|Aug 07, 2012, 12:11 PM|
United States, PA
Joined Dec 2011
MOSFET - The thing that drives our motors
Yes, MOSFET - Metal Oxide Semiconductor Field Effect Transistor.
In the beginner section, one should not abbreviate. Spelling out what MOSFET stands for only makes it worse.
In the case of the DH9116, they are power transistors that are controlled by an electrical charge on the "gate". Put zero volts (ground) on the gate and the transistor turns off (turns very off, like it isn't there). Put +5 volts on the gate and the transistor turns on (turns very on, like a direct short). The gate only needs a voltage and no current, so the power needed to control the MOSFET is practically zero watts.
Fantastic devices. The two MOSFETs on the DH9116 printed circuit board can switch (I seem to recall) 80 amperes to turn the main and tail motors on and off.
A short circuit dissipates no power. An open circuit dissipates no power. The MOSFETs only dissipate power during switching, the transition between a short and an open.
But voltage spikes from the motor's inductance during switching will kill a MOSFET. So, across the main and tail motor connectors are "snub" diodes to short motor spikes.
Enough electronics. MOSFETs are such a mystery to RC helicopter pilots, but are as vital as the LiPo batteries.
|Category||Thread||Thread Starter||Forum||Replies||Last Post|
|Discussion||AR.Drone 2.0 Motor Controller MOSFET Fix||rmllenado||Multirotor Talk||6||Apr 28, 2014 03:43 PM|
|Discussion||Simple things that bring joy...||RCWorks||Life, The Universe, and Politics||36||Jul 09, 2012 11:52 AM|
|Discussion||The dumb things we did... That we shouldn't have.||RCWorks||Life, The Universe, and Politics||23||Jul 06, 2012 07:33 AM|
|Discussion||10 Things You Get Now That Obamacare Survived||dll932||Life, The Universe, and Politics||38||Jul 05, 2012 02:28 PM|
|Cool||I think our motors are slowing things down||Flyextreme||High Performance||1||Mar 09, 2012 07:13 PM|