Dc power supply circuit diagram pdf

This circuit comes in nice integrated packages or you can make it using four diodes as well. You will see how we design it in later sections.

Basically, there are two types of rectifier circuits; half-wave and full-wave. However, the one which we are interested in is a full rectifier, as it is more power-efficient than the first one. Nothing is ideal in practical electronics. The output of the rectifier is pulsating and is called pulsating DC. This pulsating DC is not considered good to power up sensitive devices. So, the rectified DC is not very clean and has ripples.

It is the job of the filter to filter out these ripples and to make the voltage compatible for regulation. A capacitor filter is used when we need to convert a pulsating DC into pure or to remove distortion from signal. The best filter in our case is the capacitor. You may have heard, a capacitor is a charge storing device. But actually, it can be best used as a filter. It is the most inexpensive filter for our basic 5V power supply design.

A regulator is the linear integrated circuit used to provide a regulated constant output voltage. Voltage regulation is very important because we do not need a change in output voltage when the load changes.

An output voltage independent of the load is always required. The Regulator IC not just makes the output voltage independent of varying loads, but also from line voltage changes. A regulator is the integrated circuit used to give a constant output voltage regardless of input voltage changes. I hope you have developed some basic concepts of power supply design. Below is the circuit diagram for the said project.

You get the main supply; voltage and frequency can depend on your country, fuse; to protect the circuit, transformer, rectifier, capacitor filter, an LED indicator, and the regulator IC. The block diagram is implemented in NI Multisim software , good simulation software for students and electronics beginners. I encourage spending some time playing with it. Here is the deal, we will design each section first, and then put together each of them to have our DC power supply ready to power up our projects.

You are thinking, I would start the design explanation from the transformer but it is not the case. A transformer is not selected at the very first.

The selection of a regulator IC depends on your output voltage. In our case, we are designing for the 5V output voltage, we will select the LM linear regulator IC.

In the design process, the next thing is, we need to know the voltage, current, and power ratings of the selected regulator IC.

This is done by using the datasheet of the regulator IC. The datasheet of also prescribes to use of a 0. And a 0. Just for extra knowledge, for positive voltage output, we use LM78XX. XX indicates the value of output voltage and 78 indicates positive output. The right transformer selection means saving a lot of money.

We got to know, the minimum input to our selected regulator IC is 7V See above datasheet values. So, we need a transformer to step down the main AC to at least this value. But, between the regulator and secondary side of the transformer, there is a diode bridge rectifier too. The rectifier has its own voltage drop across it i. We need to compensate for this value as well. Why is 1A current? Because the regulator IC has a current rating of 1A, meaning we cannot pass more current than this value.

Selecting a transformer with a current rating more than this will cost extra money. You see in the circuit diagram, the rectifier circuit is made by arranging diodes in some patterns. To make a rectifier we need to select proper diodes for it.

When selecting a diode for the bridge circuit. Keep in mind the output load current, and maximum secondary voltage of the transformer i-e 6V RMS in our case. Instead of individual diodes, you can also use one individual bridge that comes in an IC package.

The selected diode must have the current rating more than the load current i. And peak reverse voltage PIV more than peak secondary transformer voltage. We select the IN diode because it has a current rating of 1A more than our desired rating, and a peak reverse voltage of 50V. Peak reverse voltage is the voltage a diode can sustain when it is reverse biased. Things we need to keep in mind while selecting a proper capacitor filter are, its voltage, power rating, and capacitance value.

The voltage rating is calculated from the secondary voltage of a transformer. Log in with Facebook Log in with Google. Remember me on this computer.

Enter the email address you signed up with and we'll email you a reset link. Need an account? Click here to sign up. Download Free PDF. Alade Abayomi. A short summary of this paper. Download Download PDF. Translate PDF. In most of our electronics projects, there is always a need to convert the incoming mains AC voltage to a regulated DC voltage suitable for the requiring load. A power supply is a device that converts a specific voltage to another voltage that is more convenient while delivering power.

They are mostly used in electrical equipment. Power supply converts the output from an alternating current power to a steady direct current output. The symbol shows which winding has more turn but not usually the exact ratio.

If the voltage is increased, then the current is decreased by the same factor. Transformers energy is dissipated in the windings, core, and surrounding structures. During the positive half-cycles of the input AC voltage: a The diode, D is forward biased and conducts current.

During the negative half cycles of the input AC voltage: a The diode, D is reverse biased and does not conduct current. Bridge Rectifier IC - Bridge rectifier is also available in special packages containing the four diodes required. The various case designs are shown below.

Example of Bridge Rectifier from Suntan product. Suntan is a Hong Kong based manufacturer of bridge rectifiers. The output voltage. The a. Solution : supply across the primary winding is V. Taking transformer turn i. Output voltage neglecting diode resistance ii. Average voltage To find iii.