Adjustable Voltage Regulator Circuit Using LM338

DC Voltage Source is Essential for every Electronic Circuits. Many Electronic Device Requires Regulated Constant Ripple free DC supply. Here we have designed Adjustable Voltage Regulator using LM338. To Provide Regulated DC output between 1.2 V to 32 V from 1.5 V – 35 V Input Unregulated DC supply.




IC LM338 from Texas Instruments is a Adjustable 3 Terminal Positive Voltage Regulator and it is capable of supplying in excess of 5 Amps over a 1.2V to 32V output Range. It Requires only two Resistors for its operation. Here we have using Variable Resistor to get desired output voltage.

Vout = 1.25V (1+R2/R1) + Iadj R2

Circuit Diagram

Components Required (BOM)

1C110µF/25VCP_Radial_D4.0mm_P2.00mm1
2C24.7µF/25VCP_Radial_D4.0mm_P2.00mm1
3R1120ΩR_Axial_DIN0204_L3.6mm_D1.6mm_P5.08mm_Horizontal1
4D1, D21N4007D_DO-41_SOD81_P10.16mm_Horizontal2
5U1LM338TO-220-3_Vertical1
6RV11KΩPotentiometer_Bourns_3266Y_Vertical1
7J1, J2Screw_Ter_01x02JWT_A3963_1x02_P3.96mm_Vertical2

Construction & Working

Main Element For this Adjustable Voltage Regulator is IC LM338, and Input pin 3 is directly connected to the Vin Positive terminal and Vout pin 2 is directly connected to the output screw terminal. Adjust pin 1 is connected to Gnd through Variable Resistor RV1.

By changing the Value of R1 and RV1 we can Change the Regulated output Voltage from LM338. C1 and C2 Capacitors are performing filter operation and D1, D2 Used as a Reverse protection Elements. Refer datasheet for more information.

Printed Circuit Board

Adjustable Voltage Regulator Using LM338 PCB Gerber files.

Interactive Board Viewer

     




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