LM358 – HVS Technologies

HVS-4301.Measurement of Temperature using RTD.

hvsadmin — Thu, 08 Jan 2026 10:22:25 +0000

An RTD stands for “Resistance Temperature Detector” and it is a sensor whose resistance changes when its temperature changes and it is used to measure temperature. The RTD’s resistance increases linearly when the temperature increases. Many RTDs are called wire wound.

This project aims to design a temperature measurement system using the DS18B20 temperature sensor, a relay, LM358 comparator, a fan, and a potentiometer. The DS18B20 sensor provides accurate digital temperature readings, which are compared against a user-defined setpoint using the LM358 comparator. When the measured temperature exceeds the setpoint, the comparator triggers the relay, activating the fan to cool the environment. The potentiometer allows for easy adjustment of the setpoint temperature. This system provides a simple yet effective way to regulate temperature in various applications, such as climate control in enclosed spaces or electronic devices.

The main objectives of the project are:

Design a RTD (Resistance Temperature Detector) system.
Continuous monitoring of temperature.
Automatic controlling of FAN.

The major building blocks of this project are:

Regulated power supply.
Comparator
DS18B20 temperature sensor.
Relay
POT
Fan

Regulated power supply:

Block Diagram:

video:

HVS-4524–SMART ALARM USING MOTION SENSOR USING LM358 COMPARATOR

hvsadmin — Wed, 07 Jan 2026 11:33:03 +0000

Smart alarm system designed to detect and alert users to the presence of motion in a given environment. The system integrates a LM358 comparator, a Passive Infrared (PIR) sensor, and a buzzer to achieve robust motion detection and notification capabilities. The heart of the system lies in the LM358 comparator, a versatile integrated circuit known for its precision and reliability in comparing analog signals. The comparator circuit is employed to analyze the output signal from the PIR sensor, which detects infrared radiation emitted by moving objects within its detection range. Upon sensing motion, the PIR sensor generates an electrical signal proportional to the detected movement. The LM358 comparator processes the signal from the PIR sensor, comparing it against a predetermined threshold voltage. When the signal exceeds this threshold, indicative of significant motion, the comparator triggers an alarm activation sequence. The alarm activation sequence initiates the activation of a buzzer, serving as an audible alert mechanism to notify users of the detected motion. The buzzer emits a distinctive sound, drawing immediate attention to the presence of potential intruders or unauthorized activity.

This smart alarm system offers a cost-effective and reliable solution for enhancing security in various settings, including homes, offices, and commercial establishments. Its utilization of the LM358 comparator, PIR sensor, and buzzer ensures efficient motion detection and timely notification, contributing to the overall safety and peace of mind of users.

Features of proposed system are:

It is very cheap and affordable.
It is efficient and portable that means we can place this circuit at any place easily.
Very easy to use.
Maintenance cost is low.

The project focuses on the following areas:

Characteristics of PIR sensor.
High voltage device controlling.
Buzzer working technique.

The major building blocks of this project are:

Regulated power supply with voltage regulator.
LM358 Comparator
Passive Infra Red Sensor (PIR).
Buzzer

Regulated power supply:

Block diagram:

video:

HVS-1000. Automatic Power failure Indication.

hvsadmin — Fri, 05 Dec 2025 10:01:18 +0000

The aim of the project is to construct an automated power failure alerting system using buzzer. The system is capable of detecting the failure of power and alerts the user through buzzer alarm system.

The project consists of a comparator. Supply voltage through Optocoupler is fed to the comparator. The comparator continuously monitors the supply voltage and automatically horns a buzzer connected to it, if supply is not present.

The features of the project are:

Alerts regarding power failure through buzzer.
Reference voltage can be adjusted using POT.

The major building blocks of this system are:

Regulated Power Supply.
Optocoupler
Buzzer with driver.
Comparator.

Regulated Power Supply:

Block Diagram:

video:

HVS-4557. Metal detector Using LM358.

hvsadmin — Mon, 06 Oct 2025 11:54:37 +0000

The metal detector project utilizes an LM358 operational amplifier and a metal detection sensor to create an efficient and responsive metal detection system. When the metal detector sensor identifies the presence of metal, the LM358 amplifies the signal, triggering a connected buzzer to emit a sound. This project demonstrates a straightforward yet effective approach to metal detection, offering applications in security, treasure hunting, and metal identification in various environments. The integration of the LM358 ensures reliable signal processing, while the buzzer provides immediate audible feedback upon detection, enhancing usability and response time.

OBJECTIVES:

Detect the presence of metal objects using a metal detection sensor integrated with an LM358 operational amplifier.
Amplify the detected signal reliably with the LM358 to ensure accurate metal detection.
Trigger a buzzer to emit an audible alert when metal is detected, providing immediate feedback.
Develop a simple and cost-effective metal detection system for applications in security, treasure hunting, and industrial metal identification.

THE MAJOR BUILDING BLOCKS FOR THIS PROJECT:

LM 358.
Metal detector sensor.
RPS.
Buzzer.

video: