05-06-2013, 01:49 PM
RC CIRCUITS
RC CIRCUITS[.doc (Size: 87 KB / Downloads: 21)
Objectives:-
You will be able to
• Draw voltage & Current graphs for a capacitor being changed via a resistor from a dc voltage source & explain the shape of the graphs.
• Write the equation for instantaneous capacitor voltage in a series RC Circuit with a DC voltage source. Calculate the capacitor and resistor voltages at any time from the instant of supply switch-on when the capacitor is initially uncharged and when it is already partially charged.
• Define the time constant for a series RC Circuit and derive equations relating various levels of capacitor voltage, charging time, and time constant. Perform calculations involving the circuit time constant.
• Show how the input circuit of an amplifier can be represented as an RC Circuit. Perform calculations involving R, C, the circuit upper cutoff frequency the rise time at the output, the circuit lower cutoff frequency and the tilt on the top of a rectangular output waveform.
• Sketch differentiating & integrating circuits explain their operation and determine the expected output voltages for given inputs.
Introduction:-
When a capacitor is charged from a dc voltage source through a resistor the
Instantaneous level of capacitor voltage may be calculated at any given time. There is a definite relationship between the time constant of an RC circuit and the times required for the capacitor to charge to approximately 63% and 99% of the input voltage. Also, an important relationship exists between the time constant of a circuit and the rise time of the output voltage from the circuit. Depending upon the arrangement of the RC circuit, it may be employed as an integrator or a differentiator.
Aim:-
To design an integrator and a differentiator and observe the output for Square wave inputs.
Components and Equipments:-Resistors, Capacitors, function generator, CRO, Groove board, BNC, Patch cards, clips.
Procedure1:-
Differentiating circuit:
• Construct an RC differentiating circuit as in figure1.1 using R = 2.2K and C = 0.1μf.
• Apply a ±10V, 500Hz square wave input and monitor both input & output waveform on a (dc- coupled) Oscilloscope.
• Sketch the input and output waveform for f = 500Hz carefully noting the amplitude and the phase relationship between input & output.
• Change the signal frequency to 50 Hz, 5KHz & 50KHz in turn. Sketch the input & Output waveforms in each case.
• Change the input to triangular waveform and again repeat the above procedures .