Download Tutorial4 clamper circuit

EC301 Electronics Devices & Circuits-1
TUTORIAL: 4
CLAMPING CIRCUITS
1. A 100V peak square wave with a period of 20ms is to be positively clamped at
25V. Identify a circuit for this purpose. Draw the output waveform.
[Ans:vin=+/-100V,vo=225,25V]
ANS:
For any clamping circuit, apply two steps:
1. Select that input for which diode act as short circuit, find vo and voltage across
capacitor.
2. Take remaining input (D off) and find Vo.
2. Sketch the output waveform for circuit shown below (Figure 4.1)when input is (a)
a sine wave of Vin=40 sin wt and (b) a square wave of 60V peak to
peak.[Ans:vo=-100V,-20V]
Figure 4.1
ANS: Diode arrow downward, negative clamping
3. For practical clamping circuit Rs=100Ω, Rf=50Ω,R=100kΩ,C=2uf and
symmetrical pulse wave signal of amplitude 20V and frequency 5kHz is applied
at t=0. Draw first three cycle of output waveforms.
[Ans:Vo=6.66v,-5.66v,3.28v]
ANS:
4. In Figure 4.2 the values of capacitor C1 and resistor R1 are chosen to provide a
short time constant, so they act as a differentiator network. This results in a brief
pulse of voltage across R1 at each leading edge of the square wave input.
Capacitor C2 and resistor R2 are sized to provide a long time constant, so as to
form an integrator network. This time-averages the brief pulses into a final DC
output voltage relatively free of ripple.
Figure 4.2
Analyze circuit and find out what happens to the output voltage as the input
frequency is increased, assuming the input voltage amplitude does not change.
Can you think of any practical applications?
ANS:
Frequency measurement….
First part , positive clamper and second part a high pass filter..