We touched on harmonic table MIDI controllers when [aris] was building one. [Ken Rushton] has one of C-Thru’s commercial keypads, the AXiS-49, and disassembled the device to show how it works. A PIC18F2450 microcontroller provides the USB interface and is connected to a dsPIC33FJ128GP310 digital signal controller which decodes the keypresses. The membrane buttons are made with two concentric graphite disks that touch gold contacts. The microcontroller measures the time between the two points contacting to determine the button velocity. monome button clones also use circular contact pads, but cannot calculate velocity because they only have one element.

[via Matrixsynth]

Tinker.it has published plans for building a software synthesizer using an Arduino. The Auduino uses granular synthesis to create a truly unique sound. The grain is constructed from two triangle waves. Each one has adjustable frequency, decay rate, and the repetition rate can be changed too. The Arduino just needs five potentiometers attached to the analog inputs and an audio jack on the digital out. You don’t have to use pots; you can use anything that varies the analog input between 0 and 5 volts. A video of the device is embedded after the jump. Read the rest of this entry »

Matrixsynth pointed out a couple incredibly small optical theremins that look like they’d make for a great afternoon project. [AlexArt] first built the simple circuit on a piece of protoboard (Google translated). Knowing he could go smaller, he then built it freeform with a buzzer instead of a full size speaker. The design is based around the common 555 chip and photoresistor. Here’s a simple circuit you can use to lay out your own. The optical theremin should not be confused with the traditional RF theremin since the name comes from the similar sound, not similar construction.

Here’s another bit of analog synth pr0n for you: Initially sold in 1972, the EMS Synthi AKS was a portable modular analog synthesizer with a built in keyboard and sequencer. The VCS 3 portion of the device had a unique routing matrix pegboard used to connect components together. [firegroove] has opened up his precious machine so that you can see all of the fine little bits that make it tick… and chirp.

[via Matrixsynth]

Flickr user [firegroove] recently had to take apart his Roland TR-909 drum machine in order to fix it, and he photographed the entire teardown, offering detailed pictures of the TR-909’s internal parts. The TR-909 is legendary as one of the first fully programmable drum machines that could store entire songs, and its legend is only boosted by its scarcity: only 10,000 were ever made. If you can’t afford or simply refuse to tear yours apart, look after the break for a few more photos from inside.

Read the rest of this entry »