2B-VARIABLE REGULATED POWER SUPPLY
This project is a multipurpose project which can be used by anybody including electronic hobbyst and TV technician . Keeping in view the cost of battery and necessity of
eliminators, this project has been developed . Its output is regulated and variable. As such any amount of voltage can be obtained by adjusting the control.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and tested O.K. in our TV Engineers Te
chnical Lab. The components and PCB used in the projects published in our books are available for sale at resonable price.
This project is very simple and economical. The working of the project depends on the working of regulator IC LM317. The internal configuration of the IC consists of transistors. The IC is a three terminal IC and the center terminal of the IC is connected to the base of its internal transistor. As per the principle of transistor, by varying the base voltage , the regulated DC voltage is obtained from the other pin. The unregualted DC voltage available from the bridge rectifier is first applied to pin no 1 of the IC. The regulated DC supply is obtained from Pin no 3 of the IC. The base biasing is given from pin no 3 through a pre-set and res
istance. By varying the preset, the base biasing can be varied. Through the variation of the base voltage, variable DC output is obtained.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
*Check polarity of voltmeter and ameter while assembling.
*It is neccessory to used IC LM317 with heat sink.
*Check polarity of electrolytic capacitor while mounting on PCB otherwise reverse connection may damage it.
*First of all check all the components as per circuit.
*Check the polarity [ Anode & Cathode] of Diodes before fitting.
IC LM 317 = 1
100MFD/25V = 1
22MFD/25V = 1
1000MFD/25V = 1
10K PF = 1
100E = 1
PRESET 1K= 1