1. Rectifiers:
 Rectifier is a device which converts AC voltage into DC voltage,
It is most crucial part of DC power supplies.
2. Clippers:
 Clipper is a circuit which can clip the AC input waveforms from
anywhere depending upon the design of the circuit.
3. Clampers:
 Clamper is an electronics circuit that can shift the dc levels of an
input AC waveform.
4. Multipliers:
 A multiplier is a circuit whose output is a multiplied version of
its input.
 Peak Value:
 Peak value is the highest(lowest ) value of any signal.
 DC or Average Value:
 DC value is the average value of a signal. It can be calculated by
integrating the signal over a period and dividing by that period.
1 𝑇
𝑥
𝑇 0
=
𝑡 𝑑𝑡
 DC value of a pure sinusoidal signal is zero.
 DC value of a pure dc signal is equal to its peak value.
 RMS Value:
 It is the root mean-squared value of a signal. It is calculated by
squaring, averaging and square-rooting the input signal in the
respective order.
 =
1 𝑇
𝑇 𝑜
𝑥 2 𝑡 𝑑𝑡
𝑉𝑝
 RMS value of a pure sinusoidal is 2 , where Vp is the peak value.
 RMS value of a pure dc signal is equal to its peak value.
 Usually AC signals are represented by their peak values or
rms values
 In Pakistan, the AC power supply has rims value of 240V
and frequency of 50 Hz.
 Rectification is a process by which an AC signal is
converted to a pulsating dc signal
 A pulsating dc signal is a signal whose magnitude
varies with time but doesn’t change direction.
 The dc value of a pulsating signal is non-zero. It can
be used for non-precision dc sources like batterychargers.
 For precision applications we need non-pulsating
output. For that we have to filter the rectified output
and also a special circuit called voltage regulator.
 It is divided into two types:
 Half-Wave Rectifier: Convert one cycle (positive or negative)of
the input waveform to pulsating dc.
 Full –Wave Rectifier: Convert both cycles of input waveform into
pulsating dc.
 A diode in series with an AC supply acts as a half-wave
rectifier.
 In an ideal diode, for positive half cycle the diode will be
forward biased and conduct since its VD>0 . A practical
diode will conduct in positive half-cycle when ac voltage
increases to its conducting voltage. Consequently, output
voltage follows the input voltage with a difference of
conducting voltage which is 0.7V for Si and 0.3V for Ge.
 For negative half-cycle the diode will be reverse biased
and will not conduct.
 If direction of diode is reversed, its conducting and nonconducting cycles will be reversed.
 The DC value of a half-wave rectified output is
𝑽𝒑
𝝅
.
 The maximum reverse voltage the diode will experience
is Vp.
 PIV ≥ 𝑽𝒑
 It converts both cycles of the input waveform to
pulsating dc waveforms.
 In positive half cycle two of the four diodes will
conduct and in negative half cycle the remaining two
diodes will conduct. Both times the direction of
current flow will be in same direction.
 The average value of a full-wave rectifier is twice that
of half-wave rectifier i.e.
𝟐𝑽𝒑
𝝅
 The voltage drop across the output is equal to input
voltage minus two conducting diode voltages i.e. 1.4V
for Si diodes and 0.6V for Ge diodes.
 PIV ≥ 𝑽𝒑
 For high precision applications the drop of 1.4V can be a
problem. It can be solved using a center-tapped
transformer.
 Centre tapped transformer has two secondary coils. Voltage
in one varies in phase with the primary coil while opposite
is true for the second coil. The magnitude of both of them
are half as compared to primary coil.
 When input is positive the in-phase secondary will forward
bias one of the diode and when input is negative the outof-phase
 It requires only two diodes and the output voltage is one
diode voltage less than the input voltage.
 PIV ≥ 𝟐𝑽𝒑