1. ELECTRONIC DEVICES AND CIRCUITS
TOPIC:
CLAMPER & VOLTAGE MULTIPLIER
LALWANI MOHIT JAIRAMDAS
BRANCH: EC SEM-3
ENROLLMENT NO

2. CLAMPER & VOLTAGE MULTIPLIER

3. CLAMPER:- The clamper circuit is use to clamp the
CLAMPER:- The clamper circuit is use to clamp the input signal without distorting the signal.
CLAMPER
NEGATIVE
CLAMPER
POSITIVE
CLAMPER

4. Positive Clamper
:-The circuit for a positive clamper is shown in the figure.
:-During the negative half cycle of the input signal, the diode conducts and acts like a short circuit.
:-The output voltage Vo  0 volts . The capacitor is charged to the peak value of input voltage Vm. and it behaves like a battery.
:-During the positive half of the input signal, the diode does not conduct and acts as an open circuit.
:-Hence the output voltage Vo Vm+ Vm This gives a positively clamped voltage.
INPUT & OUTPUT WAVEFORMS

5. Negative Clamper
:-During the positive half cycle the diode conducts and acts like a short circuit. The capacitor charges to peak value of input voltage Vm.
:-During this interval the output Vo which is taken across the short circuit will be zero During the negative half cycle, the diode is open.
:-The output voltage can be found by applying KVL.
INPUT & OUTPUT WAVEFORMS

6. VOLTAGE MULTIPLIER:-The voltage multiplier circuit is use to obtain
VOLTAGE MULTIPLIER:-The voltage multiplier circuit is use to obtain higher voltage Vm by keeping transformer turn ratio unchanged
Voltage multiplier
Voltage doubler
Voltage Tripler
Voltage quadruples
Voltage n times
……………….

7. Half-Wave Voltage Doubler
The circuit of a half-wave voltage doubler is given in figure shown below.
:-During the positive half cycle of the ac input, voltage, diodeD1 being forward biased conducts (diode D2does not con­duct because it is reverse-biased) and charges capacitor C1 upto peak values of secondary voltage Vsmax with the polar­ity, as marked in figure.
:-During the negative half-cycle of the input voltage diode D2gets forward biased and conducts charging capacitor C2.
:-For the negative half cycle, the lower end of the transformer secondary is positive while upper end is negative. The polarity of the capacitor C­2.
:-Now starting from the bottom of the transformer secondary and moving clockwise and applying Kirchhoff’s voltage law to the outer loop we have
-Vsmax– Vc1+ Vc2= or
Vc2= Vsmax+ Vc1
= Vsmax + Vsmax
Vc2= 2Vsmax
= Twice the peak value of the transformer secondary voltage

8. :-During the next positive half-
:-During the next positive half-.cycle diode D2 is reverse-biased and so acts as an open and capacitor C2 discharges through the load If there is no load across the capacitor, C2 both capacitors stay charged C1 to Vsmax and C2 to 2Vsmax.
:-If, as expected there is a load connected to the output terminals of the voltage doubler, the capacitor C2 discharges a little bit and consequently the voltage across capacitor C2 drops slightly. The capacitor C2 gets recharged again in the next half-cycle.
:-The input voltage and output voltage waveforms are shown in the figure below.
INPUT:-
OUTPUT:- 2V V

9. Full-Wave Voltage Doubler
The circuit diagram for a full-wave voltage doubler is given in the figure.
:-During the positive cycle of the ac input voltage, diode D1 gets forward biased and so conducts charging the capacitor C1to a peak voltage Vsmax with polarity indicated in the figure, while diode D2 is reverse-biased and does not conduct.
:-During the negative half-cycle, diode D2being forward biased conducts and charges the capacitor C2with polarity shown in the figure while diode D1does not conduct..
:-With no load connected to the output terminals, the output voltage will be equal to sum of voltages across capacitors C1and C2that is,
=VC1+ VC2
=Vsmax+ Vsmax
=2Vsmax
:-When the load is connected to the output terminals, the output voltage VL will be somewhat less than 2 Vsmax.
:-The input voltage and output voltage waveforms are shown in the figure below.

10. :-The input voltage and output voltage waveforms are shown in the figure below.

11. Voltage Tripler and Quadruples
:- voltage tripler and quadrules are shown in figure. :-In operation capacitor C1 is charged through diode Dl to a peak value of transformer secondary voltage, Vs max during first positive half-cycle of the ac input voltage.
:-During the negative half cycle capacitor C2 is charged to twice the peak voltage 2 Vs developed by the sum of voltages across capacitor C1and the transformer secondary.
:-During the second positive half-cycle, diode D3 conducts and the voltage across capacitor C2 charges the capacitor C3 to the same 2 Vs max peak voltage.
:-During the negative half-cycle diodes D2and D4 conduct allowing capacitor C3 to charge capacitor C4 to peak voltage 2 VS max.
:-voltage across capacitor C2is 2 Vs max, across capacitors C1 and C3 it is 3 Vs max and across capacitors C2 and C4 it is 4 Vs max.

12. :-The input voltage and output voltage waveforms are shown in the figure below
VOLTAGE TRIPLER
VOLTAGE QUADRUPLER

13. Some electronic devices, need dc power supply at high voltage with low current. This requirement can be met with either by employing a step-up transformer with a rectifier circuit or by employing voltage multiplier.
Since transformers are very bulky and costly, voltage multipliers are preferred. By using voltage multipliers, the voltage level is usually raised well into the hundreds or thousands of volts.
USES
:-- such as cathode ray tubes
:-- In picture tubes in TV receivers
:-- Oscilloscopes
:-- Computer display
:-- Generally these are used where both the supply voltage and load are maintained constant.
:-- etc
A common type of voltage multiplier used in high-energy physics is the Cockcroft–Walton generator (which was designed by John Douglas Cockcroft and Ernest Thomas Sinton Walton for a particle accelerator, for use in research that won them the Nobel Prize in Physics in 1951).

14. THE END