Regulated Power Supply – Working, Circuit Diagram and Applications

We know that there are different types of electrical & electronic circuits which use a DC power supply. Universally, we cannot use the DC batteries due to expensive as well as require replacement when discharged. In this situation, we require a circuit which can change AC supply to DC supply. A rectifier filter circuit includes a normal DC power supply. The normal DC power supply o/p remains stable if the load is contrast. Although in several electronic circuits it is extremely significant to maintain the DC power supply constant irrespective of alternative AC supply. Otherwise, the circuit will get damage. To overcome this problem, voltage regulating devices can be used. So the blend of the voltage regulating devices by the normal dc power supply is named as DC regulated power supply. This is an electrical device, used to generate the steady DC supply irrespective of alternative AC supply.

What is Regulated Power Supply?

The IC Regulated power supply (RPS) is one kind of electronic circuit, designed to provide the stable DC voltage of fixed value across load terminals irrespective of load variations. The main function of the regulated power supply is to convert an unregulated alternating current (AC) to a steady direct current (DC). The RPS is used to confirm that if the input changes then the output will be stable. This power supply is also called a linear power supply, and this will allow an AC input as well as provides steady DC output. Please refer the link to know more about – Power Supply Classification and Its Various Types

Regulated Power Supply Circuit
Regulated Power Supply Circuit

Block Diagram of Regulated Power Supply

The block diagram of a regulated power supply mainly includes a step-down transformer, a rectifier, a DC filter, and a regulator. The Construction & working of a regulated power supply is discussed below.

Regulated Power Supply Block Diagram
Regulated Power Supply Block Diagram

Transformer and AC Supply

A power supply can be used for providing the necessary amount of power at the precise voltage from the main source like a battery. A transformer alters the AC mains voltage toward a necessary value and the main function of this is to step up and step down the voltage. For instance, a step-down transformer is used in a transistor radio, and a step-up transformer is used in a CRT. Transformer gives separation from the power-line, and must be used even as any modify within voltage is not required.



A rectifier is an electrical device used to convert alternating current into direct current. It can be a full wave rectifier as well as half wave rectifier with the help of a transformer by a bridge rectifier otherwise center tapped secondary winding. However, the rectifier’s o/p can be variable.


A filter in the regulated power supply is mainly used for leveling the ac differences from the corrected voltage. Rectifiers are classified into four types namely capacitor filter, Inductor filter, LC filter & RC filter.

Voltage Regulator

A voltage regulator in the regulated power supply is essential for keeping a steady DC output voltage by supplying load regulation as well as line regulation. For this reason, we can employ regulators like a Zener, transistorized, otherwise 3-terminal integrated regulators. An SMPS-switched mode power supply can be used for supplying huge load current by small power dissipation within the series pass transistor.

Regulated Power Supply Characteristics

The quality of the power supply can be decided by the several factors namely load current, voltage, source and voltage regulation, ripple rejection, o/p impedance, etc. Some of the factors are explained below.

Load Regulation

The load regulation is also known as a load effect. This can be defined as whenever the load current alters from lowest to highest value then the output of the regulated voltage will be changed. This can be calculated by using the following equation.

Load regulation = Vno load – Vfull load

From the above load regulation equation, we can conclude that whenever no-load voltage happens then the load resistance will be unlimited. Similarly, whenever full load voltage happens then the load resistance will be the lowest value. So the voltage regulation will be lost.
% of Load Regulation = (Vno load – Vfull load)/(Vfull-load) X 100

Lowest Load Resistance

The load-resistance on which a current supply supplies its full-load charged current by rated voltage can be called as the lowest load resistance.

Lowest Load Resistance = Voltage full load / Current full-load

Line or Source Regulation

In the power supply block diagram, the input voltage is 230 Volts however in practice; there are significant differences within the AC supply mains voltage. As this mains supply voltage is i/p to the normal power supply, the bridge rectifier’s filtered o/p is approximately directly proportional toward the AC mains voltage. The source regulation can be defined as the modify in regulated o/p voltage for a particular range of low voltage.

Output Impedance

The output resistance of the regulated power supply is very small. Although the exterior load resistance can be changed, approximately no change can be seen within the load voltage. The o/p impedance of a perfect voltage source is zero.

Ripple Rejection

The voltage regulators fix the o/p voltage against the input voltage variations. Ripple is equal to a periodic difference within the i/p voltage. Thus, a voltage regulator satisfies the ripple that approaches with the unregulated i/p voltage. Because a voltage regulator utilizes -ve feedback, the distortion can be decreased with a similar factor as the gain.

Applications of Regulated Power Supply

The applications of the regulated power supply include the following.

A regulated power supply (RPS) is an embedded circuit, used to convert unregulated alternating current into a stable direct current by using a rectifier. The main function of this is to supply a constant voltage to a circuit that should be functioned in a particular power supply limit.

  • Mobile phone chargers
  • Regulated power supplies in different appliances
  • Various oscillators & amplifiers

Thus, this is all about a regulated power supply (RPS). From the above information, finally, we can conclude that an RPS changes unregulated alternating current to a stable direct current. A regulated DC power supply is also named as a linear power supply. This supply will allow an AC input as well as provides a stable DC o/p. Here is a question for you, what is dual dc regulated power supply?