OSCILLATOR - giantmolecules/SANDIN-IMAGE-PROCESSOR GitHub Wiki

This module contains two oscillators that generates a sine wave output available at JO3, JO4 and a triangle wave output at JO1 and JO2. If the sawtooth switch is down instead of up, the triangle waves becomesa sawtooth and the sine wave becomes an "s" wave. The rotary switch sets the gross frequency range form 1/100 Hz. to 1/2 MHz. R2 is the continuous frequency adjustment. IF the voltage control switch is up, a signal inputted to JI2 will control the frequence of the oscillator in combination with R2. With the switch down the voltage control is disabled but the oscillator is more stable. A sync. level (4 volt) signal into JI1 will trigger the oscillator to stabilize patterns.

CIRCUIT DESCRIPTION

The 8038 is a complete voltage controlled oscillator whose frequency is controlled by resistance R2 and the voltage at pin 8. The 715 is a 10x amplifier and- in combination with the zener diode produces a control voltage at pin 8.

The trimmer associated with the input of the 715 should be adjusted so that the control voltage is centered within its range with 0 volts in. To do this, input a triangle wave to the voltage control input and adjust the trimmer until the voltage that makes the maximum frequency is as positive as the voltage that quenches the oscillator is negative.

The two transistors and zeners are used to trigger the oscillator. When a fast-falling signal is presented at the sync. input this turns the first transistor off which turns the second transistor on. This clamps the oscillator to the bottom of its output wave form.