Electronic Speed Controllers (ESC)

These are widely used to regulate the speed of motors in electric models. What do they do and how do they work?  The speed control generally plugs into the throttle channel of a 3 or more channel radio. It also has connections to the motor and to the battery that powers the motor. Nearly all speed controls offer a BEC (battery eliminator circuit) function which removes the need to also use the 4 cell battery to power the receiver. The power to the receiver is provided via the 3 wire lead that you have plugged into the throttle channel. Most speed controllers vary the speed of the motor by turning the power on and off at a varying frequency of ON and OFF times. The more the controller is ON for example, the more power reaches the motor. There are lots of different controllers on the market for different types of motors, current draw and number of cells. Controllers for Brushed motors will not work on Brushless motors and  98% of Brushelss controllers will not work on Brushed motors. To choose the right type of controller for your application you need to know how much current the motor will draw under maximum load and how many cells you will be using. Better speed controllers like Schulze, MGM Compro and Kontronik utilise more FETS to minimise resistance and operate at higher frequencies than the cheaper Chinese units. This means that more Volts reach the motor in a smoother more proportional manner, making your model easier to fly.
 
In general, its better to purchase an electronic speed controller with a slightly higher rating than what you require. Then in future, you can use it on bigger models. Make sure that you use brushless and brushed controllers with their corresponding motor types.