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Figure 1: Positive Feedback Amplifier.
When the feedback signal (Xf) is in phase with the source signal (Xs), then such type of feedback is referred to as positive feedback or regenerative feedback amplifier. A feedback amplifier circuit is illustrated in figure 1.
(a) Circuit Diagram
(b) Phasor Diagram
Figure 1: Parallel Resonance Circuit.
In a parallel resonant circuit, the inductor L and capacitor C are connected in parallel as shown in Fig. 1 (a).
An equation relating the relative motion of the rotor axis with respect to stator field in time domain is known as swing equation.
or
The equation which describes the behavior of a synchronous machine during transient period is known as swing equation.
Single Tuned Amplifier circuits employ a single resonant circuit in the collector of the amplifier. The signal input is usually given to the amplifier through an input transformer but may also be fed through R-C coupling.
(a)
Schmitt trigger uses positive feedback in its circuit. Hence it is also called as regenerative comparator. Figure (1) shows an Op-amp Schmitt trigger.
Figure 1: Schmitt Trigger.
Zero Crossing Detector (ZCD) is a basic comparator circuit, whose reference voltage level is set at zero. It detects the zero crossing in the applied input AC signal is referred to as zero crossing detector. It is also called a sine to square wave converter.
Figure 1: Zero Crossing Detector.
