Soft-touch Bi-directional Motor Driver
  
 Alow component count soft- touch bi-directional motor driver can be constructed using two popular integrated
 circuits and a few other passive components. This circuit is designed for controlling speed and direction of
 micro DC motors generally used in electronic appliances such as video cassette rewinders, mini hand tools
 and toys etc. Heart of the circuit is a bi-directional motor driver IC BA6209UB. It has two input pins for
 direction control. It performs the bi-directional driving and braking operations using very few external parts.
 Decade counter CD4017B IC is used to control the logic inputs to the motor driver IC. When power switch S1
 is turned on, the circuit gets 12 volts DC and the decade counter (IC1) gets reset by the power-on-reset circuit
 formed by resistor R3 and capacitor C2. On reset, the Q0 output of IC1 goes high and rest of the circuit
 remains inactive. When switch S2 is pushed once momentarily, pin 14 of IC1 gets a positive going clock pulse
 and its Q1 output (pin 2) becomes high. As a consequence pin 5 of IC2 also becomes high and the motor
 starts rotating in forward direction, until switch S2 is again pushed to stop the motor. Capacitor C3 is used to
 suppress parasitic oscillations. When switch S2 is pushed for the third time, Q3 output (pin 7) of IC1 goes high
 which in turn makes pin 6 of IC2 high. This results in reverse rotation of the motor. Next (fourth) push of switch
 S2 stops the motor and it resets the decade counter simultaneously. One minor adjustment is required for
 safe operation of the circuit. For this, after assembling the circuit, set preset VR1 in its mechanical centre
 position and connect a digital multimeter (DMM) across the motor terminals. Now switch on the motor in
 forward direction and adjust the wiper of VR1 (towards ground rail) so that the DMM reads 6.0V DC  1 per
 cent. Functional truth table of motor controller IC BA6209UB is given. 