Secret Diagram

This circuit can control the direction of a DC motor., It has many applications that are necessary to operate a motor in both directions, clockwise and counter-clockwise (forward and backward). One way to accomplish this is to start the engine in a circuit arrangement of transistors called H-bridge. H bridge is an electronic circuit which enables a voltage is applied across a load in either direction. This circuit is often used in robotics and other applications to allow DC motors to become bi-directional.

List of components

PARTS LIST
R1, R2, R3, R4 220Ω
R5, R6, R7, 1K Ohm
D1, D2, D3, D4 1N4001
D5, D6 LED
Q1, Q2 2SD313
Q3, Q4 2SB507
PB1, PB2 switch
M1 12V DC MOTOR

In this circuit usually PB1 and PB2 are open. Thus, the bases of the transistors are grounded. Hence Q3 and Q4 are turned on, Q1 and Q2 are turned off. The voltages at both terminals of the motor is the same and thus the engine is switched off. Similarly, when both PB1 and PB2 are "on" motor is turned off. The LEDs indicate the direction of motor rotation.