PS110 Voltage Controlled Oscillator

by Antti Pussinen and Wolfgang Spahn

PS110 Voltage Controlled Oscillator the a saw wave core for a one volt per octave oscillator. The wave shaper board for the VCO is here: PS110_Wave Converter

A Voltage Controlled Oscilator, or vco, is the heart of any musical synthesizer. It usually forms the starting material for subtractive audio synthesis. An analog VCO of this kind creates an audible waveform by charging and discharging a capasitor. Voltage control enables one to control the frequency of the produced waveform in selected musical scale and play notes or a melody.

We are planing to design a wave shaper board to the VCO, adding the rest of the waveforms and a linear frequency modulation input.

Features:

  • compatible with euro rack format
  • built in power supply for stable voltage response and possibility to power over usb cable
  • 1V/octave response(configurable to 1v/hz)
  • exponential frequency modulation with attenuation potentiometer
  • sync input with sync level adjustment
  • saw wave 10vpp output

Additional features with wave shaper board:

  • sine, square, pulse width modulation and triangle outputs 10vpp
  • pwm modulation cv input
  • Linear frequency modulation with attenuatio potentiometer

For tuning the oscillator one needs the calibration keyboard.
And for powering the board over USB one need the USB to FFC Connector.

The board is based on the Formant Pro, Modulares Sound System MMS2000, Hans-Joachim Helmstedt - Elektor Verlag - ISBN 3-89576-099-4.


Audio Test

PS110 clean test:



PS110 exp fm test:



PS110 sync test:




Schematic



Paper-PCB

Faceplate


Here is 300dpi JPG:


Parts

  • Resistors: 1x 14 Ohm, 3W (3x 39 Ohm, 1W), 1x 330 Ohm, 2x 470 Ohm, 1x 750 Ohm, 3x 1 K, 1x 1.5 K, 1x 2.37 K (2.4 K), 1x 4.7 K, 2x 10 K, 1x 12 K, 1x 51 K, 1x 56 K, 6x 100 K, 1x 240K, 1x 1 M
  • 2x Diode 1N4148
  • 2x Transistors BC547
  • 1x LED 2mA 3mm1x Elko 10µF
  • Trimpoti: 2x 500, 1x 10K, 1x 100K
  • Poti: 1x 100 K log, 1x 100 K lin, 1x 47 K log, 1x 47 K lin
  • Capacitors: 1x 100pF, 1x 3.3nF, 1x 10nF
  • 1x OpAmp TLO74
  • 1x Transistor Array CA3086 (there is a Russian substitute UL1111, or the SMD chip LM3046)
  • 1x Schmitt Trigger 74LS132
  • 1x DC-DC Converter SIM2-0512D (5V to +-12V)
  • 3x IC-Socket 14Pin
  • Pin Strip 10 Pins
  • Pin Header 3 Pins
  • 1x Jumper
  • 1x 2×8 Pin Socket
  • Additional USB Power Adapter:
    • Mini USB Socket
    • Pin Strip 2×8 Pins