Introduction
When we talk about the voltage regulator, we know that they provide regulated output voltage, usually used in embedded systems. Basically, a regulated power supply enables the output not to make any changes if the changes would be made in input signals. In simpler words, you can say that the output is stable and independent of the input. Now coming towards the variable supply, these are the circuits that allow to vary or change the output voltage within the defined range. To understand this circuit, in this tutorial, we are going to “Variable Regulated Power Supply IC LM317”
To make this circuit our main component is the adjustable voltage regulator IC LM317 having an output voltage range from 1.2V to 37V. However, this circuit output voltage would have a range of 30V. The Ic has thermal shutdown protection which makes it more promising.
Hardware Components
The following components are required to make Variable Power Supply Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Stepdown transformer | 230V to 25V-500mA | 1 |
| 2. | IC | LM317 | 1 |
| 3. | Diode | 1N4001 | 5 |
| 4. | Variable Resistor | 10K | 1 |
| 5. | Capacitor | 1000uF, 0.1uF, 10uF | 1,1,1 |
| 6. | Resistor | 18K, 220R, 1K, 100R | 1 |
LM317 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM317
Variable Power Supply Circuit
Working Explanation
This Variable Regulated Power Supply uses the first stage of the transformer where it steps down the voltage to 25 V. After that, the rectifier circuit that is made from diodes converts. It converts both input polarities into pulsating DC. abut, it still has ripples in it which get filtered by the capacitor C3 wired in the circuit. The output is given to the input pin of IC. This IC has an ADJ pin where we connected the potentiometer. This potentiometer is used to vary the output voltage from 1 to 30 V. Hence, the output is taken across the capacitor C1.
Application and Uses
- Various electronic gadgets and devices use this to adjust the voltages.
