Mutchus

ASTABLE MULTIVIBRATOR USING OP AMP Astable multivibrator is capable of producing square wave for a given frequency, Amplitude and Duty cycle. The output of OP AMP is forced to swing between positive saturation, +Vsat and negative saturation, -Vsat repeatedly. Which will results in Square wave output. This circuit is also called as Free Running Oscillator. Because, it doesn't requires any trigger pulse to get active. The output of an operational amplifier will be in positive saturation Vsat, if the differential input voltage is negative and vice versa. The differential voltage, Vd=Vc-βVsat. Where β is the feedback factor and βVsat is the potential at non-inverting terminal of the op amp. Consider the instant at which Vc=+Vsat. Now the capacitor charges exponentially towards +Vsat through R. Automatically, Vd increases and crosses zero. This happens when Vc=+βVsat. At the moment Vd becomes positive due to further charging of the capacitor. Output changes to -Vsat. Now capacitor sta...

In clamper circuits a predetermined dc level is added to the output voltage. In other words, the output is clamped to a desired dc level. If the clamped dc level is Positive, the clamper is a POSITIVE CLAMPER. On the other hand, if the clamped dc level is negative, the clamper is called a NEGATIVE CLAMPER. Other equivalent terms used for clamper are dc inserter or restorer. Recall that op amps are designed to operate from a single power supply, such as the 124 series, employ a dc insertion technique. The inverting operational amplifier (op amp) that use this technique is shown in the circuit diagram. The value of the capacitors in these circuits depends on the different input rates and pulse widths. It is also noticed that the output waveforms have an added dc level, which is approximately equal to Vcc/2. This fixed positive dc level is needed to obtain a maximum undistorted symmetrical sine wave. The output voltage of the peak clamper is a net result of ac and dc input voltages applie...