[sdiy] Control Voltage Questions

[Grant Richter]

At 1 volt per octave a semitone is 83.3 millivolts.

An 8 bit DAC with 5 volt range has a resolution of 19.5 mv (5/256) per bit
or 78 mv per 4 bits. 83/78=1.064 so a slight amount of gain will allow you
to set each 4 bit step to be exactly a semitone. You may be able to adjust
the reference for the DAC to set it exactly with out a gain stage.

So 256/4=64 semitones/12=5.3 octaves. Plenty of range.

Have fun!


> From: "james" <djrage at gdi.net>
> Reply-To: owner-synth-diy at node12b53.a2000.nl
> Date: Sat, 3 Mar 2001 14:37:46 -0500
> To: <synth-diy at node12b53.a2000.nl>
> Subject: [sdiy] Control Voltage Questions
> 
> I've got a ciruit connected to my ISA bus that has a DAC on it which I have
> set up to output between 0-5V. Are there any precautions I should take
> before feeding this as CV into a synth?
> 
> How do I compute what note a givin voltage is with the V/Oct scaling?
> 
> Whats a way to make sure I get all voltages for all notes over 2,3 or 4
> octaves with the output of an 8bit DAC?
> 
> Thanks
> James
> 
>