How To Make H Bridge Motor Controller Using Power Transistors

In order to control an AC/DC motor using a microcontroller or µ-processor, we need something called a motor controller/driver. A motor controller generally serves as an intermediary between the motor and the microcontroller. Simply put, a motor driver/controller circuit controls the direction of the motor based on externally applied voltage signals. In today’s tutorial, we are going to go over a step by step procedure on how To Make H Bridge Motor Controller Using BD139 & BD140 Power Transistors

What is an H Bridge Motor Controller?

An H Bridge motor controller is an electronic circuit that allows a voltage to be applied across a load in any direction. It is fabricated by using four switching devices (transistors/MOSFETS). H-bridge circuits are frequently used in robotics and many other applications to allow DC motors to run forward & backward. H Bridge motor controller circuits are mostly used in different converters like DC – DC, DC – AC, AC – AC converters

Hardware Component

You will need the following parts to build this project:

S.No	Component	Value	Qty
1)	Power Transistor	BD139, BD140	4
2)	Pushbutton	–	2
3)	DC Motor	9V, 1000rpm	1
4)	Resistors	1K, 220 Ohms	6
5)	Soldering Iron	45W – 65W	1
6)	Soldering Wire with flux	–	1
7)	Veroboard	–	1
8)	DC Battery	9V	1
9)	Battery Clips	–	1
10)	Jumper Wires	–	As per need
11)	Plastic Fan Blades	–	1

BD139 Pinout

BD140 Pinout

Useful Steps

1) Solder together the collector terminals of the BD139 & BD140 into two separate pairs.

2) After that, Solder a 220 Ohm resistor on the base of each resistor.

3) Solder one end of the pushbutton with the 220 Ohms resistor with the base terminal of the BD139 & BD140 transistor and other with the emitter pin of the BD139 transistor.

4) Solder 1K resistor between the 220 Ohm resistance and the emitter terminal of the BD140 transistor.

5) Solder the +ve pin of the battery terminal with the BD140 emitter terminal and the -ve pin with BD139 emitter terminal.

6) Connect the DC Motor between the collector terminals of the BD139 & BD140 transistors.

7) Power up and test the circuit.

Circuit Diagram For H Bridge Motor Controller

Working Explanation

The working of this circuit is as following, When SW 1 is closed and SW 2 is opened transistor Q3 and Q2 are in operation, allowing current to flow from them. The DC motor connected across the collector output of the transistor bridge 1 and 2 starts rotating in clock wise direction.

When SW 1 is opened and SW 2 is closed transistor Q4 and Q1 are operational. Current start flowing through this path and the motor starts moving in the anti clock wise direction. If both the SW 1 and SW 2 are opened or closed to current path will be established and motor will not rotate. If any input is closed and enable is not at high potential than the circuit will not work.