The following is a brief explanation of Schottky diodes and their use with electronic speed controls.

A Schottky diode is a special type of diode with a very low forward-voltage drop. When current flows through a diode, it has some internal resistance to that current flow, which causes a small voltage drop across the diode terminals. A normal diode has between 0.7-1.7 volt drops, while a Schottky diode voltage drop is between approximately 0.15-0.45 – this lower voltage drop translates into higher system efficiency.

At partial throttle, a speed control switches the battery power to full-on and full-off at varying duty cycles. The ratio of the duty cycle determines the throttle setting – for example: 50% on to 50% off is 1/2 throttle. The Schottky diode is used to carrying the re-circulating current from the motor during the 'off-time' while the speed control is at partial throttle.

Similarly, the motor in a car is like a big inductor. During the off-time at partial throttle, the motor will not allow the current to just stop. Instead, the voltage across the motor will reverse, and current will flow through the Schottky diode. If no diode is present, the current will flow through a parasitic diode built into the brake transistors. The current flows through the Schottky diode before it will flow through the brake transistor because the forward voltage drop of a Schottky diode is less than the brake transistor diode (this is why Schottky diodes are used and not other types of power diodes).

For the highest efficiency, during the off-time while the motor continues to flow current, the voltage should ideally be as close to zero as possible. One reason Novak uses an external Schottky diode is because the closer the diode is to the motor, the lower the voltage drop during this period. This is due to the voltage drop through the wires back to the speed control. This will also reduce some radio noise due to the current spike not having to travel a long distance.

Speed controls like the Hammer, Racer, Tempest, Atom and the Cyclone are racing speed controls. For the ultimate performance, an external Schottky diode is used (The Cyclone has one built-in also.). As a result, the speed control is smaller. Also, as a convenience to the newcomer, Novak's sport models have it built-in.

Another reason Novak uses an external Schottky diode is to prevent the brake transistors from overheating and losing brake power. When a Schottky diode is built into an ESC, it is positioned next to the brake transistor. As the Schottky heats up, it heats the brake transistor and consequently loses braking power (the on-resistance increases).

The hotter the motor that is used (i.e. the lower the number of turns), the higher the current that flows through the Schottky diode. In some cases, two diodes connected parallel must be used (connect both striped ends to motor positive and both non-striped ends to motor negative).