[sdiy] MS-20 tempco (was Model D service)

[Gordonjcp]

On Tue, May 09, 2017 at 06:18:18AM -0400, Tony Kalomiris wrote:
> With a ladder resistor string of 427 and 403 ohms resistors (ratio is 12th root of 2).
> Crude ascii cct below. I am not quite done analyzing this one. 
> 
> 
> |              |
> -- 427---*---403 ---* 
>                |
>               61.9 K
>                |
>               gnd
> 
> On 2017-05-09, at 3:58 AM, David G Dixon wrote:
> 
> > So, Tony, how do they get the voltages required for the various
> > equal-tempered pitches (voltages in a 2^(N/12) ratio)?
> > 
> 

While we're on generating equal-tempered V/Oct, let's just take a moment and consider the elegant simplicity of the pitch generator in the TB303.  That uses a 6-bit DAC for 64 steps, fed from a 5.33V supply rail - and that funny 5.33V is important, because 5.33V / 64 steps * 12 semitones is (near as dammit) 1V :-)

-- 
Gordonjcp MM0YEQ