Voltage Regulator: 5–24 V Input, Fixed 24 V Output

Overview

The voltage regulator is a board designed in 2015. It converts an input voltage of 5 to 24 V into a fixed 24 V output. Because the input can be lower than 24 V, the board uses an adjustable step-up (boost) converter built around an LM2577 IC, which raises the voltage. Three LEDs on the board show the value of the input voltage.

How it works

After the board is connected, the input voltage is checked first, and then, according to it, the output is regulated to 24 V. The LM2577 is the adjustable (ADJ) version, and the output is set precisely with the multiturn trimmer P1: turning it fixes the output at 24 V.

The three LEDs show the input voltage, so you can see the state of the input right where the board is mounted.

Specifications

• Input supply: 5 to 24 V

• Fixed output: 24 V

• Three LEDs to show the input voltage value

• Output adjusted with a multiturn trimmer (P1)

• 2 A fuse on the board

Hardware design

I designed the board, and it sits inside a plastic DIN-rail enclosure. The heart of the circuit is an LM2577 IC on a heatsink, which forms a step-up converter together with the inductor L1. A 7812 regulator (also on a heatsink), an LM324 in a socket, three display LEDs, a 2 A fuse and the input and output screw terminals make up the rest of the board.

The pictures below show the built board, the PCB layout and its 3D view.

Result

A small, simple board that makes a fixed 24 V output from a 5 to 24 V input and also shows the input value with three LEDs.