Through the help of 230 volt AC power supply we can easily get 9 volts at the output. For building that circuit there is need of some components that will give you smooth 9 volts at the output. There is need of rectifier that that contain four diodes that are acting like a full bridge. This will convert ac into dc volts. But the voltage is not smooth at that stage, there are a lot of ripples are present in that output wave. Then after this, there is need of smoothing capacitor. This will help to smooth the dc volts.

But at that stage there is no 9 volts at the output. For that there is need of voltage regulator. This will give exact 9 volts at the output. The name of this voltage regulator is LM7809. In the next part in place of LM7809 there is need to attach the zener diode, and it is acting like a voltage regulator. In that report both circuits will he designed on multisim and its output will be checked in a proper way. All waveforms will be analysed and explained according to the simulated circuit.

Calculations of lM7809 of DC Power Supply

According to the given scenario the input voltages are given as 230 volts and the output current will be 0.25 amperes.

Then the value of resistance will be

This means that the nominal value of Resistance will be 920 ohm and it can be 5%.

The frequency of the circuit is set up to 50 Hz

According to the given scenario the power rating can be calculated through

The voltage rating of the resistor can be calculated

This shows that the transformer has to step down the voltage so that the resistor is able to bear it easily.

Calculation for zenar diode of DC Power Supply

According to the requirement the output voltage will be about 9 volts. Then set the breakdown voltage of the zenar diode at 9.1 concern with the datasheet. This shows that the zenar diode will not conduct until it will reach towards that breakdown voltage.

So manually we can easily find out the current

This is the total current through the circuit.

Explanation of components of DC Power Supply

AC supply: this will give proper 230 volts AC at the input.

Transformer: this is used to step down the AC volts because the circuit is unable to bear 230 AC volts. This will step down into 9 volts AC.

We are required 12 volts at the output of the transformer. Then according to that situation we will set the required number of turns at the primary and secondary side of the transformer. Then according to that we can easily get the step down voltage of 12 volts.

Rectifier

This will convert the AC volts into DC volts. In that circuit 4 diodes are forming a bridge. Like structure. This is the main circuit that will convert AC into DC.

Capacitors

There are two 470 uF, 0.1u capacitors are used. These capacitors are used to smooth the DC volts. These capacitors are attached after the rectifier.

LM7809

This is also called voltage regulator. The code 7809 shows that it can easily able to regulate up to 9 volts. If the voltage regular contain 7805 code then the output voltage will be 5 volts. For this scenario there is need to obtain 9 volts at the output so 7809 voltage regulator will be used.

Resistor

The 1K resistor will be used. This will help to prevent the circuit from any arbitrary current.

Zener diode

Only one Zener diode will be used in that circuit. It will be acting like a voltage regulator for a next circuit.

Schematics of DC Power Supply

Zenar diode of DC Power Supply

According to the characteristics of Zenar diode it will allow the current to pass through both ways. This is also known as two way street. It is also like a normal diode that will allow the current in opposite direction when it will reach towards the breakdown voltage. At that stage the zenar diode will start operating.

For that circuit the zenar diode is acting as a voltage regulator. Through attaching this we are able to obtain required output voltage. We are obtaining 9 volts at the output.

From the starting we have attach the oscilloscope after and before the transformer output. Then its waveform will be like this

Figure 1: Transformer input and output results :

The arrow showing that it is 230 AC volts

This will show the 12 Volt AC volts after the secondary side of the transformer.

Figure 2: Input and output results

Figure 3: Input simulation

For getting the 12 volts AC at the secondary side of the transformer set the value of primary and secondary side of the transformer as 19.166:1 this rating will provide the value of transformer as 12 volts. Then after this there is full wave rectifier. The main aim of this bridge is to convert the AC voltage into DC. The output waveform after rectification will be like this

Figure 4: waveform after the rectifier

In the next step apply the zenar diode and set its breakdown voltage at 9.04 volts. And apply the capacitor of 7.12mF. This will give 9 volts at the output of the circuit.

Figure 7: simulation results with zenar diode

LM7809

The voltage regulation can be done through the help of LM7809. This will give you exact 9 DC volts at the output. These voltages are completely stable at the output. This circuit is almost same like the zenar diode voltage regulation. But in that circuit we are using LM7809 IC instead of that diode for obtaining the required output. This component has many other ICs like LM7805, LM7812 or LM78XX. In that IC code the number 78 means there is positive output in volts and 05, 09, 12 means it will deliver regular voltages at the output, 05 means that there will be 5 volts at the output. We are required 9 volts at the output that is the reason why we use this IC.

In the start there is complete AC 230 volts with frequency 50 is given at the output of the circuit. The transformer has to step down these volts because 230 AC volts will harm the circuit. The transformer will receive the AC voltages at the input. For stepping down the voltage there is need to change the turns ratio. For getting the 12 volts value at the output of the transformer the ratio will be about 19.166:1. This will give 12 volts at the output of the transformer.

The next step is to convert the AC voltages into DC. For this we will use full wave ratification. In that phase there are about 4 diodes are attached in the form of bridge. The output waveform will be dc volts. But the main problem was that these voltages are not completely DC wave. It contains a lot of distortions. To put an end on these distortion we will add capacitors in the parallel. These capacitors will smooth the voltages but at the output of these capacitors there is still no 9 volts. After the capacitors there it can be seen that there is 15.2 volts are given. The reason is that capacitors are storing charge and releasing with time. Furthermore, there is LM7809 IC, this IC has three pins, one will take the input value and the other will give the output 9 volts DC. The third pin of this IC is ground. After this there is 835 resistor and 0.01 micro fared capacitor. Through this topology we can easily obtain 9 DC volts at the output.

Figure 8: Simulation results with LM7809

Simulations results of DC Power Supply

Simulation when LM7809 is used

Waveform after and before capacitor

Figure 11: Experimental current in millimetre

Oscilloscope results

The waveform in the oscilloscope is showing the results about the AC output of the transformer. The peak wave is showing that it is about 12 volts are coming after the transformer output.

Simulation when Zener diode is used

Experimental circuit of DC Power Supply

Explanation of waves

The sinusoidal wave is showing that it is the AC waveform that comes from the transformer output. The straight line is showing the DC line of 9 volts.

Pros and cons of Zenar diode and LM7809

Advantages

Zenar diode

Through the use of this diode the voltages are extremely maintained at the output.

This is one of the protective component of the circuit and it will protect it from unwanted currents.

LM7809

For regulating there is no need of external activation

It can be easily connected in series

Its value will never change by applying the load

More stable output can be obtained easily

Weakness

Zenar diode

In high voltages a lot of energy is completely wasted due to this zenar diode because of breakdown voltage.

Due to zenar diode the output voltage are not easily adjusted because of breakdown voltage.

LM7809

The voltages are regulated in more excessive way may damage the load

There is need of cooling system for the circuit

It contain 3 pins

Testing explanation

The input AC voltages are stepped down to 12 volts through testing. This is done by changing the number of coils. As n=230/20=11.5 volts. That is almost 12 volts. Then the value of capacitor is selected, when Zener diode is used. For obtaining the 9 volts at the output the value of capacitor is about 5.13 mF is used.

Conclusion of DC Power Supply

Summing up all the discussion from above it is concluded that through following these steps it is easy to make a 9 volt dc power supply. In that report a complete circuit of 9 volt DC supply is drawn on the software and its waveforms are explained.