MOSFET suggestions
 

Dear all,

i'm looking to upgrade a few of my AEG's to using MOSFET, i have done some research but i was looking for advice from other GunDoc's as to what brand they use, or advise me to use...

the guns that i'll be upgrading are :
1. Top M249 W/PGC gearbox (hummer 1300 motor, with an m120 spring) will be run on a 7.4 lipoly
2. SPR mk12 Mod0 that will be upgraded to an M150 spring, guarder infinite torque motor etc that will be run on a 11.1v lipoly OR a 9.6v 3000Mah NiMH, if it can hack it.. ( i doubt, but i have three of these batt's and i'll make use of them if i can)
3. classic army M4, standard internals (shooting at around 380FPS) that i will run on either a 7.4 or 11.1 lipoly

so i'm looking for a total of three and it would be great if the one's i'll run in the M4's could support active breaking, but i'd preffer what works then any fancy features that may reduce the reliability.

i'm not too worried about the cost, but i want something that will work and has been shown to take a fair bit of abuse (my m249 will get plenty of it)

i'm very open to suggestions, but i would like suggestions toward places that have them in stock, as some locations i have seen written about haven't had stock for a while.

Where do you live?

I have been to Don's home to work on and guns and have him trouble shoot TM units he is a really stand up guy and I would recommend his stuff found here:

http://unconventional-airsoft.com/

He also sells via this board.

Gandolf from ASM makes excellent boards as well, they can be found here:

http://forums.airsoftmechanics.com/i...p?topic=2424.0

Triggermaster from DonP

Azathoth, i'm in cyprus (little island in the med' ) so everything will be ordered over the net.

i've seen the most about TM's.. but they're out of stock of the mk3 until later this month.. (guess i'll just wait)

anyone tried using the SMU? i was thinking of the MK3 for my SPR, and SMUs for everything else (but i'm mildly worried about how it would stand up to _long_ bursts on the 249, might grab another mk3 for that)

Thanks for the kind words and recommendations!

doc_pathfinders, the SMU is a good fit for the M249, they are in stock right now. Other stuff (as you saw) will be back in stock later this month (May 2010) when my new production run is complete. Feel free to ask any questions.

excellent, just the man to ask!

i'm sure that the TM Mk3 would cope with the load imposed by an M150, but as i have stated, i'm looking to put one of these in my m249, (m120 spring load, so not 'over the top') BUT i would like to know how well the SMU would cope with _extended_ bursts (upto/including 30 seconds) overheating is my main concern..

i guess i'm damn lucky to have you available to answer my questions :D

EDIT:
to be honest, i'm sold on the TM Mk3.. just need to wait for it to come in stock.

they are nice. for future lookers. if you want a bit cheaper the AB-Long from extreme fire is a pretty nice little piece. and has an inline fuse.

I have a TM myself but they get pricy. Although you can just move it from gun to gun and reset it each time :)

Trigger Master.

DonP is a great guy, he even made a custom MOSFET for me because I did not have enough space inside my rifle. On top of that, he quoted me a very reasonable price. Good comms and detailed instructions. What more can you ask for?

However if you want a really cheap pre-built-drop-in MOSFET, JG ones work as well. They have them for V2 gearboxes both Front and rear wired @ Airsoft Atlanta for about $40 shipped each.

Or you can the JG's from Huang, too. It's my gun, Skladfin is most likely referring to here... :D

I personally would avoid the JG units. I would rather goto the ASM and get a unit from Gandolf or AWS and one of there basic units.

Generally consensus on ASM is AVOID systema units

shoulda told me earlier =(

Damn, I thought you disliked mosfet's in general? I guess not... Anyway, Huang appears to be currently out of stock when I checked on his site a few hours ago.

Well, for what it's worth, dumping a JG in a gun doc's lap and saying "make it work good" isn't a horrible way to go - I, for one, know little-to-nothing about AEG's and thus trust *crosses fingers* that Skladfin knows his stuff and can figure out installation of parts and such. So far, he seems to have gotten my second AEG (also a second JG) up and running nicely... minus a few electrical problems related to motor connectors and the like (simple stuff that I just am totally clueless on).

can i just ask, what are the problems with systema mosfets?

I ask because i had come across them, and i had one in a PSG1 (shooting at 550FPS) i used to own.. and given the low-volume of fire it didn't do too badly.

The SMU should be able to handle what you throw at it with an M249 like that, just note though that with the Mk3 since the M249 has no semi-auto, it will be unable to use any firing modes that require the gun to be on semi-auto.

Visual aid:

+1 on triggermaster, but you should REALLY get your motors tuned, otherwise you'll just be overheating the motor and mosfet

DonP, thanks for the info, i was fully aware that i wouldn't have anything fancy RE: Firing modes on the '249 but IMHO a burst-firing SAW isn't something anyone should aspire to :P

also, i've been doing some reading on motor tuning, thanks for that bit of advice..

Be warned, I put one on my G&P, V2 mechbox, very stable platform, running an 11.1v 20C LiPo, and it's overheating on most motors after 200 rounds, 40 rounds on a systema magnum.
I highly recommend buying a G&P M120 or M140 and getting it tuned :)
I haven't had any issues since I tuned my G&P M120 motor

If your looking for a technical answer then any MOSFET with a Vmax over 20 an Imax over 30 should do for most AEGs Just make shure you heat sink it and don't forget that pretty much all MOSFETs take about 1.2V To turn on, so if you may need to upgrade your battery if your already pushing it.

you're not taking into account the peak current on startup, this may be many times the 'rated' current you believe the motor should draw when spooled up.. and as it's airsoft and we stop/start our motors (sometimes many times a minute) this becomes a big factor :)

i could pick up a DIY guide for making a MOSFET (and i have) but i'm looking for something that someone else's blood and sweat has gone into, rather then mine.. because i know that the first few versions will never quite work the way i want, or at all knowing how i punish some things..

also: ThunderCactus.. are you saying your MOSFET was overheating or the motor? and what were the symptoms?

The MOSFET itself wasn't overheating the motor per say.
The motor was not only drawing higher amperage than usual, but it also has a notorious overheating issue caused by lack of insulation. But the active braking makes it worse.
Due to the ridiculous amount of current being drawn by the motor in it's active braking and normal operating cycles, the MOSFET overheated

Ahhhh, it makes sense now :) thanks for that bit of info..

how did you tune your motor? true the commutator or using the 'water treatment'? (or did you hand it over to an RC shop and just let them do everything?

I have an RC guy with all the right tools, he's really good

bah! i'll have to check in with my local RC shop then to see if anyone will deal with AEG motors...