Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe

Performing Experiments With LM358

By Ashutosh Bhatt December 26, 2018

 

In this porject a circuit is made which can switch on the device when the light falls on it. For this I will use LM358 IC which is operational amplifier. I have made the circuit with LDR and few more components. But when I interchange the LDR with photodiode, phototransistor and transistor (L14F1) my circuit works well without changing any other components. Before understanding the circuit which I have developed, first let’s have a look on the components used in the circuit.

 


1. IC LM358– LM358 consists of two independent, high gain operational amplifiers in one package. Important feature of this IC is that we do not require independent power supply for working of each comparator for wide range of power supply. LM358 can be used as transducer amplifier, DC gain block etc. It has large dc voltage gain of 100dB. This IC can be operated on wide range of power supply from 3V to 32V for single power supply or from ±1.5V to ±16V for dual power supply and it also support large output voltage swing.

Pin configuration of IC is shown below-

Experiment with LM358

Fig. 1: Pin Configration of IC LM358

From the above figure you can see that operational amplifier has two inputs and one output in one independent LM358. Inputs are at pin 2 (negative pin) and 3 (positive pin), positive pin is used for positive feedback and negative pin is used for negative feedback. In ideal condition when no feedback is applied, gain of the operational amplifier should be infinite. When voltage at pin 2 is more than voltage at pin 3 it will raise the output towards the positive maximum voltage and a slight increase at negative pin compared to positive pin will lower the output towards the negative maximum. This feature of operational amplifier makes it suitable for the purpose of level detection.

2. LDR– LDR is a device whose sensitivity depends upon the intensity of light falling on it. The resistance of LDR decreases when intensity of light falling on it increases and vice versa (resistance increases when intensity of light falling on it decreases). In dark or in absence of light, LDR exhibits a resistance in the range of mega ohms, which decreases to few hundred ohms in presence of bright light.

Testing of LDR

You can check LDR with the help of multi-meter. Keep your multi-meter in ohm or resistor measurement region. When you cover the LDR its resistance will be very high and when you place it in light it decreases. This phenomenon indicates LDR is working correctly. We are utilizing this property of LDR to act at your LDR is working correctly. A sensor, since a varying voltage drop can be obtained with varying light.

3. Photodiode– Photodiodes convert light into current or voltage depending on its mode of operation. It is a PN junction or PIN structure. When a photon of sufficient energy strikes the diode it creates a free electron and a hole. Now the holes move towards the anode and electrons towards the cathode and a photocurrent is created.

Testing of Photodiode

You can check it with the help of multi-meter. Place you multi-meter in mV range. Now put the lead of multi-meter on leads of photodiode. Take the reading in dark as well as in presence of light. It shows deflection in reading in light and dark (in dark reading will be more) than your photodiode is working fine.

4. Phototransistor-Phototransistor is a light sensor similar to basic transistor but has transparent cover.Phototransistors provide a much better sensitivity than photodiode. Phototransistor has large base region than collector as compared to another transistor. They are made using diffusion or iron implantation method. Phototransistor works in active region. Generally its base is left open to sense the light falls on it. When light falls on its base it causes the electron hole pair to be generated. This phenomenon mainly occurs in reverse biased base collector junction, because of electric field electron hole pair move and provide the base current, causes electron to be injected into emitter.

Testing of Phototransistor

You can check the phototransistor with the help of multi-meter. Set your multi-meter in resistance measurement region than put leads of multi-meter on collector and emitter. Now cast some light on phototransistor and then remove the light. You can see the deflection in reading of multi-meter in light reading is small in comparison to dark. If this phenomenon is occurring than you can say your phototransistor is good. You can also use transistor L14F1 in place of phototransistor and the process to check is similar how we have checked phototransistor.

It is always a good practice to check components before using it.

Application of circuits

–    The circuit which I have made can be used as dark sensor or light sensor with very little modification. Therefore you use it as a security circuits like in intruder alarm, morning alarm, magic eye, luggage alarm or it will on the light in darkness or off the light in morning etc according to your application.

–    In the circuit diagram I have used a LED to show the output. You can also use relay in place of LED to connect buzzer or any external component like bulb, door bell etc.

Working of circuit

Working of circuits is very simple as we know LM358 compares the voltage applied at input pin and provide you the output. The voltage level which we want to detect is applied on either of the input pins and the voltage to be detected is applied on the other pin. For dark sensor circuits we are applying voltage on negative pin and voltage to be detected is applied on positive pin. Whenever input voltage applied on positive pin because of light which falls on LDR, photodiode and phototransistor slightly rises above the voltage on negative pin the output suddenly raises to the positive maximum and remains positive until the input voltage falls below the level to be detected. Transistor T1 is used to amplify the signals to drive the LED and resistor R1 is used as current limiter to protect LED and for light sensor circuit just reverse of above phenomenon is occurring.  You just change the LDR with photodiode and phototransistor and see circuit is working properly and sensitivity of circuit also increases. You can also connect different components and devices at the output, so try connecting your own device and see the output.

Experiment with LDR and LM358

Fig. 2: Prototype for Performing Experiments With LM358 on Breadboard

 

 

Circuit Diagrams

Experiment-with-LM348-using-LDR-2_0
Circuit-2_0_0


Filed Under: Electronic Projects

 

Next Article

← Previous Article
Next Article →

Questions related to this article?
👉Ask and discuss on EDAboard.com and Electro-Tech-Online.com forums.



Tell Us What You Think!! Cancel reply

You must be logged in to post a comment.

EE TECH TOOLBOX

“ee
Tech Toolbox: 5G Technology
This Tech Toolbox covers the basics of 5G technology plus a story about how engineers designed and built a prototype DSL router mostly from old cellphone parts. Download this first 5G/wired/wireless communications Tech Toolbox to learn more!

EE Learning Center

EE Learning Center
“engineers
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.

HAVE A QUESTION?

Have a technical question about an article or other engineering questions? Check out our engineering forums EDABoard.com and Electro-Tech-Online.com where you can get those questions asked and answered by your peers!


RSS EDABOARD.com Discussions

  • Right Half Plane Zero
  • Single ended measuring ports and balanced antenna
  • Thermal modelling of repetitive power pulse
  • Testing 5kW Grid Tied inverter over 200-253VAC
  • Resistor Selection for Amplifier Layout

RSS Electro-Tech-Online.com Discussions

  • Simple LED Analog Clock Idea
  • Fun with AI and swordfish basic
  • Is AI making embedded software developers more productive?
  • Can I make two inputs from one??
  • Behlke swich

Featured – LoRa/LoRaWan Series

  • What is the LoRaWAN network and how does it work?
  • Understanding LoRa architecture: nodes, gateways, and servers
  • Revolutionizing RF: LoRa applications and advantages
  • How to build a LoRa gateway using Raspberry Pi
  • How LoRa enables long-range communication
  • How communication works between two LoRa end-node devices

Recent Articles

  • RPi Python Programming 21: The SIM900A AT commands
  • RPi Python Programming 22: Calls & SMS using a SIM900A GSM-GPRS modem
  • RPi Python Programming 23: Interfacing a NEO-6MV2 GPS module with Raspberry Pi
  • RPi Python Programming 24: I2C explained
  • RPi Python Programming 25 – Synchronous serial communication in Raspberry Pi using I2C protocol

EE ENGINEERING TRAINING DAYS

engineering

Submit a Guest Post

submit a guest post
Engineers Garage
  • Analog IC TIps
  • Connector Tips
  • Battery Power Tips
  • DesignFast
  • EDABoard Forums
  • EE World Online
  • Electro-Tech-Online Forums
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • 5G Technology World
  • Subscribe to our newsletter
  • About Us
  • Contact Us
  • Advertise

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy

Search Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe