What are fets
 

Hey. As you can see from the title what are fets. I have like 3 long strips of them so like 30 or so and i know this size fet is for an xmod. But what does soddering them on do and allow the car to do. And is there such a thing as too many fets on 1 car

And is there a way to explain that in layman's term because i dont comprehend it

I was curious so I looked for someone who uses them.. found some basic info that seems easier to understand.

google 'Xmods Fet'

"The FET in a mini-z or xmods car takes power from the batteries to the motor. The FETs on the board can only take so much current before they over heat or fry altogether. This can happen when you are using a high current or "HOT" wound motor. Some people either replace the standard FETs or stack more fets on to to spread the load. Stacked FETs can start to get very hot and if you stack to many the eventually end difficult to fit in the car. The other problem is all that current has to come through the standard board which can create a bit of a bottleneck. This is why I decided to try building my own external FET board."

A FET or MOSFET is a semiconductor. It has 3 pins. Think of them as an input, an output and a control pin (actual names are source, drain and gate respectively). It's basic job is to regulate current and voltage from the input to the output via information it receives through the control (gate). In an ESC, this is the component responsible for regulating the large amount of current that travels from your battery to your motor.

If you can't understand the Wikipedia page, then you lack the fundamental ability to use those FET's effectively. Not to say you can't learn those things (many people have), but you have a long way to go from that little knowledge, to the point where you could successfully replace the FET's.

If you could find someone with circuit board soldering experience, they might be able to help you.

Do you know how a mechanical relay works. Where you have a lower voltage/current that you switch on and that sends power through a wound coil creating a magnetic field. That field than sucks in contractors that switch your higher voltage/current circuit.

Transistors and fets basically do the same switching but use the properties of doped silicon to do the switching.

The point is that with many types of control circuits you need to be able to turn off/on larger voltages/currents then a processor can handle so the processor controls the fet to handle the heavy lifting.

Not familiar with the mini z but it looks like they are added fets to add a larger ability to switch higher currents.

really?? he is a rookie... how about helping him out or dont comment.. this is your warning.... thank you

if you want to learn.. start with a simple transistor.. it does NOT handle large power.. but will teach you many things.. an will lead you to FET's.

Radio Shack used to make project boards.... so learning and making electric stuff.. simple stuff..

soldering and doing FET's. is not something for beginners.. as soldering can COOK them..

I was building FET projects in the early 1990's... RC battery discharges.. 20 to 40 amp.. controlled, regulated. and inputted into Apple computer for plotting.

if you are NOT careful .. you can KILL your controller..

I know Electronics.. I can NOT teach it...

Long story short, they're a big electronically controlled switch. So now you're asking, why do I need that?

Your electronic speed controller is a microprocessor of sorts, and is a fairly dainty little thing. Capable of handling "a few ma" of power on any particular pin, at rather low (most likely 3.3v) voltages. Realisticly, the daintyier the better, as it will suck up less power you intend to use anywhere else.

Your Xmods will draw 4-5-12 amps of power, when you hammer the throttle. That processor that takes your radio singals and tries to control your motor, can only handle those few ma. But what you can do, is use that little bit of power, to control a LOT of power.

Transistors are the second tool we had to do that. They can take really small signals, and amplify how much work they can do. (first being tubes, but lets pretend those horrors aren't a thing.) Transistors require a fair amount of current to keep switched on. And the more power they pass, the more current they need.

That's a problem, since our dainty little ESC processor can only generate so much current, and that current needs to be at a proper voltage so the Transistor doesn't do something really sily. Like operate in a "analog" range. You can read "analog" as "heater". They don't like living there. (There's special transistors to help this, called darlington pairs...)

FETs are the solution to that. They are voltage controlled switches. Go above the right voltage, and they switch on, and switch on hard. And skip most of that analog region.

Transistors and FETs both have some resistance, and at the voltages you run, a few miliohms of resistance, is a BIG thing. By stacking FETs, you're dividing the resistance that the switching part of the circuit has. Two FETs have half the resistance... It also helps with the current carrying capacity.

FETs have current capacities, which if exceeded cause them to let the magic smoke out. That's where stacking them helps two. Having two FETs doubles the current carrying capacity of that part of the circuit.

The ones the OP has, are actually 8 pins...

I was just speaking matter of factly. He has a very rudimentary understanding of electronics, and I am in no way trying to insult him for that. He is curious enough to ask (in a very appropriate place, and with posts that are readable), and honestly that is great.

But for him to go from very little knowledge of electronics, to soldering on a pcb is a lot to handle. Just the equipment alone is $$$$. There is a stickied thread here with 220k+ views dedicated to soldering, and I doubt there is much info there about pcb soldering because it is hard to do, and not really common for most people involved with rc.

Like I said though, many other people have had to learn that stuff, and there is no reason he can't learn.

If he really wants the FET's added to his car soon, his best bet is to find someone with pcb experience, and see if they will do it for him. It's only 8 solder joints so they probably wouldn't mind helping. Plus seeing pcb soldering live will be a good learning experience.

Again, just trying to be helpful. Not trying to insult him.

It is a kind of transistor. Normal transistors are controled by a current and a FET (as the word says Field Effect Transistor) is controled by a voltage. The have a better high/low impedance than a normal transistor and so in our RC cars a better choice for less loss of power.

But they do have an impedance, that is why they are stacked in a mini-Z. The parallel stacking does (like with resistors) lower the impedance leaving more powe to the motor.

But my questuin will be, if you have no clue what it is and you have that many of them, how and why did you get them.

something like this

https://www.amazon.com/RadioShack-28...tronc+projects

Some one sold me there xmod lot i mainly got it caise i saw 2 awd kits skattered in there and when i got the package it had 2 tubes labed gen 1 and they had fets in them and some boards which im guessing are external fet boards. Which was going to be my next question to you guys ill post a pic, and he also had a bag with 2 long strips of fets but im not sure if they are the same they are the same size and all.
https://cimg9.ibsrv.net/gimg/www.rct...f2c647e661.jpg