The electronic devices are very sensitive to the fluctuations in the power fed to them. This problem can be solved by using regulated power supply for them. This [[wysiwyg_imageupload::]]project about power supply circuit is equipped with an adjustable voltage regulator to adjust the output in accordance with the requirement. Adjustable voltage regulators have both line and load regulation which is better than standard fixed regulators. The circuit is made using following active and passive electronic components: 1. Bridge Rectifier2. Resistors3. Capacitors 4. Variable Resistors.5. Linear Voltage Regulator IC
Voltage regulator is a device which provides fix output voltage in spite of the variable input voltage supplied. It is a three terminal device. Voltage [[wysiwyg_imageupload::]]regulator basically comes in two different series: 78XX and 79XX. Voltage regulator under 78XX series are designed for positive inputs i.e. if while 79XX series are designed for negative inputs.
A simple circuit of variable power supply and charger is described here. It is useful when the main power supply is available or when there is no power supply.This circuit can be used for testing electronic projects at your work bench. It can be used to charge your mobile battery. It can be used as an emergency light. In this circuit you can take outputs by flipping the different switches according to your requirement. Engage switch S3 if you want a variable power supply as output. For variable power supply, we have used variable voltage regulator LM317whichis a 3 terminal adjustable positive voltage regulator. It will provide an output voltage in the range of 1.2V to 37V. For obtaining different voltages, adjust the variable resistor to see the output on the multimeter and set the required voltage. Range of power supply varies from 1.5V-12V.