Scaled voltage reference 0V with octave and semitone steps www.haraldswerk.de

Motivation

Scaled Voltage Reference 10V front view.

This module provides high precision CV outputs in 1V (octave) and 83,3mV (semitone) steps. The 1V output goes from zero to +10V. The 83,3mV steps goes from zero to plus 10 steps (semitones). This module is thought for all who are missing octave switches in some modules. Especially in VCO. With this module you can switch octaves and semitones as well. Main reason for this module, because I already have the -5 to +5 scaled Voltage reference, is the additional output on the back for the 10V Add On with fixed voltage outputs. I want those for my test rack to provide fixed 1V positive steps and precision inverters.

Specs and features

High precision output from zero to +10V in 1V steps (octaves)
High precision output in 83,3mV steps, 10 steps (semitones)
Runs on +/-15V and +/-12V
Power consumption below 15mA each rail

Implementation

Schematic

Description:

The precision voltage is derived from the REF102 (IC2). It is crucial to match the resistors in the voltage dividers as good as you can (better than 0.1%). The outputs of the voltage dividers are buffered to avoid loading of the dividers. The resistors around the OpAmps must be matched as well. The one Volt and the 83,3mV steps are added together with IC1A. The four outputs are individually buffered.

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