Mount Motor Upgrade
Why add motors?
One of the common upgrades done to mounts with manual controls is a motor upgrade. Out of the box these mounts don't come with any, so slewing to the desired target and tracking it all needs to be done manually. There is an official motor kit available, but it is rather expensive for just adding basic slewing and tracking. That is why the community has stepped in and modeled mounts to add stepper motors to this mount.
How does it work?
A basic control system for such amount consists of a motor (usually a stepper motor), a driver circuit to make the motor move the way you want it to and a controller (usually a microcontroller).
The motor
The reason why we don't want to use DC motors is because we cannot finely control the position of such motors. Stepper motors usually have two phases that allow you to move the motor a specific amount. Do note: with a stepper motor you cannot "set" a position, since there is no sensor. If the motor gets overloaded then it might not turn, but the controller cannot known that. Servo motors aren't very common in amateur astronomy, because they are expensive and in most cases they shouldn't be needed or wouldn't improve anything. Most of the time standard sized stepper motors are used, like NEMA 14 and NEMA 17. Most of the time they will have available in 1.8 degrees or 0.9 degrees per step.
The motor driver
We cannot directly connect a stepper motor to a controller. The GPIO (General Purpose Input Output) pins cannot handle the current or voltage required to make a stepper motor turn. That is why motor drivers are used, in the case of stepper motor we use stepper motor drivers. These chips or breakout boards take low voltage logic signals and can be connected straight to a stepper motor. Most new stepper motor drivers have a special features called microstepping, where it can divide whole steps into smaller steppers, allowing you to increase the resolution of a motor. 2x, 4x, 8x and 16x is available on most drivers, but they can also be found with 32x, 64x, 128x and even 256x microstepping.
Almost all drivers have STEP and DIR pins. They are very simple, the motor takes one step when the STEP input changes, and the DIR input changes the direction. Newer drivers also have serial inputs that allow you to for example set a speed.
The (micro)controller
In many modern devices we find microcontrollers. These are little chips that can be programmed to do specific tasks. You can write programs for them just like you can for a computer, but in this we call it embedded programming and it is done on a much lower level. They are the ideal type of controller for telescopes because they are extremely cheap, low power and easy to integrate with other hardware. In the case of the mount controller we use the microcontroller as "calculator" to translate the coordinates of a celestial body to the angle of the telescope axis, control the motors drivers to make the mount slew to that celestial body and to track it.
OnStep
Good news! You can forget most of what you just read. A project called OnStep does most of the work for you. This software project allows you to connect your phone or computer and easily control your mount.