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DIY MFOS Voltage Quantizer KB

We always recommend visiting the MFOS website before building where the latest 'offical' information and news can be found. Here on the Soundtronics website, you will find selected information from the MFOS site plus additional information and resources to aid the building and maintaining of your MFOS synth. This is not going to happen over-night but during the course of 2014, it will start to take shape as we document our experiences in the construction of these modules. We would also like to include any experiences, hints and tips from customers as well so feel free to contact us or simply post a comment using the form at the foot of this page.

Introduction to the MFOS Voltage Quantizer

A voltage quantizer takes a continuously variable input voltage and outputs a stepped (or quantized) voltage. Whereas the input voltage might ramp up from 0 to 1V continuously the output voltage of the quantizer will be discrete steps of .083V. In normal mode this quantizer always starts at digital 1 or .083V. As the input voltage starts to ramp from 0 up to 1 volt the output will step to .1666V, .2499, .3332, etc up to 1.0V. The circuit also features a whole step mode in which the in to out conversion is quantizd to steps of .1666V. It also features a fourth step mode in which the in to out conversion is quantizd to steps of .3332V. Useful with sample and hold circuits to bring voltages into musical scale steps (half, whole or fourths). Useful with sequencers to bring voltages into musical scale steps (half, whole or fourths).

Features

  • Converts continuous voltage input to discrete .0833 voltage steps.
  • Also provides whole step and fourths mode (.1666V and .3332V steps).
  • Low cost parts used in the A/D and D/A circuits.
  • Adds 12 tone (or whole or fourth tone) musical dimension to S&H outputs.
  • Eases sequencer set up by correcting notes to discrete steps.
  • Conversion time varies from sub millisecond to 1.26 millisecond (full count)

Documentation & Downloads

Deviations from MFOS Standard Design

Rather than use two toggle switches, we decided to use a rotary wafer switch set to 3 positions - Whole, Half & fourths. Connect up the switch as follow (SS references are to the MFOS circuit and wiring diagrams):

1. Remove 'Stop' tab washer, with switch front facing you, rotate fully anti-clockwise. Insert 'Stop' tab washer into position 3.

2. The SS? numbers refer to the PCB connection, the letters and numbers refer to the connections on the back of the switch.

SS1 to A

SS2 to 2

SS3 to 1

SS4 to B

SS5 to 5 & 6 (solder these two switch connections together

SS6 to 7

Under Construction