Regulated Power Supply Block Diagram and Working Principle

Hey, in this article we are going to know the working principle and block diagram of Regulated Power supply. Based on the output characteristics, a regulated power supply is one among the different types of power supply. The main objective to design a regulated power supply is to get always a constant voltage even when the input supply voltage or connected load changes. 

So, a regulated power supply system takes the unregulated alternating or AC power and provides a regulated unidirectional or DC power supply. So, this is involved in voltage step down, rectification, filtration, and regulation. There are huge applications of regulated power supply in sensitive electronic circuits, appliances, bench power supply, testing instruments, automation systems, etc.

Regulated Power Supply Block Diagram

Here, you can see a simple block diagram of regulated power supply.

Regulated Power Supply Block Diagram, Working Principle and Block Diagram of Regulated Power Supply

The most important blocks of this system are,
  1. Transformer
  2. Rectifier
  3. Filter
  4. Regulator


The transformer is a device that transfers the electrical energy from one circuit to another circuit by changing the voltage level. Here, in this circuit, a step-down transformer is used that is used to step down the voltage. Generally, it takes the 220V supply as input and provides 12V or 24V or 6V as the output according to the circuit output requirement. By changing the turns ratio of the transformer, the output voltage can be changed. The transformer is not an essential part of a regulated power supply circuit, it is only used when voltage steps down is required. If the output 230V DC supply is required, then there is no requirement for a transformer.

Rectifier Circuit

The rectifier is an electrical or electronic circuit made of PN Junction Diodes. The main function of the rectifier circuit is to convert the AC supply into a DC supply. It takes the Alternating current or AC power supply as input and gives the direct current or DC power supply as output. The rectifier is the second block of the regulated power supply. Both half and full-wave rectifier circuits can be used. The half-wave rectifier circuit rectifies one-half cycle only and makes more power loss but the full-wave rectifier circuit rectifies both half cycles and makes a very low power loss. For, this reason the center tapped full wave rectifier or bridge rectifier circuit is mostly used.

Filter Circuit

The output of the rectifier circuit cannot provide the pure DC supply. There are some ripple or AC components available in the DC power supply. To remove those ripples or make the DC supply pure, a filter circuit is used. The output of the rectifier is connected to the input of the filter circuit. Generally, a pure capacitor filter, LC filter, or pi filter is used. According to nature, a capacitor block DC and allow AC, so it can be connected in parallel for the filtration. On the other hand, an inductor can block AC and allow DC, so it can be connected in series for filtration purposes. The pi filter uses both the inductor and capacitor in the same circuit for the filtration.

Regulator Circuit

It is the last and most important block of the regulated power supply. The regulator actually does the regulation. The regulator circuit uses different types of regulating components and devices such as a Series inductor, Zener Diode, IC 78XX series, IC 317, etc. A Zener diode can regulate voltage by just connecting it in reverse bias. IC 7805 is the most common usable regulator IC. It always provides a constant 5V DC voltage as its output. A Zener diode may not have the 100% efficiency but the integrated circuits provides the most possible efficiency. Zener diode helps to regulate the voltage only whereas the voltage regulator ICs can take care of load current also.

There are two types of Regulators are there - Series Regulator and Shunt Regulator. In the series regulator circuit the regulating element is connected in series whereas in the shunt regulator circuit, the regulating element is connected in parallel. Series regulator has more efficiency than shunt regulator.

Regulated Power Supply Working Principle

Now, let's understand the working principle of the regulated power supply. For example, we take a circuit whose output voltage rating is 12V and input voltage rating is 230V. So, first, the step-down transformer steps down the voltage from 230V AC to 12V AC. Then the rectifier circuit converts the 12V AC coming from the transformer into 12V DC. Then the filter circuit that is connected at the output of the rectifier circuit, will filter the impure DC coming from the rectifier output into pure DC. At, last the regulator circuit keeps the DC voltage level constant at 12V even when the input supply of the circuit changes or connected load to the circuit varies.

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Regulated Power Supply Block Diagram and Working Principle Regulated Power Supply Block Diagram and Working Principle Reviewed by Author on November 10, 2021 Rating: 5
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