This document discusses a student project to build a voltage doubler circuit using an LM555 timer integrated circuit. The circuit works by charging and discharging capacitors in a way that produces an output voltage that is twice the input voltage. It can be used when a higher output voltage is needed than what a single power supply can provide. The circuit was built and tested, with an input of 12V producing an output of around 18V, doubling the input voltage. Potential applications of voltage doubler circuits include increasing low voltages to high voltages for experiments, and in power converters and isolated resonant converters.

1. SREENIDHI INSTITUTE OF SCIENCE AND
TECHNOLOGY
LINEAR AND DIGITAL IC APPLICATIONS LAB
PROJECT ON VOLTAGE DOUBLER
B.TECH 3/4 YEAR SEMESTER-1
EEE
BY
K.KRISHNAVENI (12311A0227)
K.KARTHIK (12311A0226)
K.KAPIL (12311A0225)

2. VOLTAGE DOUBLER
Most of this project is circuit used for doubling the
voltage uses the principle of charging and discharging
the capacitor. The voltage doubler circuit described
below is used to double the input DC power by using
IC 555 timer with capacitors and diodes. This circuit is
useful when higher voltage level is required from a
single lower voltage power supply.
This voltage doubler project is based on 555 timer
wired in astable mode means it will produce a square
wave at a frequency of 2KHz approx with the help of
components R1,R2 and C1.When input power is
supplied to the circuit an output is produced at PIN3 of
IC1.
This dc voltage doubler circuit produces a voltage that
is twice its voltage supply. This is useful when a higher
voltage level is needed out of a single lower voltage
power supply. Since the current consumption levels are
low in such cases, the circuit can be built with minimal
resources.

3. Voltage Doubler Circuit Schematic
The electronic circuit is basically a square wave
generator using the common LM555 timer IC. It is
followed by a final stage made of transistors T1 and T2.
The actual doubler circuit is made of D1, D2, C4 and C5
components.
The 555 dc voltage doubler timer IC works as an
astable multivibrator and generates a frequency of
about 8.5 kHz. The quare wave output drives the final
stage made of T1 and T2. This is how the doubler
works: by a low amplitude of the signal, transistor T1
blocks while T2 conducts. The minus electrode of the
capacitor C4 is grounded and charges through D1. By a
high amplitude of the signal, transistor T1 conducts
while T2 blocks. However, capacitor C4 cannot
discharge because it is blocked by D1. The following
capacitor C5 is therefore charged with a combined
voltage from C4 and the power supply (12V input).

4. On standby, the circuit delivers around 20 volts. The
maximum load must not exceed 70 mA. The actual
output voltage is around 18 volts giving an efficiency
rating of 32 %.
On lower current ratings, the voltage is higher.
If a stable voltage lever is desired, a 3 pin voltage
regulator IC can be added at the output. The regulator
IC’s own current consumption must be added to the
total current consumption which must not exceed 70
mA.
A voltage doubler is an electronic circuit which
charges capacitors from the input voltage and switches
these charges in such a way that, in the ideal case,
exactly twice the voltage is produced at the output as
at its input.

5. The simplest of these circuits are a form
of rectifier which take an AC voltage as input and
output a doubled DC voltage. The switching elements
are simple diodes and they are driven to switch state
merely by the alternating voltage of the input. DC to
DC voltage doublers cannot switch in this way and
require a driving circuit to control the switching. They
frequently also require a switching element that can be
controlled directly, such as a transistor, rather than
relying on the voltage across the switch as in the
simple AC to DC case.
Voltage doublers are a variety of voltage
multiplier circuit. Many (but not all) voltage doubler
circuits can be viewed as a single stage of a higher
order multiplier: cascading identical stages together
achieves a greater voltage multiplication
OUTPUT

6. APPLICATIONS
 A doubler can increase a low voltage to a very high
voltage by adding stages the application is study of
high voltage behavior to plasma study to
entertainment of globe arcing to ions generators to
eliminate odors.
 voltage-doubler in rectifying LLC multi-resonant
converter.
 Voltage doubler is also used in isolated resonant
converters.
 It is used to produce a voltage that is twice its
voltage supply.