Saturday, August 18, 2012

Present for "Obaachan"

My wife's grandma
celebrated her centennial, and i could not go, but wanted to express something as a synth to her.  The idea is to encode the relationship of grandma to great grandson as two wavelengths, λGrandma λKiri = 100/2.  So two oscillators spaced on the 50th harmonic.  That, in musical pitches is:
  1. choose a lowish, baritone note.
  2. the other note will be 3 octaves and an augmented fifth above.
So this pitch relationship of low to high is meant to instruct the baby on how much "time volume" grandma has really got, compared to his meager two years.
A note on attenuation: due to law of RMS, if the two waves had the same amplitude, the high one would be 50 times louder!  It needs to be attenuated.  Various ways include an rc filter on the speaker amplifier.  I chose to manually step the input resistors.  The high pitch is attenuated 50dB.  It was wrapped in white fur.

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