This document discusses rectifiers, which are devices that convert alternating current (AC) to direct current (DC). It explains that AC current periodically changes direction, while DC current flows in one constant direction. A rectifier uses a step-down transformer to lower the voltage of an AC source, and then diodes to allow only one half of the AC cycle to pass to the load. When a diode is forward biased during the positive half cycle, it acts like a closed switch and allows current to flow. During the negative half cycle, when the diode is reverse biased, it acts like an open switch and blocks current flow. This has the effect of converting the alternating current into a pulsing direct current.

1. RECTIFIER
BY
PROF VISHNU NARAYAN SAXENA

2. RECTIFIER IS A DEVICE THAT CAN CONVERT AC IN TO DC
SO THERE ARE TWO QUESTIONS
WHY WE NEED TO CONVERT A.C.
IN TO D.C.
AND WHAT IS A.C. AND WHAT IS
D.C.

3. ALTERNATING CURRENT IS THAT CURRENT WHICH
DIRECTION REVERSE PERIODICALLY
AND
IN DIRECT CURRENT IS THAT CURRENT IN WHICH THE
DIRECTION OF CURRENT REMAIN SAME

4. Building Blocks of Rectifier
1.Step Down Transformer
The function of step down
transformer is to convert
high A.C. Voltage(230 V) to
Low A.C. Voltage (15V,12V
etc)Because we can't apply
high ac voltage to diode
directly
2. Semiconductor Diode

5. Diode is a semiconductor switching device Which has two terminal
1. Anode
2. Cathode
Diode can be conncted in any circuit either in forward bias or reverse bias

7. FORWARD BIAS: When anode is connected with +ve terminal of
battery and cathode is connected with –ve terminal of Battery Diode is
in forward bias and its resistance drop down to 0(r = 0) and it behaves
like a close switch

8. REVERSE BIAS: When anode is connected with -ve terminal of
battery and cathode is connected with +ve terminal of Battery
Diode is in reverse bias and its resistance rises up to infinite
and it behaves like an open switch

9. AC Voltage is first stepped down
then applied to the diode
During +ve Half Cycle Point A Will be
at positive potential whereas point B
will be at –ve Potential
Diode D Will be in Forward Bias and
behave like a close switch
And positive half cycle will be passed
as it is As Shown in fig

10. During Negative Half Cycle Point A
will be At Negative Potential As
Compared to Point B So Diode is in
Reverse Bias and Behaves Like an
Open Switch and negative half cycle
does not passes to the load
resistance

11. NOW WORKING OF RECTIFIER

12. DURING POSITIVE HALF CYCLE DIODE IS IN FORWARD BIAS AND
BEHAVES LIKE A CLOSED SWITCH AND POSITIVE HALF CYCLE PASSES
TO THE LOAD RESISTANCE
DURING NEGATIVE HALF CYCLE DIODE IS IN REVERSE BIAS AND
BEHAVES LIKE AN OPEN SWITCH AND NEGATIVE HALF CYCLE DOES NOT
PASSES TO THE LOAD RESISTANCE
IN THIS WAY HALF WAVE RECTIFIER CONVERT HALF CYCLE OF AN
A.C. VOLTAGE TO THE D.C. VOLTAGE