Project Report-Electronics-Lab Report, Exercises of Electronics

Download Project Report-Electronics-Lab Report and more Exercises Electronics in PDF only on Docsity! 1 | P a g e Objective: The objective of this project is to understand the working of LDRs and Op-amps, which are a major part of the sun-seeker circuit. Also, to design and combine, the mechanical part and the circuit. Sun-seeker: A sun-seeker is a light/dark sensor circuit. It has a panel that faces the sun or any other light source, due to the light change on the LDRs (Light Dependent Resistors) in the network. Equipment: For Circuit: Variable Resistors 2 LDRs 2 10kΩ Resistors 5 15kΩ Resistor 1 1kΩ Resistors 7 IC LM741 3 Transistor D313 4 DC Motor 1 Bread Board Vero Board Digital Multimeter Trainer Board Connecting Wires For Mechanical Module: Gears or Pulleys Board docsity.com 2 | P a g e Circuit: Ā A 3 docsity.com 5 | P a g e Hence both the ‘A’ and ‘Ā’ terminals of the motor will give zero, and the transistors will remain OFF, since inputs at their base are all zero. Therefore the motor will not turn on when the both the LDRs have same light intensity on them. Light Intensity on 1st LDR is greater than 2nd LDR: When the light intensity on 1st LDR is greater than the 2nd LDR, its resistance will be less than the 2nd LDR. So most of the input at its end will be grounded because of LDR’s low resistance and a little amount of current will enter the –ve input terminal of the 1st OP- Amp. On the other hand the other LDR’s high resistance will not allow the input current at its end to ground. So the input at +ve input terminal of the Op-Amp will be higher than the –ve input terminal and hence the output of the 1st Op-Amp will be positive. Therefore the value at ‘A’ will be positive and value at ‘Ā’ will be negative. So the transistors with ‘A’ terminal at their bases will turn ON and the current will flow in the indicated direction. Light Intensity on 2nd LDR is greater than 1st LDR: When the light intensity on 2nd LDR is greater than the 1st LDR, its resistance will be less than the1st LDR. So most of the input at its end will be grounded because of LDR’s low resistance and a little amount of current will enter the +ve input terminal of the 1st OP- Amp. On the other hand the other LDR’s high resistance will not allow the input current at its end to ground. So the input at -ve input terminal of the Op-Amp will be higher than the +ve input terminal and hence the output of the 1st Op-Amp will be negative. Therefore the value at ‘Ā’ will be positive and value at ‘A’ will be negative. So the transistors with ‘Ā’ terminal at their bases will turn ON and the current will flow in the indicated direction. Result: The motor is moving the panel in the direction of light, shaded on the LDR pair. docsity.com 6 | P a g e Appendix Variable Resistors: Variable resistors consist of a resistance track with connections at both ends and a wiper which moves along the track as you turn the spindle. Variable resistors are often called potentiometers in books and catalogues. LDR: An LDR is a Light Dependent Resistor. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops dramatically. When the light level is low the resistance of the LDR is high. Effect of light on current due to LDR IC LM741: The LM741 is a high performance monolithic operational amplifier constructed on a single silicon chip. It is intended for a wide range of analog applications: Summing amplifier Voltage follower Standard Variable Resistor docsity.com 7 | P a g e Integrator Active filter Function generator Transistor D313: The NPN transistor D313 is designed for use in general purpose amplifier and switching applications. DC Motor: Dc motors are normally used as prime movers in computers, numerically controlled machinery, or other applications where starts and stops are made quickly and accurately. DC motors have lightweight, low-inertia armatures that respond quickly to excitation- voltage changes. docsity.com