Variable DC Supply
Using this circuit you produce a variable DC power
supply for your other projects.
Apparatus
1. Transformer
(230/12 V)
2. 4
Diodes
3. Capacitors 1. C1
(3300uF)
2. C2 (0.1uF)
3. C3 (1uF)
4. Resistors
1. 240 ohm
2. Variable resistance
(you can take of any range that suits
your application)
5. Connecting Wires
Circuit Diagram:
Working:
The voltage is converted to 12 V ac through
transformer then it is converted to the dc supply by the diode bridge. The
capacitor C1 is used to smooth out the output waveform of the diode bridge. The
output at the diode bridge is pulsating DC .This cannot be directly used for
most of the applications. So we need to convert the output into the constant dc
supply.
For this purpose we are using a voltage regulating
IC (LM317).It is having three terminals Adjust, Input and Output. Connections
of it are shown in the figure. We are using the C2 capacitor to reduce the
noise .The Capacitor C3 is used to reduce the ripples in the final output.
The output Voltage can be determined by the
following formula:
Vout=1.25(1 + R2/R1)
Thus by keeping R2=720 and R1= 240 we get the output
voltage as 5V.
Thus if you keep going changing the value of the R2
you can get voltage upto 37 V .
For those who don’t know about IC LM317 . I will be
also adding a new page containing information about the components I am using
in the projects. Plz refer that.
If you have any doubts plz ask in the comments. :)
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