Sawtooth voltage controlled oscillator

  
B sawtooth voltage controlled oscillator First, the output voltage of the comparator is a negative potential maximum. Then the output to the inverting input terminal
Sawtooth voltage controlled oscillator - schematic

R1 via the relaxation oscillator at the output of the relaxation oscillator to generate a positive phase voltage ramp. When the ramp voltage reaches the trigger point, input of the comparator has also been positive potential maximum. This positive potential so that the relaxation oscillator ramp voltage gradually decreased from the highest point, and changes to the negative voltage direction. Ramp voltage in this direction continued to decline until the comparator until the next trigger point. Then the comparator input also dropped to a negative potential maximum, and continue to repeat this cycle, the output of the continuous triangular wave. When the input of the relaxation oscillator with adjustable DC voltage control, the triangular wave oscillator becomes a sawtooth oscillator. Voltage control signal may be a sine wave or sine wave, if the input signal terminal with controlled thyristor PUT feedback capacitor in parallel, so that each ramp voltage slope off at a specified level, as shown in Figure 16-22. First, a sawtooth oscillator initially negative DC input voltage - Vin generating at the output a positive phase ramp. When a male thyristor controlled single-junction electrode when the gate voltage exceeds the output ramp voltage 0.7 V, single-junction is triggered thyristor conduction. Set the value of the gate voltage roughly equal to the expected peak of the sawtooth voltage. When PUT conduction, discharge the capacitor quickly, as shown in Figure 16-22 (b). Because PUT positive phase relationship between voltage VF, the capacitor will not be fully discharged to zero. PUT discharge process continues until the current below the holding current. At this single-junction off thyristor will, once again begins to charge the capacitor, thus creating new output voltage ramp. This cycle is repeated, the output signal would be a repeat of the sawtooth waveform, amplitude and period of the sawtooth wave may be changed by the PUT gate voltage must be adjusted.




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