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DC Motor Control (using a single switch) 2011-05-16

SUMMARY

As a Hobby, I have devised this module and named it as “ DC Motor control using IC 7555. This simple circuit fabricated by me makes a DC motor to run in clockwise or anti-clockwise direction and stop it using a single switch. It provides a constant voltage for proper operation of the motor. LED 1 indicates that the motor is in stop condition. LED 2 indicates that the motor is rotating in Forward direction and LED 3 indicates that the motor is running in reverse direction.

Regarding the connection, I have wired the Timer IC1 as a monostable multivibrator to avoid false triggering of the motor, while pressing the switch S1. Its time period is approximately 500 milliseconds (ms).

Initially, the circuit is in reset condition with Q0 output of IC2 being high. Since Q1 and Q3 outputs of IC2 are low, the outputs of IC3 and IC4 are high and the motor doesn’t rotate. LED1 glows to indicate that the motor is in stop condition.

As I press the switch S1, the timer 555 (IC1) provides a pulse to decade counter CD4017 (IC2), which advances its output by one and its high state shifts from Q0 to Q1. When Q1 goes high, the output of IC3 at pin 3 goes low, so the motor starts running in clockwise (forward) direction. The forward rotation of the motor is indicated by Led 2.

Now when I press S1 again, the high output of IC2 shifts from Q1 to Q2. The low Q1 output of IC2 makes pin 3 of IC3 high and the motor doesn’t rotate. LED1glows (via diode D2) to indicate that the motor is in stop condition.

When the switch S1 is pressed once again, the high output of IC2 shifts from Q2 to Q3. The high Q3 output of IC2 makes pin 3 of IC4 low and the motor starts running in anti-clockwise (reverse) direction. LED3 glows to indicate that the motor is running in reverse direction.

As the switch (S1) is pressed again, the high output of IC2 shifts from Q3 to Q4. Since Q4 is connected to reset pin 15, it resets decade counter CD4017 and its Q0 output goes high, so the motor does not rotate. LED1 glows via diode D1 to indicate that the motor is in stop condition. Thereafter, the cycle repeats.

For not allowing the motor to run in reverse direction, I removed the timer IC4 along with resistors R5 and R7 and LED3 and connect ‘b’ terminal of the motor to +Vcc. Similarly if I do not want to operate the motor to run in forward direction, I removed timer IC3 along with resistors R4 and R6 and LED2 and connect ‘a’ terminal of the motor to +Vcc. I have utilized a 9V regulated power supply for a 9V DC motor.

By-
Arijit Kumar Bose
C/0 Dr. Debajyoti Bose
Abhirampur, PO Makdampur
Malda-732103, INDIA
Author
arijit18
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