Voltage Controlled Quadrature Low Frequency Oscillator

The A-143-9 is a voltage controlled sine LFO with 4 outputs. The phase shift between the outputs is 90 degrees (Cosine). the sine shifted by 180 degrees (inverted sine), and the sine by 270 degrees (Inverted cosine) The frequency range is from some minutes to a few kHz), with three selectable ranges. Two frequency control inputs are available: CV1 without attenuator and CV2 with polarizer. Consequently the module can be used as an experimental sine VCO (but does not feature an exact 1V/oct CV input!) The precision CV input will be left to the thru-zero quadrature VCO. Two LEDs display the positive and negative share of the sine output. The core of the module is a so-called quadrature circuit that generates a sine a cosine signal with very low distortion.

The quality of the sine/cosine signals are much better than those generated by a waveform converter with a sawtooth or triangle signal as starting point. The output levels are about 5 V (+/-2.5V) but can be adjusted internally by a trimmer