Bi-directional DC Motor Control

This simple circuit lets you run a DC motor in clockwise or anti-clockwise direction and stop it using a single switch. It provides a constant voltage for proper operation of the motor. The glowing of D1 through D3 indicates that the motor is in stop, forward rotation and reverse conditions, respectively.

Timer IC2 is wired as a monostable multivibrator to avoid false triggering of the motor while pressing switch SW1. Its time period is approximately 500 milliseconds (ms).

Suppose, initially, the circuit is in reset condition with Q0 output of IC1 being high. Since Q1 and Q3 outputs of IC1 are low, the outputs of IC3 and IC4 are high and the motor doesn’t rotate. D1 glows to indicate that the motor is in stop condition.

When you momentarily press switch SW1, timer 555 (IC2) provides a pulse to decade counter CD4017 (IC1), which advances its output by one and its high state shifts from Q0 to Q1. When Q1 goes high, the output of IC4 at pin 3 goes low, so the motor starts running in clockwise (forward) direction. D2 glows to indicate that the motor is running in forward direction.

Now if you press SW1 again, the high output of IC1 shifts from Q1 to Q2. The low Q1 output of IC2 makes pin 3 of IC4 high and the motor doesn’t rotate. D1 glows (via diode D2) to indicate that the motor is in stop condition.

Pressing switch SW1 once again shifts the high output of IC1 from Q2 to Q3. The high Q3 output of IC1 makes pin 3 of IC3 low and the motor starts running in anti-clockwise (reverse) direction. D3 glows to indicate that the motor is running in reverse direction.

If you press SW1 again, the high output of IC1 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. D1 glows via diode D1 to indicate that the motor is in stop condition. Thereafter, the cycle repeats.

Schematic:

Final Assembly:

Components Required:
R1,            10kΩ  Resistor
R2,            47kΩ  Resistor
R3-R5,      330Ω (or 680) Resistor
R6-R7,      10kΩ  Resistor
IC1,           CD4017
IC2-IC4,   555 Timer
D1-D3,      LEDs
D4-D5,     1N4007 Diode
C1,           100nF Ceramic Capacitor
C2,           10uF/25v Electrolyte Capacitor
MT1,        DC Motor
SW1,        Push Button
B1,           9v Battery