Voltage multiplier

Voltage multipliers are AC-to-DC power conversion devices, comprised of diodes and capacitors, that produce a high potential DC voltage from a lower voltage AC source. Multipliers are made up of multiple stages. Each stage is comprised of one diode and one capacitor.

1. • VOLTAGE MULTIPLIER

2. Introduction: What is a Multiplier?•
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•Voltage multipliers are AC-to-DC power
conversion devices, comprised of diodes and
capacitors, that produce a high potential DC
voltage from a lower voltage AC source.
Multipliers are made up of multiple stages.
Each stage is comprised of one diode and one
capacitor.

3. Types of voltage multiplier#%&
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Depending on the output voltage, multipliers
cajn be of different types
 Voltage doublers
 Voltage tipplers
 Voltage quadrupler

4. Voltage doublers •+((%
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A Voltage doubler produces a d.c. voltage
almost twice the rms value of the input a.c.
voltage.
Voltage doubler can be of two types;
Half wave voltage doubler
 Full wave voltage doubler

5. • •• • • Half wave voltage doubler •• •••• • •
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The circuit for a half wave voltage doubler.
During the positive half cycle of the secondary
voltage diode D1 conducts and D2 is cut off.
Now capacitor C1 charges to the peak
rectified voltage Vm, with polarity shown in
the figure. During the negative half cycle, the
secondary voltage comes in series with
voltage across the capacitor C1.

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Thus C2 will try to charge towards 2Vm(Vm of
the input and Vm of the capacitor C1. After
few cycles the voltage across the capacitor C2
will be equal to 2Vm Since diode D2 acts as a
short during the negative half-cycle (and
diode D1 is open), we can sum the voltages
around the outside loop. i.e;
−???????????? − ????????????1−????????????2=0 (or) −???????????? − ???????????? −????????????2=0
from which, ????????????2=2????????????

7. Circuit Diagram

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In the circuit capacitor C1 will discharge in the
negative half cycle. Again in the positive half
cycle, it starts charging. Thus the half wave
voltage doubler supplies the voltage to the
load in one half cycles. Therefore regulation of
the half wave voltage doubler is poor.

9. • Full wave voltage doubler



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Another voltage doubler circuit called full wave voltage
doubler is shown in fig. During the positive half cycle of
the secondary voltage diode D1conducts, charging the
capacitor the capacitor C1to the peak voltage Vm. At
this time diode D2 is non-conducting. During negative
half cycle diode D2conducts, charging capacitor C2to
Vm, with polarity as marked, while diode D2is non-
conducting. Since both capacitors C1and C2are in
series, the final output voltage is approximately 2Vm.
This circuit is called full wave voltage doubler because
one of the output capacitor is being charged during
each half cycle of the input voltage

10. Circuit diagram

11. Voltage tripler•
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•The voltage tripler arrangement adds another
diode/capacitor set.
•+ half-cycle: C1 charges to Vp through D1,
• - half-cycle: C2 charges to 2Vp through C2,
• Next + half-cycle: C3 charges to 2Vp through
C3.
•Output is across C1 & C3.

12. Circuit diagram

13. • Voltage Quadruplers•


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•The voltage tripler arrangement adds another
diode/capacitor set.
•+ half-cycle: C1 charges to Vp through D1,
• - half-cycle: C2 charges to 2Vp through C2,
• Next + half-cycle: C3 charges to 2Vp through
C3.
• Next - half-cycle: C4 charges to 2Vp through C4
• Quadruple Output is across C2 & C4.

14. Circuit diagram

15. Common Multiplier Applications &*+
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Originally used for television CRT's, voltage
multipliers are now used for lasers, x-ray
systems, traveling wave tubes (TWT's),
photomultiplier tubes, ion pumps,
electrostatic systems, copy machines, and
many other applications that utilizehigh
voltage DC.