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Published on: October 22, 2013 / Comments: 2

The Happy Birthday Box

Everyone usually agrees that home made gifts are usually more heart felt.  So instead of buying a gift,  Christian decided to make one for a friend.  Not too far from a musical birthday card, the Birthday Box, will present a message to the receiver on an LCD screen, and sing the song happy birthday.

The Happy Birthday Box uses a piezo buzzer for a speaker generated by an Arduino.  The text message is displayed on a standard 16×2 LCD screen, and powered by a battery pack.  There is a small roller switch as well, I assume everything turns on / off when you open and close the box but it wasn’t specifically stated as the functionality.

Keep this project bookmarked, and add a few LEDs for that valentine of yours.

Check out a quick video after the break;  Source code and more pictures on Christian’s blog.


Published on: October 6, 2013 / Comments: None

HardDJ Arduino based MIDI controller uses hard drives as jog wheels

Stumbled on this awesome project that uses 2 old hard drives platters as rotary encoders / jog wheels.  Obviously for the purpose of DJing!  I love it when people reuse hardware that was originally intended for another purpose.

The build uses an Arduino Mega 2560 as its main processor.  RGB LED’s for the VUmeters, some slider pots for fading, and some extra buttons and knobs for MIDI events.  On the PC software side, the author is using mixxx for the MIDI mapping.


Check out the video after the break.  More pictures in the gallery.  Source code here on GitHub. More documentation here.


Published on: September 26, 2013 / Comments: None

Building a noise generator with transistors

Believe it or not, it’s actually quite difficult to generate random numbers on computers and microcontrollers.  I’m talking about true random.  A lot of the randomness computers use isn’t random at all, it’s predictive (or pseudo random).  Difficult, but still predictive.   It’s important when doing cryptographic functions to use a good random source.

So f4grx decided to build a random circuit and do some analysis on it.  The circuit design is built around the idea of using an open collector on a transistor.  What’s essentially going to happen is tiny electrical noise in the air is going to cause the circuit to produce 1′s and 0′s which then can be used to plot random.

Interesting read.  Check out f4grx’s experience.

Published on: September 22, 2013 / Comments: None

Attiny 2313 V-USB Media Volume Control

I know this awesome project is a few weeks old but I’m going to use the fact that Rupert recently posted an update as my excuse to share it on hackalizer. As the title implies the V-USB Media Volume Control project is using V-USB. V-USB is software which makes it possible to add low-speed USB to almost any AVR microcontroller without any additional hardware.

Inside Volume Control EnclosureFrom selecting the perfect rotary encoder to designing and etching his own PCB and eventually making a custom enclosure, this project shows is all. Rupert explains some of the minor but important differences of the rotary encoder such as the number of detents and amount of force required to turn the knob and press the button.  He also shares an important lesson on load capacitance with regards to the crystal on his home-brew board. Check out the build video after the break.


Published on: September 17, 2013 / Comments: None

Build an Op-amp based RIAA phono preamp

Believe it or not some people are still in to vinyl, actually I think more people are getting into vinyl nowadays!  One thing you might not have on that fancy turbo pandora playing surround sound is a phono input for that crusty record player of yours.  Why not build a preamp so you can hook it up?

The build is based on an OPA2134 op-amp and uses a bipolar +12/-12 power supply.  Since this type of amplifier is high gain it is important to make good design decisions to reduce noise.   First off you should have an earth ground, and a fully shielded metal enclosure or else you might be picking up a lot of unwanted noise.  Second the power components should have ample space away from the audio components.  The rest can be handled with some resistors and caps.

Nice build.  Schematic included, check out the project on diyaudioprojects.

Published on: September 16, 2013 / Comments: None

LightBox – A Video Jockey oriented RGB LED controller

Bocho came up with a really neat controller for RGB LED strips.  The idea is to compliment a VJ performance, full of knobs and sliders of course.  Something that you can tweak in real time, but can also be assisted by the music.  Bocho started out with this post on bass detection on Arduino, which was then rolled into the controller.

The build uses 3 high power transistors for controlling current, and various pots and sliders that control oscillation speed, luminosity, hue, and selecting manual or beat detection all controlled by an Arduino.  Even better the project is wrapped in a decent looking enclosure.

Source code is available here. Full writeup here on bocho’s blog.  Enjoy a video demonstration after the break. (more…)

Published on: September 14, 2013 / Comments: 1

Arduino Guitar Tuner (Frequency Detector)

Here’s a project which rocks! nikoala3 made an Arduino Guitar Tuner based off of this Audino Frequency Detection project. Both projects are well documented so you just may learn something.

In her build nikoala3 shows you how you can take an AC signal and offset it using a voltage divider to bring it into the 0-5V range that the Arduinos Analog to Digital Convert (ADC) uses. The Arduino has a 10bit resolution but the project only uses the high 8 bits giving you a range of 0-255 counts.  The sketch detects the frequency at which the signal crosses a given threshold. Different strings produce different amplitudes so you have to tweak the threshold to where it works with all the strings on your guitar.

A few LEDs and one cool enclosure with a laser cut top really made this project pop. There is something really refreshing about finding well documented builds like this. Check out more build photos after the break.