tardis into a Decepticon so I repainted him and added a second head option to make him Vector Prime,” a Maker by the name of “Nonnef” explained in an Instructables post.

“I still think Soundwave would make an awesome Tardis, but anyone making this has their option of which to build. The print is still rough and needs cleaned up, but I keep changing the design faster than I keep up with actually printing him out. Going to keep it at a weekly print of what I currently have changed.”

As Hack A Day’s Brian Benchoff notes, be prepared for a very long print if you plan on having a go at the Tardis Transfomer, as the latest iteration of the model took approximately 30 hours with a .35 mm nozzle.

Nevertheless, the level of detail is impressive, as is the fact that 99% of the Tardis Transformer originated from a 3D printer – with only a pen spring and small screw scrounged elsewhere.

Additional information about the Tardis Transformer can be found here on Instructables, while details about Atmel-powered  RepRap 3D printers can be found here.

Building an Arduino-powered Nerf Vulcan sentry gun

BrittLiv – a chemical and biological engineering student – has transformed a Nerf Vulcan into a sentry gun capable of automatically aiming and firing at targets.

The azimuth and elevation mount for the gun is constructed out of plywood – with each axis controlled by a single servo attached to an Arduino Uno powered by Atmel’s stalwart ATmega328 MCU.

As the Hack A Day crew notes, the talented Maker also increased the voltage flowing to the gun’s motor, as well as the overall strength of the Vulcan by replacing a 2kg spring with a 5kg spring.

Meanwhile, targets are tracked with a webcam via Processing and some code from Project Sentry Gun. Of course, individuals wearing an Instructables t-shirt will be spared the otherwise inevitable barrage of plastic darts.

Additional key specs include:

• Servo for the turn axis: BMS-660DMG+HS
• Servo for the tilt axis: Hitec HS-805BB
• Wire
• TIP120 transistor
• 1N4004 diode
• 1k resistor
• Pin header
• 6 Volt battery pack
• 5 kg replacement spring for the Vulcan
• Optional: Paint and plastic primer for the gun
• 3 mm lead pearls or something similar as a counter weight
• 6V 3700mAh battery pack
• 9.6V 2000mAh battery pack
• Webcam
• Laptop

You can learn more about BrittLiv’s Arduino-powered Nerf Vulcan sentry gun on Instructables here.

A xylophone-playing robot?!

Makeblock is an aluminum extrusion construction system for DIY mechanics and electronics that can be used to create robots, toys, machines and even art-ware.

Recently, the folks at Makeblock constructed a “Music Robot” to showcase the versatility of its kit, using an Arduino Uno (powered by Atmel’s ATmega328), timing belt, sliding rail, step motor, electromagnet and motor driver.

“So far, the robot can be controlled by [an] application via USB cable installed on [a] computer, [or] by [a] smartphone [using] Bluetooth,” a Makeblock rep wrote in an Instructables blog post. “The special application for Android [devices] is in [the] planning [stage].”

Makeblock – which was recently covered by Makezine – is a startup located in Shenzhen, China.

Additional information about Makeblock’s xylophone-playing robot can be found here on Instructables and here on the official Makeblock forum.