Originally Posted by Nectarines
@LurkingKnight, So 'mosfets' are addons that increase the life of the battery, motor, and the internal contacts on the trigger, by reducing the amount of power that goes to them, but still allowing them to operate at maximum performance. Therefore, increasing the life of your gun.
Not sure if this is correct or not, but it's about what I gathered from looking at pics and reading a post about mosfets on r/ELI5.
easiest way to describe what the function of a mosfet is that it's a relay. An aeg circuit is a simple loop, you connect it to fire it. Well some battery packs have a lot of power behind them, so at the point of connection you'll get an arc when the wires (in this case the contacts) get close. Eventually the arc will burn/carbonize the contacts. Sometimes it will burn them to smithereens and the gun will be unable to shoot... or worse, it fuses the 3 pieces of contacts together and it runs away, shooting until you can unplug the battery.
A mosfet interrupts this loop.... it adds a 2nd loop for the trigger that runs on minimal current/voltage... no arcing. Once this firing circuit is closed, the mosfet opens up the main circuit direct from battery to motor.
Most of the technical bits beyond that in terms of how it works are not terribly relevant at the beginner level. You can put a fuse in the main circuit if you so wish, or not.
In terms of efficiency, it does not extend the life of battery, it just creates a more efficient path for max power to reach the motor directly. You don't get more out of anything, you just make more use of what's already there.
It won't magically increase the life of any other parts aside from the trigger contacts. It increases the efficiency in which the electrical system operates.
Computerized mosfets have fancier functions beyond those... they have microprocessors and software that allow for burst firing, rate of fire control, motor braking, etc. One guy was even experimenting with using the computer to drive other peripherals like accelerometers and oled displays in a custom optic, theorizing he could if he had space, have a gps receiver outputting to the optic, hardware to run last round sensing, visual battery meter, etc.