legendtronics

have u ever wonder,how we can control robots to move right left straight  back.with out using steering in bots. i'll show u how we can control the direction of the bots .first we need to know abt h-brige.lets do that.

H-bridge:

As you can see in the image, the circuit has four switches S1, S2, S3 and S4. Turning these switches ON and OFF can drive a motor in different ways.

1. Turning on Switches S1 and S2 makes the motor rotate clockwise
2. Turning on Switches S2 and S3 makes the motor rotate anti-clockwise

1. Turning on Switches S1 and S2 will stop the motor (Brakes)
2. Turning off all the switches gives the motor a free wheel drive
3. Lastly turning on S1& S3 at the same time or S2 & S4 at the same time shorts your entire circuit. So, do not attempt this

• HOW TO CONSTRUCT H-bridges for DC motors:

1. type 1:-(4 inputs to control 1 motor)

H-bridges can be built from scratch using relays, mosfets, field effect transistors (FET), bi-polar junction transistors (BJT), etc. But if your current requirement is not too high and all you need is a single package which does the job of driving a small DC motor in two directions, then all you need is a L293D IC

A,B,C,D can be connected to micro controller and we can control the motors according to the program.
or
simple push switch connected between pt A and gnd...pt B and gnd ...similarly rest of the pt .by pushing the switches we can control the direction of the motor`

2.   type 2:-( 2 inputs to control 1 motor)

just by two switches we can control clock wise and anticlockwise rotation of the motors

3.    type 3:-( 4 inputs to control 2 motor)

Construction using l293d ic (4 inputs controlling 2 motors) :

how to control servo motors: