Experiments with 741- Operational amplifier

Description: This versatile 741 operational amplifier module can be used for making a dark detector using an LDR, a photo transistor and a photo diode. The amplifier has been configured in inverting mode. It compares the change in voltage at pin 2 with the reference voltage at pin 3 and gives output at pin 6 accordingly.  A general calculation and working of similar project has been explained on buildcircuit.com.  CLICK HERE for the project.

Read the following articles to understand the working of operational amplifier:

OPERATIONAL AMPLIFIER

VOLTAGE DIVIDER RULE

DARK SENSOR AND HEAT SENSOR

REQUIRED COMPONENTS: 

• Resistors: 10k (2), 15k (2), 100k (1).
• IC: 741
• Variable resistor(preset/potentiometer): 1M (1).
• LED (1).
• LDR (1) or Photodiode (1) or Phototransistor (1).
• LED: Any color
• Mini breadboard
• Battery: 6V- 9V
• Wires

Project on mini breadbaord:

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Schematic:

WATCH THE FOLLOWING VIDEOS

In the following videos, you will see how we can make dark sensors using LDR, phototransistor and photodiode. Once you make the sensor using LDR, you just need to replace the LDR with photodiode and phototransistor. You don’t need to replace or add any other component.

LDR and 741: 

Phototransistor and 741: 

Photodiode and 741: 

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