05-04-2012, 12:46 PM
LM 317 REGULATED POWER SUPPLY
36658565-Regulated-Power-Supply-Doc.doc (Size: 375.5 KB / Downloads: 42)
INTRODUCTION
The LM 317 series is adjustable to three terminal positive voltage regulators. The different grades of regulators in the series are available with output voltage of 1.2 to 57 volts and output current from 0.1 to 1.5 ampere.
The LM 317 series regulators are available in standard transmitter packages that are easily mounted and handled. The three terminals Vin, Vout, adjustable.
The LM 317 develops a nominal 1.25 volt referred to as reference voltage between the output and the adjustment terminal. The maximum value of adjustable pin current is 100µA.
It is highly efficient in protecting circuits that are complex and complicated. That is why LM 317 circuit is highly useful.
WORKING PRINCIPLE:
THIS IS A SIMPLE, BUT LOW-RIPPLE POWER SUPPLY AND AN EXCELLENT PROJECT IF YOU'RE STARTING OUT IN ELECTRONICS. IT WILL SUIT YOUR NEEDS FOR MOST OF YOUR BENCH TESTING AND PROTOTYPE APPLICATIONS.
The output is adjustable from 1.2 volts to about 30 volts. Maximum current is about 1.5 amps which is also sufficient for most of your tinkering. It is relatively easy to build and can be pretty cheap if you have some or all the required parts. A printed circuit board is not included and I'm not planning on adding one since the whole thing can easily be build on perforated or Vero board. Or buy one of Radio Shack/Tandy's experimenters’ boards (#276-150). Suit yourself. The meter and the transformer are the money suckers, but if you can scrounge them up from somewhere it will reduce the cost significantly. BR1 is a full-wave bridge rectifier. The two '~' denotes 'AC' and are connected to the 25vac output coming from the transformer.