MOSFET is an acronym – I’ll give you the whole phrase, so you know why they’re always called MOSFETs.. Metal Oxide Silicon Field Effect Transistor. MOSFETs are very near to perfect semiconductor switches, capable of Read More

All 4QDs controllers have a switching frequency of (around) 20 thousand times per second – 20kHz. This is high enough to give no whistle or whine from the motor but, more importantly, it means that Read More

Regenerative braking is a way of diverting the kinetic energy of a moving motor / vehicle back into the battery so that it re-charges the battery and provides a braking effect. Most of 4QDs controllers Read More

When the controller is not in use it needs to be deactivated. The ignition circuitry (fitted to all controllers) does this, so the controller draws no current and the throttle input will have no effect. Read More

When the controller is powered down (ignition turned off) but with the battery still connected, different controllers behave in different ways. There are, essentially, 3 possibilities: Open circuit Short circuit Diode Open circuit All semiconductor Read More

Some controllers can be used with either a 3 position toggle or rocker to give forward/off/reverse or with two push buttons to give ‘go forward’ and ‘go reverse’ control. The DNO and Pro series need Read More

If a controller includes regenerative braking, then there is a potential problem if a battery connection fails during braking. This can happen on a golf buggy if the batteries are not properly secured. If it Read More

Parking Brake Driver Regenerative braking relies on the voltage generated by the rotating armature to cause braking so it is speed dependent. If the speed is slow enough there is no effective braking, so the Read More

On some controller we can fit, at the factory, a ‘braking’ light driver. This braking light option replaces the standard parking brake driver. On road vehicles a brake light may be required. If the vehicle Read More

If a wire to the pot breaks various things can happen. If the full speed wire breaks, then the pot cannot select full speed so this is generally safe. If the output (wiper|) from the Read More

If the controller’s ignition is turned on while the throttle pot is not at zero the vehicle could accelerate to speed. High pot lockout [HPLO] prevents this by disabling the vehicle until the throttle returned Read More

If you inadvertently connect the battery up the wrong way round , then depending on which model you have, the controller may be destroyed in quite a spectacular manner! Only you can decide if this Read More

If you have read the page entitled Half-Bridge you will remember that the battery current is being switched on and off 20,000 times per second. Now electricity in wires has the equivalent of ‘mass’ – Read More

Most controllers are situated close to the user, e.g. in a ride-on golf buggy, so are controlled by a speed control pot wired directly to the controller. However some markets, such as Robots and some Read More

A tacho generator generates a feedback signal proportional to the speed of rotation, which can be used to provide closed loop control of a motors speed. Varying loads If such a ‘tacho’ is used and Read More