The 921 Voltage Controlled Oscillator is a variable waveform generator which produces frequencies ranging from 0,01 to 40.000 Hz. Four waveforms are available : sine, triangular, sawtooth and rectangular (with variable duty cycle). Both fixed and variable levels can be obtained from front panel output jacks. Nominal frequency is set manually by the scale, coarse range, frequency and (octave) range controls found at the top of the module. 

Voltage controlled rectangular width is set by a knob and with accompanying voltage input jacks. Clamping point (waveform reset control) may be set with the lower left knob and accompanying trigger input to the left. Multiple frequency control inputs can be plugged into this module in parallel. 

This module functions as both an audio or control voltage generator. 



Frequency Range : 0.01 to 40kHz in two overlapping switch selected ranges (subaudio : 0.01Hz  to 400Hz / audio : 1 Hz to 40kHz) 

Frequency control inputs : 3 (summed) with a voltage to frequency scale factor of 1V/octave. 

input impedance : 100k Ohm 

Manual frequency controls : scale switch (2 or 12 octaves) / Range switch (frequency doubling steps) / coarse range switch (audio - subaudio) 

Rectangular width controls : duty cycle adjustable from 10% to 90% 

Rectangular control inputs : 2 

Rectangular control inputs impedance : 100K Ohms 

Clamping point : Sets restart point of waveform from 0% to 100% of its cycle 

V-trig clamping input : positive edge triggers clamping 

Lowest V-trig step size : from 0 to +2V 

Waveforms : sinewave / triangular / sawtooth / rectangular 

Nominal level : -4dBm (approximately 1.3Vpp) 

Nominal output impedance of Sine / Triangular / and Sawtooth waveforms : 800 Ohms 

Nominal output impedance of Rectangular waveform : 50 Ohms 

Auxiliary outputs : 2 (one normal, one inverted) 

Auxiliary output levels of Sine / Triangular / and Sawtooth waveforms : 0 to 7Vpp (all waveforms are centered aroud 0V) 

Auxiliary output levels of Rectangular : Positive jack  : 0 to +5.5V nominal / negative jack : 0 to -4V nominal 

Auxiliary output levels of inverted Rectangular : Positive jack  : 0 to -4V nominal / negative jack : 0 to +4V nominal 

Rectangular output impedance : positive jack : 0.01 Ohms max / negative jack : 0.06 Ohms max 


Power supply requirements : +12V@50 mA / -12V@50mA