by Steve » Sun Jan 03, 2016 4:16 am
It is an acronym. Stands for metal–oxide–semiconductor field-effect transistor IIRC. Fancy was of saying beefy transistor. The huge benefit of MOSFETs in microelectronics is that a tiny little current (like 40 milliamperes) can control 15 amps. This lets PLCs like arduinos control household 110v lights.
The units that get plugged into AEGs are and are not MOSFETs. They are really PLCs that HAVE MOSFETs incorporated into them along with other stuff, like Hall effect sensors and H-bridges and capacitors. Just soldering a straight MOSFET in an AEG is kind of retarded. All it would do is decrease performance very slightly and heat up a little (or a lot, and then blow up, depending on current).
There are a couple of basic styles of MOSFET units. There are some that plug in in-line with the battery and let you have burst fire and whatnot. These WILL NOT help with trigger contact arcing. All they really do is use a timer circuit to cut off flow of current to the motor after a certain amount of time has passed until they sense that you have released the trigger. There are (arguably better) units that get wired or soldered into the gun at various levels of complexity. The ones that WILL "protect" the trigger contacts from arcing damage isolate the trigger as a separate circuit. They run a much smaller voltage and current into the trigger loop and detect when the trigger is pulled. They then allow the bigger flow to occur through the motor. Since less flow goes through the trigger contacts, and no fly back from the motor gets dumped through the trigger circuit, you get less arcing.
If you are just looking to protect your trigger contacts, and don't care about the extra features, you could probably get better results for your dollars by soldering a diode across your motor terminals from + to -.
That being said: I think 3 of the 6 AEGs I run regularly have MOSFETs (PLCs, really). The rest of them will get MOSFETs installed when they need their next rebuilds. But, I play strictly indoors, running 11.1v LiPos, almost always on semi-auto only, and tend to dump 1500+ rounds in a 7 minute game. I'm pretty sure this counts as abuse in anyone's book. If you are less hard on your equipment, you probably don't need to worry about installing a MOSFET.