The Mosfet Thread

[Clot]

I burnt out two fets trying to get it working on an ICS gearbox. I gave up, and did some reading to find that it couldnt be done. Not sure why, how, or if a work around is possible. I just gave up to save myself from wasting more money.

[Clot]

To Add.. If I am wrong, please tell me!! I really want to know how it can be done.

[tiff_lee]

To add if I cycle with the top off the sector gear comes all the way round just past the point of engagement with the piston although with a wiggle and what not I can get the top on still. As I said with the top on it stops dead at cutoff point pretty much, I have tried a little filing/bending on the trigger mech and cutoff lever to see if I can get around this but I actually broke the tappet plate taking the top on and off so put it on hold for the moment.

[GrenadierMasada]

To Add.. If I am wrong, please tell me!! I really want to know how it can be done.

 

my local airsoft shop has done many an ICS in their gb. You have to snip off some of the contact points that touch the selector plate so it wont ground on the body. hope that gives some insight.

 

now ive got a question. i installed a JG mosfet and now the thing wont shoot full auto. only in semi. bums me out, as the battery fitting in the stock is even more of a tight fit, and ive already had some issues setting the motor properly. grrr. now the damn thing wont shoot full. please let me know of something to do. . thanks

[Rincewind]

Having just read this thread, and having just bought a ICS m16a3, would like to fit a 3 round burst mosfet

 

 

the couple of posts above have concerned me, is it possible to fit into a ICS? or is there other mods that require doing??

 

 

having never opened up the gearbox on one, with the exception of the top part, i'd appreciate to know just what i could be letting myself in to....

[zerograffit]

Sorry to but in...

Is my fet good to handle airsoft on a 11.2v lipo? Irf3205

 

vdss 55v

rds 8.0 ohm

id 110a

pd 200w

 

Full auto seems good but in semi

2-4 semi shots, it gets really hot

 

http://www.irf.com/product-info/datasheets/data/irf3205.pdf

[DarkLite]

G&P M120 motors are starting to really ###### me off - they drain so much current that they fry my mosfets after a few cycles.

 

Anyone else having issues with M120s and mosfets? It's literally ONLY the M120s that have issues - all of the other setups I've run have no problems at all.

[sniperiain]

ive noticed that my mosfet with AB overheats like crazy if i use a battery with higher voltage and MAH, for example, i cant really use my G&P 9.6 3300MAH battery anymore because the mosfet gets far to hot! i have to use little 7.4 20c 1200mah li-pos but i dont get teh same fantastic ROF or trigger responce, if i use a 11.1 li-po that is a different kettle of fish all together, a 25c 11.1v 2200MAH li-po almost fryed the mosfet after 10 single shot in succesion.

this should be normal? my m16 is a CA m16 with a guarde FTK and G&P m120 motor, it should be overheating! even my "stock" galaxy mp5 can handle 11.1 li-pos and has done for nearly 6 months, never had to open the box on it. could it be a problem with the mosfet or is it an internal problem?

cheers

iain.

[Clot]

Darklite. What mosfets are you using ? For a while I exclusively used m120 motors and have never had any problems. I built several high speed ak's with them, and had zero problems.

[SteevoLS]

I use 3905 and 1404z MOSFETs in my braking units. I've sold about 50 with that combo so far; my first and only failure was after one game on a G&P M120 motor. On the flip side, I can spam semi-auto shots all day with my VFC motor and have no problems, and hardly any heatup.

[Eugene_Stoner]

I have infected fets in all my G&Ps and run M120s in all 4, no probs here, perhaps a short somewhere?

[DarkLite]

I'm running IRF2804s, rated to 280A and 40V maximum. I've just managed to fix one of the M4s - it was a short caused by a gunked trigger unit. Well done, G&P, white lithium grease in your gearboxes, not going to be an issue at all with all those plastic and rubber parts...

 

On the other hand, the other M4 with an M120 motor has eaten three seperate mosfets so far, even though I've opened her up so many times and checked it's all ok. Gah.

 

On the other hand, one of my oldest Mosfets is running in my AKSU - for nearly 2 years now with regular usage - She's running 360fps on 7.4v lipos with a Monster ELEMENT Ultra Torque motor in her, which is ludicrously responsive, but a bit of a battery hog. Even though I once fell into a sinkhole whilst fording a river and had the mosfet short out - I went completely under with the gun for a good 10-15 seconds before I got above the surface again - I dried it out under a radiator and it's still going strong.

 

I've also built a semi-locked Sg550 DMR firing 450fps with one of my fets, no issues at all.

 

So it's not the fet's I'm using.

[infected]

@Darklite

 

What spring strength are you using with that? Could be heat build up with higher fps springs and using the gun in semi auto a lot. I find the Matrix Turbo to be a better choice these days as it has a bit more torque while still having a ton of ROF. The only problem is trying to fit them in to things like TM M14 motor cages.

[mamba17]

I have installed a dozen of his world famous mosfet when I got back to UK after spending a well deserved vacation in US last March.

 

My normal set up for all my clients 350FPS, using 7.4V lipoly 1200mah 15C, good to go 20 ROF, for reliability.

 

Mine though are running at 28-30 ROF.

 

No problem yet with this mosfets.

 

 

I have been using extreme fire mosfet ( first gen Panther) which Sir Gandolf sent me several years back, I have delegated this mosfets for milsim due to its 3 round burst capablities and the other one (cheetah) was set om my M4 based DMR.

[DarkLite]

@Darklite

 

What spring strength are you using with that? Could be heat build up with higher fps springs and using the gun in semi auto a lot. I find the Matrix Turbo to be a better choice these days as it has a bit more torque while still having a ton of ROF. The only problem is trying to fit them in to things like TM M14 motor cages.

 

One setup was 350fps, the other 370fps. The M120s just can't seem to handle anything above 330-350fps without draining stupid amounts of current.

[Schultz98]

 

 

On the other hand, one of my oldest Mosfets is running in my AKSU - for nearly 2 years now with regular usage - She's running 360fps on 7.4v lipos with a Monster ELEMENT Ultra Torque motor in her, which is ludicrously responsive, but a bit of a battery hog. Even though I once fell into a sinkhole whilst fording a river and had the mosfet short out - I went completely under with the gun for a good 10-15 seconds before I got above the surface again - I dried it out under a radiator and it's still going strong.

 

Now thats impressive! I just got my first mosfet in one of my guns, I put an infected AB mosfet into my RPK and Im getting a really good rof(over 20) with my gun with a 7.4 15c lipo, 350fps, and a stock classic army motor.

[infected]

An m120 motor should do fine with a 400 fps spring.  That said, the matrix turbo or 5ku motors will do better.<br>

[Kipper]

Well after ages of fiddling by the tech it turns out the motor was shorting out on the base plate. What are the chances?

[dt00th]

i run homemade mosfets systems in all my Aegs 320 to 360fps on 7.4v 2200mah lipos one has a systema motor never had a problem with them will get the mosfet code if i can find it

[dt00th]

i believe its this one MOSFET N-CH 60V 100A 3-Pin TO-3P RS Stock No. 671-4979

[backfire]

Hi, i've decided to build my own AB Mosfet circuit for a TM G36c upgraded to about 350fps and using a 7.4v 2200mah 20C Li-Po Battery.

 

These are the Mosfets i picked:

 

N-Channel IRF2804

 

P-Channel SPP80P06P

 

 

I have read that the internal resistance of the P-channel mosfet must be relatively high, otherwise bad things will happen. I've seen the 80P06P pop up a few times on this thread. I assume it is suitable for the purpose?

 

What is the heat build up like during operation? Is there a way to insert some kind of heatsink into the circuit as an extra precaution?

 

Is the glass fuse that came in my aeg ok to use, or do i need to make another one for the mosfet?

 

Are there differing grades of solder to use or is the cheapest one as good as any?

 

Also i see that the resistors have varying values of wattage (1/2W, 1/4W), is there a better value to use?

 

 

 

I'm not electrically minded hence the questions, so any help appreciated!

 

 

P.S. Here is a video demonstrating the difference between a non-AB and an AB mosfet.

 

LINK

 

***EDIT: Forgot to add link***

[Mat]

Hi all,

 

I had a mosfet fitted by someone a while ago, but there is a fault that means when there is a battery connected the trigger does not release in semi auto. The trigger can be moved forward manualy and will fire again, but it stays back when fired. When there is no power the trigger moves as normal.

 

Suggestions, I'm hoping this can be a home fix as getting it sorted by the gunsmith isn't really an option atm.

 

Thanks in advance for your help.

[infected]

Hi all,

 

I had a mosfet fitted by someone a while ago, but there is a fault that means when there is a battery connected the trigger does not release in semi auto. The trigger can be moved forward manualy and will fire again, but it stays back when fired. When there is no power the trigger moves as normal.

 

Suggestions, I'm hoping this can be a home fix as getting it sorted by the gunsmith isn't really an option atm.

 

Thanks in advance for your help.

 

Sounds like you have a mechanical problem, not an electrical problem. I would start a separate thread for this and make sure to mention the actual type of gun in question.

[backfire]

Just wanted to know if anyone could give me some info on the resistors. Do they have to have certain Amp and Volt or power ratings or are any ok to use as long as they are of correct resistance?

 

 

 

backfire.

[Mat]

Sounds like you have a mechanical problem, not an electrical problem. I would start a separate thread for this and make sure to mention the actual type of gun in question.

 

If the trigger works fine when there is no power but only locks back when there is a current running through it, I'm pretty sure it's an electrical problem... else surely it would do it whether there was power or not?

 

It's also worth mentioning (which I forgot to add, it doesn't do this in Full Auto, I'm convinced it's electrical, a mechanical fault would surely exhibit itself whether powered or not. On advice from elsewhere I'm going to have a check for any bare wires... a long time since I did anything electrical so I may have missed the obvious the first time.