adjustable/regulated dc power supply

Presented By:MUHSIN BAKHTIAR FAHIMDEPARTMENT OF ECE, KUET

Adjustable DC Power Supply

KHULNA UNIVERSITY OF ENGINEERING & TECHNOLOGY Department of Electronics & Communication Engineering

W E L C O M EE V E RYO N E

2KHULNA UNIVERSITY OF ENGINEERING & TECHNOLOGY

C O N T E N T S

OBJECTIVES

CIRCUIT ANALYSIS

CIRCUIT DESIGN

ADVANTAGES & LIMITATIONS

APPLICATIONS


GOALS

1

6

5

2 4

3

Backup supply to be enlisted

Very marginal and refined tuning

Low cost & lightweight circuit

An adjustable DC power supply

Ensuring short circuit protection

Ensuring under voltage protection

OBJECTIVES


W H Y W O U L D W E P R E F E R T H I S ?

SIZE HANDYDESIGN WEIGHTThe size of the device we built was small and

easy doing.

The compact shape is also noteworthy!

The light weight of this device makes it easier

to deal with.

The design is much more convenient.

Although similar types of devices are found in the market doing the same functions, but why would just we go with our projected circuit? Yes, its because of some preferable dominating advantages stated above.


1

2

3

4

5

BLOCK NETWORKDIAGRAM

INPUT AC SUPPLY

BRIDGE & RECTIFIER CIRCUIT UNDER &

OVER VOLTAGE PROTECTION CIRCUIT VOLTAGE

REGULATIONSHORT CIRCUIT PROTECTION

BACKUP

DESIRED OUTPUT 6KHULNA UNIVERSITY OF ENGINEERING & TECHNOLOGY

D E T A I L S O F E A C H B L O C K

In this part the AC input is converted to DC. First rectifier gives us pulsating Dc, then filter circuit gives us smooth DC.

BRIDGE RECTIFIER & FILTER CIRCUIT

1

The backup circuit consists of a battery & some specific conditions. If the circuit is isolated either over voltage or under voltage, then the circuit gives power to the output.

BACKUP CIRCUIT2

The regulator gives us regulated output. By this we can get our desired voltage level in output.

REGULATOR CIRCUIT3

If the output of the circuit gets shorted to ground, this circuit protects the internal device being damaged by limiting current.

SHORT CIRCUIT PROTECTION4

In this part if the rectified output gets over a range determined by the designer the circuit gets isolated, hence protecting the output.

OVER VOLTAGE PROTECTION5

In this part if the rectified output gets under a range determined by the designer the circuit gets isolated, hence protecting the output.

UNDER VOLTAGE PROTECTION6


RECTIFIERCIRCUIT

INTRODUCT IONINSTRUMENTATION:

1. FUSE2.TRANSFORMER3. DIODES4. BRIDGE RECTIFIER5. CAPACITORS


REGULATED DC

SUPPLY

INSTRUMENTATION:

1. IC LM317T acts as a regulator2. Resistors3. CAPACITORS C2 acts as a ripple remover & C3 reduces transient effect4. VARIABLE resistor is for regulation of output


SHORT CIRCUIT PROTECTION

INSTRUMENTATION:

1. Here R2 & Red LEDacts as a trigger. 2. If the load is shorted the transistor Q2 goes off hence Q2 goes off state. So thecurrent flows through R2 & Red LED indicating short circuit.3. Transistor 2N2905 & 2N2222 are used.


OVER VOLTAGE

INTRODUCT ION

INSTRUMENTATION:

1. Zener diode for reference voltage 2. Rectified output applied across voltage divider portion.3. When rectified output goes above reference voltage then comparator gives output voltage and Q4 becomes on* One thing to say that the relay 1 is switched to operate this region.* Activated for over 34 volts.


UNDER VOLTAGE

INTRODUCT ION

INSTRUMENTATION:

1. Rectified output is applied across voltage divider portion.2. Using zener diode as a reference voltage 3. When rectified output goes under the reference voltage then comparator gives output voltage and LED becomes on

*Activated for less than 22 volts.


C I R C U I TD I A G R A M


RESULTANALYSIS

1. Transformer input=220 V ac. 2. Transformer output=28 V ac, 1000mA ac.3. Output voltage after filtering=36.4V DC.4. Output current after filtering=600 mA5. Over voltage= 34 volts6. Under voltage= 22 volts7. Regulated output=2.3~34.2 V DC.8. Maximum output current=300 mA.9. Maximum short circuit current =68 mA DC.10. Lowest resistence to get shorted= 105 ohm.


MAJOR PROBLEM AND

RELATED SOLUTIONWe were not able to design an uninterrupted circuit if two cases occurred and they are over voltage situation and under voltage situation. If the over voltage or under voltage situation occurred the relay would turn on & then it was grounded. That’s when the rest of the circuits operation stopped and we were not able to get the required output.

For getting uninterrupted circuit we had to use a backup battery of 27V so that when the relay goes on the backup battery will give the needed supply to run the rest of the circuit operation.

i.e. when the circuit is interrupted by short circuited or over or under voltage protected the backup battery will provide continuous power supply for the time being.


L I M I T A T I O N S

1The circuit is vulnerable

2The load is limited as output voltage

3Its output voltage range is only 2.3~37.2

4Circuit efficiency is not so reasonable

5Current rating is very low

6No lifetime guarantee


A P P L I C A T I O N S

AC ADAPTERS

L IKE MOB ILE CHARGERS LABORATORY

DEVICES

LIGHTING

SPEAKERSAND

CHARGER FANS

CENTRAL POWER

DISTRIBUTIONVEHICLES

SPACE STATION


THAT ’S ALL !Thank you for coming today!

IF YOU HAVE ANY QUERY THEN DO ASK ABOUT THAT TO US.
