Voltage regulators important in electronic system as it keep voltage steady if input or load changes.
IC LM317 is famous and it give 1.25V to 37V output by choosing resistors.
This is Simple Adjustable Power Supply Circuit with IC LM317
Circuit show how it work, how to build and formula for design.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistor | 240Ω 1/4 watt | 1 |
| Potentiometer 5k | 1 | |
| Capacitor | Ceramic 0.1µF | 1 |
| Ceramic 10µF | 1 | |
| Semiconductor | IC LM317 | 1 |
IC LM317 is small, useful and keep voltage steady and reliable.
Has 3 pins and uses VR1 and R1 to set voltage.
Input voltage goes up to 28V DC which is good for many projects.
Adjustment pin (Adj) change output voltage with VR1 and R1.
Output voltage (Vout) remains steady at pin 2.
C1 help circuit react fast and C2 keep output steady.
LM317 adjust itself to keep voltage steady using VR1 and R1.
Formulas with Calculations:
Formula for LM317 output voltage is:
Vout = 1.25V × (1 + R1/VR1) + (Iadj × R1)
where,
- Vout is the output voltage
- 1.25V is inside reference voltage
- VR1 and R1 is the resistors in voltage divider
- Iadj is the adjustment pin current.
How to Build:
To build a Simple Adjustable Power Supply Circuit with IC LM317 follow the below mentioned steps:
- Take all parts like in circuit diagram.
- Connect ADJ pin 1 of IC1 LM317 to join point of resistor VR1 and resistor R1.
- Connect OUTPUT pin 2 of IC1 to one side of resistor R1.
- Other side of R1 connect between ADJ pin and one side of VR1 pot and other side of VR1 goes to GND.
- Connect INPUT pin 3 of IC1 to one side of capacitor C1 and other side of C1 goes to GND.
- Connect capacitor C2 one side to pin 2 of IC1 and other side of C2 goes to GND.
- Connect INPUT pin 3 of IC1 to Vin power supply.
- Connect OUTPUT pin 2 of IC1 to Vout power supply.
Conclusion:
Simple Adjustable Power Supply Circuit with IC LM317 is useful and reliable project.
By changing resistor values we get different output voltages.
This is an easy circuit and we can use for battery charger, microcontroller power and for adjustable DC source.