DEPARTMENT OF COMPUTER & SOFTWARE
ENGINEERING
COLLEGE OF E&ME, NUST, RAWALPINDI
Subject Name
Electronic Devices & Circuits
PROJECT REPORT
SUBMITTED TO:
Sir Ihsan-Ullah
Sir Azmat
SUBMITTED BY:
Students Name
1. Muhammad Mussa Kazim -404047
2. Osaid Amjad -
3. Sikandar Hussain -
DE- 44 Dept C&SE
Syndicate-A
Submission Date:
9th Jan, 2024
AC TO DC POWER SUPPLY
Working Principle:
Introduction:
The conversion of alternating current (AC) voltage to direct current (DC) power supply is a
fundamental aspect of electronic systems and power electronics. Many electronic devices, ranging
from simple gadgets to complex industrial machinery, require a stable and regulated source of DC
power for proper operation. In this project, we aim to design and implement a circuit that efficiently
converts AC voltage from the mains power supply to a well-regulated DC power supply.
Working Principle:
The fundamental working principle of converting AC voltage to DC power involves rectification
and filtering processes. The key components of the conversion circuit include a transformer,
rectifier, and filter.
1. Transformer: The AC voltage from the mains power supply is first passed through a
transformer. The transformer steps down or steps up the voltage based on the design requirements.
The primary coil of the transformer is connected to the AC source, and the secondary coil provides
the transformed voltage.
2. Rectification: The transformed AC voltage is then fed into a rectifier circuit. The rectifier
converts the AC voltage into pulsating DC voltage. There are two types of rectifiers commonly
used: half-wave rectifiers and full-wave rectifiers. Half-wave rectifiers allow only one-half cycle of
the AC waveform to pass, while full-wave rectifiers permit both halves.
- Half-Wave Rectification: Only positive half-cycles of the AC waveform are allowed to pass
through.
- Full-Wave Rectification: Both positive and negative half-cycles are utilized, resulting in a
smoother DC output.
We will be using the Full Wave Rectification for our Project.
3. Filtering: The pulsating DC voltage obtained from the rectifier contains unwanted ripples. To
smooth out these ripples and provide a stable DC output, a filter is employed. Commonly used
filters include capacitors and inductors. Capacitors store charge during the peak voltage periods and
discharge during the lower voltage periods, effectively reducing the ripple.
4. Voltage Regulation: To ensure a stable and well-regulated DC output, voltage regulation
circuits such as voltage regulators or zener diodes may be added. These components maintain a
constant output voltage, even in the presence of variations in the input voltage or load conditions.
By combining these elements, the AC voltage is efficiently converted to a regulated DC power
supply, providing a reliable source for powering electronic devices.
In this project report, we will discuss the design considerations, component selection, circuit
analysis, and experimental results, highlighting the efficiency and effectiveness of the AC to DC
power supply conversion. Additionally, any challenges faced during the implementation
will be addressed.
We can use other types of ICs or Zener Diodes to Achieve Voltages Other than 5Volts.
Hardware Components Used:
//
Requirements:
Output: The power supply should have three separate outputs
Voltage Output Current Rating
2.7 to 24V 0.5 A
-2.7 to -24V 0.5A
5V 1A
Schematic Diagrams:
Full Circuit:
2.7 to 24V and 0.5A:
-2.7 to -24V and 0.5A:
5V Fixed with 1A:
There is only a slight Difference of some point values in Required Values and Simulated Values.
5V Circuit Explanation:
In this circuit, we have a TIP31 BJT, which is like a traffic cop controlling the flow of electricity.
There's also a 1N5919B Zener diode, which acts like a reference point for voltage, always keeping
it around 5.6 volts.
When the incoming electricity is more than 5.6 volts, the Zener diode steps in to make sure the
voltage stays at 5.6 volts. The TIP31 BJT helps with this by managing how much electricity goes
through the Zener diode and the load resistor, which is like the device you're powering.
The 5Ω load resistor is simply the thing you're powering, and there's a 340Ω resistor that makes
sure the Zener diode doesn't get too much electricity.
The whole point of this setup is to make sure you get a steady 5 volts to power your device. If you
want to make it work even better, you might add capacitors to reduce electrical noise and heat sinks
to keep things cool. That way, your circuit is reliable and efficient.
-ve Voltage Circuit Explanation:
A transformer is connected to a power source and gives an output with a center tap. One part of it
goes through a diode bridge to turn it into a positive supply, and then a 4700uF capacitor helps
smooth out any bumps in the voltage. This smoothed-out voltage goes into an LM337K IC, which
is like a regulator making sure the voltage stays steady.
To adjust the voltage, there's a 10kΩ potentiometer and a 560Ω resistor connected to the LM337K
IC. This setup is like a volume control for the voltage. The LM337K IC makes sure the voltage is
just right, and the potentiometer helps tweak it.
To clean up the voltage even more, there's a 10nF capacitor and a 50Ω resistor. They work together
to get rid of any leftover bumps in the voltage. The whole idea here is to get a steady and controlled
negative voltage as the output.
+ve Voltage Circuit Explanation:
The other input of the transformer goes through a diode bridge to turn it into a positive supply. This
positive output is connected to a 4700uF capacitor to smooth out any bumps in the voltage. The
capacitor's output then goes to the input of an LM317EMP IC, acting like a traffic cop to keep the
voltage stable.
To control the voltage, there's a potentiometer and a 550Ω resistor connected to the LM317EMP
IC. It's like a knob to adjust how much voltage we want. The potentiometer has a value of 10kΩ,
which means we can be very precise in setting the voltage.
To make sure the voltage is super smooth, there's a 10nF capacitor and a 50Ω resistor. They team
up to get rid of any leftover bumps in the voltage. The main goal here is to get a steady and
controlled positive voltage as the output.
Circuit Implementation:
Conclusion:
This project shows how to use a bridge rectifier to turn a wavy AC electrical signal into a steady
DC power. The setup gives three different outputs:
1. Terminal A always provides a steady 5V DC power, giving a reliable and consistent source of
energy.
2. Terminal B provides a range of negative voltages from -2.7 to -24V DC, which can be handy for
different applications needing positive voltage values.
3. Terminal C is set up for positive voltages, offering a range from +2.7V to +24V.
By using the bridge rectifier and other parts in the circuit, this project successfully changes AC to
DC, making sure each output terminal gets the specific voltage it needs.
