Every electronics circuit needs a power supply to work, so this post is dedicated to know,how can we construct our own power supply with great ease for varying uses,at low cost and eliminate the use of batteries and adapters.
Here we should convert 220V A.C mains to required D.C voltage,for that follow these sequence of steps:
step1: A transformer converts 220V A.C in to 12V A.C(based on transformer u choose),please do remember that it just steps down the voltage level and nothing more than that. dont be in an illusion that it directly gives D.C.
step2: 12V A.C output of transformer is now rectified by using either full wave rectifier or bridge rectifier based on the tranformer we use.the 12V A.C is having positive and negative peak voltages.so the rectifier does the job of converting bidirectional voltages to unidirection.
step3: the unidirectional voltage peaks given out by the rectifier is now converted to D.C by using filter capacitors. A filter capacitor converts uniderectional wave forms to constant D.C voltages,this is possible by the property of charging and discharging of capacitor.The typical value of a filter capacitor can be 1000uF or 470uF.
step4: up to the step3 we are able to get a D.C. but D.C is unregulated.to regulate this we can use zener diodes or simply a voltage regulator IC.
the voltage output we need can be obtained by using voltage regulators IC s of LM 78XX series.
where XX can be 05,06,09,12...etc
7805 can give a constant output of 5V whatever may be the input supply
7806 can give a constant output of 6V whatever may be the input supply
7809 can give a constant output of 9V whatever may be the input supply
7812 can give a constant output of 12V whatever may be the input supply
hence by choosing XX we can get the required D.C output voltage.
The most important part of a powersupply is a transformer,
The transformer can be two types
1.center tapped(3 output terminals)
2.non center tapped(2 output terminals)
->If we are using a center tap transformer then it will be easy to use a full wave rectifier.
->If we are using a non center tap transformer then it will be easy to use a brigde rectifier.
Just follow this Circuits given below for each tyoe of transformers.
FOR CENTER TAP TRANSFORMER USE THE CIRCUIT BELOW:
FOR NON CENTER TAP TRANSFORMER USE THE CIRCUIT BELOW:
