plz i need variable dc power supply using ic lm317 project report and seminar report on lm317ic
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Variable DC power supply is one of the projects that each student of the electronics should build. Build your own power supply is fun and use it throughout your building projects is the reward of your success. This project uses a transformer to reduce the incoming AC voltage to 12.5V AC.
This circuit is designed for 240VAC input voltage. If 110VAC is necessary, a power transformer 110 / 12.5 should be used. Buck of AC voltage is then rectified by a diode bridge. The rectified DC voltage is smoothed by means of an electrolytic capacitor 2 200uF / 50V.
The rectified voltage is then introduced into a regulator LM317 adjustable voltage input. This three-Terminal voltage regulator has an operating range of output voltage of 1, 2V to 37V DC with a current of maximum load of 1, 5A. One of the manufacturers of this device is Fairchild Semiconductor.
This regulator has an internal short-circuit current limiting protection to know if you short the output of the regulator, it will be stopped automatically. Once the short circuit has been removed, it will return to its normal operating mode. The internal thermal overload protection will also ensure that it stops when the operating temperature becomes too hot.
If food is engineered to provide a DC 12V, use an R2 = 2200 ohms. A radiator must also be used to ensure that the heat generated in LM317 can be dissipated into the environment. Fuse F1 is used to ensure that if the over-current occurs, it disconnects from the primary circuit of the power supply. The capacitor C1 is used to bypass the high-frequency content due to transitional or other electrical interference.
An additional diode D1 is used to protect the LM317 where the output voltage is greater than the first during the switching off of the circuit. Make sure that you use the power cables which is thick enough to withstand the current. A gauge suggested at least AWG # 20 to leads must be used. You will also need to have housing to accommodate the printed circuit board. There are many standard boxes you can buy from electronic supply stores.