work in progress

Based on:
http://code.google.com/p/4bitsynth/

Atmega48 / pwm: square, triangle, noise.

Aphex Twin in 4 bits / 4 channels:

What is the difference between MIC and LINE level?
Level refers to the relative strength of the signal and is measured in decibels. LINE level sources are much-amplified signals over MIC (microphone) level signals. Line level is usually between -10 to +4 dbm in strength while MIC levels are normally -60 dbm.

Line OUT signal voltage and impedance levels?
The line output “standard” designed to drive a load of 600 ohms or greater, at a mean signal level of 0.775V RMS. An exception exists in respect of compact disc players, where the output level is most commonly 2V RMS.

Preamplifier schematic
Thanks to Andy Collinson for sharing his circuit design.

How does it sound?
Electret microphone
Sensitivity: -35 to +4dB
Signal to noise ratio: 62dB
Recorded at 96000 hertz @ 24 bits

emc_kalimba.wav (right click and save)

My first electronic project (2005):

Download Eagle:
http://www.cadsoft.de/download.htm (Freeware)

Download all the libraries:

Download Sparkfun Eagle Library:
http://www.sparkfun.com/tutorial/SparkFunEagle-1-8-09.zip

Auto-route
Always change the Routing grid to 7 or so

Single side PCB (homemade)

since i don’t do PCB everyday…