Hi , today we will start with power source

We'll talk about how the make a circuit give us a specific voltage , Using simple tools .. Let us follow the explanation

Someone tell me that he has Adaptor gets through the specified voltage.

You can adjust the voltage here 3 or 4.5 or 7.5 or 6 or 9 or 12 volts.

there is a connector can be fitted with a number of home devices.

Today,we will learn how to make of a circuit give us a specific voltage

But first we must understand some of the fundamentals that we will see together.

Electricity that feeds the house is AC while Aladaptor gives us a DC.

We need a transfer from AC to DC.

Before that we need to reduce the voltage from 220 volts to 12 volts

## Step 1: The Transformer

The piece that will be to reduce the voltage is the electrical transformer.

Note that group of transformers in various size and power.

All that transformers may be graduated 12 volts,But this bigger one deliver electric current more than the smaller one, and so on.

You should choose the appropriate transformer for the device to be used.

In our project we will need a small transformer.

Electrical circuit that we will proceed to implementation, we will need only half the AMP

Here we will not go to the theory of the work of the transformer.the transformer works on the principle of electromagnetic induction.

## Step 2: Making Bridge Rectifier

We use bridge rectifier to convert from AC to DC.

You can use Diode with number 4001 .... 4007.

Silver line on the diode indicates the cathode terminal.

Link the pair cathode together .

Connect anodes for a couple diodes.

Then we connect the parties together.

Now we have a bridge rectifier.

we can use only one piece bridge rectifier instead of 4 diodes.

## Step 3: Merge the Rectifier Circuit With Regulation Circuit.

we merge the rectifier circuit with regulation circuit.

To filter the current and smooth it we use a capacitor 1000 micro Farad.

## Step 4: Signal Bulb

There it can be included to improve the circuit , a signal bulb

Bulb signal consists of a LED with resistance attached after the rectifier circuit.

To calculate the value of the resistance

The potential difference between the positive and the negative is a 9-volt

The voltage on the LED difference is 3 volts

Count the potential difference on the resistance by subtracting 9 minus 3 equals 6 V

The current intensity of the appropriate to feed the LED is 20 m Amp.

Application in Ohm's Law.

Resistance equal to the value of 300 ohms.

The closest value is 330 ohm find them.

Resistance can be placed above or below the LED.

## Step 5:

If you want to be a regulate the voltage out to 5-volt, regulator will use 7805

We can change the value of the transformer and change the regulator value for desired voltage.

We will use the transformer 15 volts or 24 volts and regulator 7812

Note that the inside voltage higher than the outside voltage by 2 or 3 volts

It is better to use a transformer with power bit higher than the power of the circuit.

For example, I have need voltage came out 5 volts, used a 9-volt transformer gives.

It's simple and easy circuit