Why would you want or need to modify your perfectly good servo? It turns out that servo motors are great little gear motors that can connect directly to a microcontroller without the need for a motor driver circuit. The problem is that servo motors are made to turn between 90 and 180 degrees, for turning the front wheels of a remote control car, turning a rudder, controlling ailerons, etc.
But we want to use these cheap high-torque motors to turn the wheels on our robot. This instructable will show you how to make your servo spin 360 degrees.
Why the TowerPro MG995? It's cheap and powerful. At 4.8 volts, the MG995 produces 138.9 oz/in of torque and spins 360 degrees in 1.2 seconds. The MG995's are all over eBay for just under ten dollars apiece. I might not use these to steer a $1,000 RC plane, but they are terrific for powering the drive wheels on your robot.
I highly recommend watching the YouTube video first so you have an overall view of what you will be doing in this project.
Step 1: Parts and tools
Parts and tools
MG 995 Servo
Two 2.2k ohm resistors
Needle-nose and diagonal pliers
Flat and phillips head screwdrivers
**Optional - for testing purposes
Arduino or microcontroller of your choice
3 jumper wires