upgrading from small motor
Let's say I have a motor control circuit that's too small. It could be the motor output of a Picaxe, the adafruit motorshield for arduino or a the innards of an old RC toy. The main thing is that it has two output wires, both capable of delivering positive and negative to make a motor turn both ways.
What if you want to use a bigger motor that needs more power? Below are three circuit diagrams
The first is just a representation of the existing circuit highlighting the old contraption in a red frame
The second diagram show a simple circuit connected to the motor output. This will allow a higher voltage to drive a bigger motor. The Darlington Power Transistor will act as a switch controlled by the old/small motor power, allowing the big battery power to connect to the big motor.. New circuitry framed in blue. I know this circuit works in theory, but it will only allow the motor to be controlled in one direction. So your robot will only move forward, not in reverse...
The third diagram has an even larger circuit framed in green. Will this make the big motor turn both ways? Thus mirroring the behaviour of the small motor?
THAT'S what I really wanna know. Any ideas anyone?