LIGHT_ACTIVATED_MOTOR_DRIVE_CIRCUIT

Published:2009/7/20 2:38:00 Author:Jessie | From:SeekIC

The circuit is a basic light-activated on/off switch for the motor. A CMOS op amp (IC1) is used as a voltage comparator. The comparator monitors the levels of two input voltages and switches its out-put on or off, depending on which input voltage is greater. The input on pin 2 is set to a reference voltage of about half the supply voltage by R3 and R4. The input on pin 3 is connected to a voltage divider made up of a cadmium sulfide photocell (R1) and potentiometer R2. The resistance of a photocell changes depending upon the amount of light shining on it, so the intensity of light is indicated by the voltage on pin 3 of IC1. The light level at which the circuit turns on is adjusted by R2. When the voltage on pin 3 of IC1 is greater than that on pin 2, the output (pin 6) turns on. The output of IC1 drives Q1 directly. That transistor acts like a current amplifier for the op amp. The transistor switches the motor on and off.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/LIGHT_ACTIVATED_MOTOR_DRIVE_CIRCUIT.html

Print this Page | Comments | Reading(3)