We learned earlier about all components we are going to use in making 5V power supply like transformer, bridge rectifier, capacitor, voltage regulator 7805. Now let’ see how to create a 5 V power supply
5V POWER SUPPLY
This is the circuit we want to make for 5 V power supply, but before making this let understand each part and working in steps below

TRANSFORMER 5V 2A
Transformer is an electrical device. It converts alternating current (AC) from one voltage to another without change in frequency. Transformers are of two types one is step up and other is step down.
We are using step down transformer, Select transformer of rating “5 V, 2 A” which help us to step down the voltage from 230 V AC to 5 V DC
BRIDGE RECTIFIER
Rectifier is a device which converts alternating current (AC) into direct current (DC). The component used to convert AC signal to DC signal we know it very well! Yes your guess is right, Diode.
Then use a bridge rectifier which converts AC signal to DC signal. But you can see this is not a proper DC signal.
ELECTROLYTIC CAPACITOR
A capacitor is a passive two-terminal electronic component that temporarily stores electrical energy. This improves battery life as well. Capacitor is also used for filtration of signals.
Next use an electrolytic capacitor “C1” of 470 uF, to filter signal, which makes this output curve smoother somehow like this.
CERAMIC CAPACITOR
Then the ceramic capacitor “C2” of 0.01uF is used to make the curve more smoother
VOLTAGE REGULATOR 7805
Voltage Regulator ICs are designed to maintain a constant voltage level. When a consistent, steady, stable voltage is needed, then voltage regulator is the preferred device. Voltage regulator 7805 gives 5 V at output.
Then we are using voltage regulator 7805 for constant voltage of 5V
AGAIN CERAMIC CAPACITOR
Then again we are using ceramic capacitor “C3” of 0.01 uF which makes it almost perfect DC signal with smooth curve as output. And we are able to get 5 V DC supply across the output terminals

NEXT YOU CAN START WITH ARDUINO
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LOGIC GATES USING TRANSISTOR
Nice. This diagram is really simple to understand.
Osam simple diagram and working