Explain mosfets to an idiot please

Hi gang, how are we doing?

I recently just upgraded the JM gen8 MP5 almost entirely short of a stronger spring, and the RoF is much higher than I was expecting with an 11 volt battery.

The motor is the red Chi Hai motor.

Bit of a feeding issue and battery heating up made me think that my eyebrows may be at risk/ need a sector delay chip.

I’ve heard of people using mosfets to regulate components of the blaster and I was wondering how essential a mosfet is, and if I’m right in assuming that the later releases have some kind of mosfet already installed?

Mostly interested in preventing a fireball at this stage, not wanting to draw the battery too quickly to risk an accident of some kind. But if there’s any sense in using one to control the RoF I’m all ears.

Thanks again

Hey hey…

Gets come in many types and with many functions but ultimately what they all share is this…

The are a big @r53 high current switch.

Whilst some have programming modes, fire selectors, active braking, precocking, low battery cutoff etm…the primary reason one would head into MOSFET territory is to remove the current load from the trigger assembly

More of a pre gen 9 thing where micro switching was used for the trigger contact.

So a fet isn’t likely the best answer for this problem?

Does it seem like I’m maybe a bit too cautious about the battery in this regard?

No…a get isn’t going to save the motor cooking issue.

It’s likely that the motor KVM / rpm is too high


The spring is too heavy and the motor not torquey enough.

Either way I’m not a fan of the chaihai motors and would replace it with an SHS which I consider more suitable entry level motor

You can get all sorts of nuts with these things but…m

I have some experience in this setup because I speced out a gen8 for a friend a couple of weeks ago.
He supplied all the parts of his choosing .
Chihai purple (against my advice)
18:1 shs gear set no delay chip
Shs 14t piston
POM Cylinder head and nozzle
Coloured S/S cylinder
Nylon tappet
10amp switch
Silver wire
1.3mm spring slightly shortened
7.3mm id S/S barrel
Rizer R1 hop up

Now I set it up on 2s Lipo since he did not give me a battery .
The rof is high but not mental and it ran very sweetly and fed perfectly and is doing 280fps, so he come over to pick it up and he tells me he wants to run 3s !
Again againt my advise he fires this thing up on 3s and its like a hose but still feeds perfectly and runs sweet.
So after setting his hop up it is as accurate as anything I have ever seen and the range is ridiculous even at only 280fps.
He used it all weekend mag after mag and it never missed a beat.
So anyway I would advise as a minimum to get a 10amp switch, heavy wiring and a good connector plus a battery that can handle it !
If you are having feed issues I suspect your tappet or nozzle is not moving freely, it took me quite a bit of work to get the tappet and nozzle dead smooth but it paid off :+1:


Thanks guys, a bit to work on.

I learned that it was the battery that was causing the wild rate of fire and heating up. I tried two 11v batteries, one being the wild one and the other a regular checker board one. The checker board one was way more reasonable, just a shame it’s too big to fit in the mp5 battery compartment.

If they are both 11.1v then the slower one is not doing the job and is being overloaded!
Use the other one :wink:

It’s still quite fast, faster than a 7.4. But not too fast that the gels won’t feed. Plus the magazines are tiny, get about two seconds of fire time before having to reload.

Those checker board lipos are poop !
Get yourself a high quality 7.4v Lipo and you will be pleased

Just at checkout now! Thanks for taking the time to list the build also, reassuring that I haven’t made too many bad decisions!