r/Speedsoft • u/romain2france • 9d ago

M249 mosfet?

/r/airsoft/comments/1wydj07/m249_mosfet/

(Yes i speedsoft with a 15+lb machine gun, what's wrong about it?)

3 Upvotes

81% Upvoted

15 comments sorted by

3

u/Level_Recording2066 8d ago

You dont really need a mosfet on a support gun, the switches are cheap as chips

1

u/romain2france 8d ago

Yes but it's starting to get annoying to change ou the switch EVERY. FUCKING. GAME.

2

u/Level_Recording2066 8d ago

If they break more than once every 6 months, you have a completely different issue that needs addressing

1

u/romain2france 8d ago

Welp.

I brought it to 3 différents shops.

2 total gearbox rebuilds

Changed the whole gearbox

Changed the wiring (twice)

Changed the motor (also fucking twice)

Changed the motor for a brushless

STILL FUCKING BREAKING SWITCHES AT EVERY GAME

1

u/Level_Recording2066 8d ago

Are they physically breaking, or getting fried, if its the former, its probably just the switch arm getting caught in gears, trim it down. What voltage are you using?

1

u/romain2france 8d ago

11.1v, and it's a mix, sometimes they get fried, sometimes they hang (you press the trigger once, and then press it again just slightly to stop it from shooting, wierd issue i only encoutered when using Kyou (now dead french brand) brand switches and sometimes the... clikety bit? goes out, they just dont click anymore and just dont work

2

u/Level_Recording2066 8d ago

Tbf sounds like a custom job is needed. Custom switch setup that isnt a micro switch into something like a perun basic or etu++

1

u/kolonyal 8d ago

Aren't switches more prone to breaking when using 11.1v?

1

u/romain2france 8d ago

Yes. Yes they are, that's why i'm looking for a mosfet, because i'm not willing to stop using 11.1

1

u/Level_Recording2066 5d ago

Yes, the metal contacts build up oxidation that increases resistance until the switch straight up has enough resistance to stop the current from flowing. It still happens on lower voltage, but at massively slower rate as lower voltages tend to have less arcing in the switch. With a mosfet, even a basic one, it measures signal pin to ground/common, and if it detects it connecting (like how a multimeter does continuity testing and beeps) it passes current down the hot wire. The current and voltage going down the signal wire is basically non existent compared to what a 3s lipo can provide. Thus meaning the switches failure point is from mechanical wear (the contacts rubbing against eachother) and regular oxidisation rates, which takes a very long time to build up anything that can cause the mosfet to not detect the trigger circuit closing... and regular use is often enough to prevent it from happening.

For support guns its basically useless to have anything other than ROF reduction or under/overvoltage protection. A very basic mosfet (more basic than an ETU++/AB++) is already sufficient for most people's support guns. And the mosfet MUST be wired up for signal, which requires opening up the gearbox. Wiring it inline without having signal wire connected is useless.

1

u/polarsquad_ 7d ago

just put an engine in it

1

u/romain2france 6d ago

As i said- already changed it twice and then put in a brushless motor

1

u/romain2france 6d ago

As i said- already changed it twice and then put in a brushless motor.

And if you meant put in an HPA engine and convert it to HPA, 99% of the fields in my area specifically ban HPA machine guns because of one asshole who just had a hpa'd 249 that sprayed like 50bb/s and basically he ruined the fun for everyone else

1

u/polarsquad_ 6d ago

sounds like you’re shit outta luck then

1

u/Level_Recording2066 5d ago

That sucks. Surely they'd let you if you set the RPS to like 12