Yeah it’s definitely a hybrid Gen8/V2 mashup, similar to the JinMing Gen10 era 
Good news in the fact that any Gen8 aftermarket internal parts will fit, which are cheap, plentiful and in abundance 
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Hello peeps.
I stumbled upon this mosfet. Looks very easy and straightforward to install. Anyone familiar with it? all videos i’ve found about it are in russian.
I think @DocBob has had some successes with them.
I brought one in for a Gen 8 gearbox a few months back but it must have been a faulty unit. Went into full auto fire everytime a battery was plugged in. Local Einstein couldn’t get it working either so it wasn’t just my usual electronic dyslexia. 
Interested to see if it works for you.
Have used these with mixed success pn Gen 8. They are a pain to set up because of the interlinked function - like making sure you are set-up for 11.1v (which is hidden in the fine print). Burst mode is good but you can achieve the same with trigger control on full-auto. Tried to use it for semi on a Gen 8 box but fried the unit
Sounds like people have had varying results with these units 
I was using them years ago when there wasn’t much else available for Gen8’s and other early model blasters that required a MOSFET to take the loads off the trigger circuits.
Being programmable and having the ability to swap between blasters was a bonus too.
Never had any issues with these, but did notice that they disappeared from the market for a while and have only quite recently reapearred…so don’t know if they were having trouble with them or are being made by a different manufacturer now?
I believe that there’s more modern and better FCU’s available that would be a better option for reliability than these, but they are cheap and simple enough to give them a try out if you have the room to squeeze them into your particular blaster
I didn’t have any luck with the Urrkii MOSFET.
Not a lot of options with a Gen 8 trigger system being what it is… opticals won’t work with them. 
So what’s the dealio with the M4A1 Gen 8.5 that M4A1 were selling with fire select option? Is it running a MOSFET?
I have a stupid question
Since there is no mosfet in the gun, how does the trigger know to do only 1 cycle per trigger pull? I thought the trigger just closed the circuitry between the battery and the motor/mag which should just send it full auto.
nevermind, Chat gpt answered me lol
I might try the mosfet just for the heck of it. I see there’s an option to hardwire the trigger. I hope i can find a way to do it modular. Maybe soldering an sm plug to the contacts 
( I have those laying around since i converted my plugs to xt60)
I was wondering the same… a Gen 8 trigger is only a simple momentary switch.
What did you find out on Chat gpt? Because unless the 8.5 is running something like an Urrkii I can’t see how it single fires.
With that Urrkii, it does has to be wired to the trigger switchblock to work. It’s how modes are selected too, by trigger pull.
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I’ve wondered about the MOSFETs in Vectors, whether they could be wired into a Gen 8 build.
Be cool if they could… single, three round burst and full auto right there.
But with my electronic skillset or lack thereof, it’d be beyond my ability.
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there was a version of the gen8 that had a V2 trigger block setup instead of the momentary switch you know and love. Tac toys sold them for more than they were worth, and M4A1 originally sold the as the"scout" which although having metal gears and semi/full… was a bit on the plasticy feeling side even compared to a nylon gen8, and they were mostly nylon too just not as sturdy feeling as an actual nylon gen8. They now sell a gen8, and a gen8.5 that has the semi function.
Unfortunately the selector is also like the V2 counterparts, so not really interchangeable with original gen8 if you could find an 8.5 gearbox.
I know someone who tried to get the vector fet working in a gen8, even installed the little sector gear lever from a vector and a micro switch but seeing as glue was involved it never lasted more than a few games.
The same guy got one working in a p90 as they have a provision for a microswitch to be operated off the piston. It worked, but as the switch was right at the rear of the cycle it only worked correctly on 7v and 11v would overspin and double tap on semi, or offer a 4 round burst.
Delightfully though it was basically pre cocking every stroke, so it was pretty snappy on 7v semi auto!
So it can be done but the hours involved may not be worth it to you.
seems that there is a cutoff lever that’s activated by a cam on the sector gear (similar to the tappet plate, but on the otherside.) so when in semi, it physically break the contacts after 1 sector gear rotation. I didn’t notice this when i opened my gearbox but next time i’m going to look for it.
Side note: I have a toy gel blaster (in which i put the stock arp9 spring, surprisingly it’s still alive but that’s a story for another day) and it has a very interesting mechanism. when you put it into safe, a lever physically move the anti-return latch back, disengaging it and the gearbox naturally goes back to its resting position. I’m sure there are reasons why we don’t have this in higher end guns but i found it interesting nonetheless
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Be possible, just need the two extra switches to shoehorn in to whatever it is. Be a lot of work.
One switch to select and second shot count.
V2 is originally got the trip lever works off the sector gear with the selector plate on the side to set fire mode and all mechanical. Newer mosfets(or whatever you want to call them 
) have gone to like the hybrid has microswitches on the board instead of full optical. But I haven’t played with that. Does your trigger, sector, something else and cup of tea
To add to the comments already posted here, yes I had to add the two tiny trigger wires and a tiny 2 pin plug to each blaster to be able to swap the FCU between different model blasters, which still made them very convenient to be able to use across several different blasters instead of a permanently wired system in a single use setup
Not sure what other springs/motors/gears/batteries others have tried running these units with, but the bulk of my testing was done with relatively stock blasters on 7 and 11v.
As for information on the Gen8.5 series, I do believe that @AKgelblaster might be able to shed some more light on their setup… But definitely have the V2 style mechanical trigger interrupter for semi auto operation over the standard Gen8 trigger contact switch.
The best blaster technology for its era was the mighty SKD M4SS, with it’s revolutionary MOSFET FCU with safe/semi/burst and full auto fire select
As mentioned previously, this design also worked off a micro switch at the end of the cylinder for the piston to contact and allow the FCU to count single or 3 round burst fire.
It worked great… until the little switch arm got caught up on the main spring or fell apart during operation
My fix was to use different design micro switches with longer/more solid mount arms that I could bend into a better profile/position for more reliable operations.
The M4SS FCU’s/wiring/switches and connectors are still available aftermarket today, which means that they could still be a good option for a one off old school build with some more modern features
EDIT*
Just remembered, sadly the rotary fire select lever switch was also wired into the FCU and is NOT available aftermarket 
Think I’ll just feather the trigger.
I must be a bit on the spectrum because, seriously, I’ll tackle anything mechanical or
structural… fabrication of metal, plastic, fibreglass, you name it.
Throw a diode at me and my brain turns into a Simpson washing machine on the agitate cycle.
But that’s okay… like Dirty Harry said…
I’m lucky to have grown up with both mechanical and electrical skills, which is why I loved the Gelbaster hobby which combined these two interested and put them into a replica firearm for an added bonus of my other hobby!
I actually found it pretty sad when new products were released onto the market that took away much of the need for modifying/building/experimenting different components to see what results could be gained.
Plug and play just doesn’t provide the same satisfaction as coming up with ideas and doing things yourself
I agree 100%, Doc…
Maybe that’s why I enjoy owning the early blasters. nostalgic
Ditto, I’ll play with a certain level of it until it gives me the poops or what I’ve got time to fiddle around with and go back to welding and grinding. Sheep work. Looking at failed crops. It’s so much easier.
When I get time I can get some amazing things done, even amazed myself. But for me that’s the key. It’s just a hobby and only so much time I have for that. Each to their own and life.
same. Been into RC since 2001 (still have my first model). the shear joy of research, having a pile of boxes on the table and seeing it come together… I enjoy building as much as flying/driving my RC but today, like pretty much everything else, it’s mostly plug and play unless you get into high end expensive stuff…
Cool I like taking some time out and putting a Tamiya kit together when I get time. They have some really nicely built kit’s. Everything just fits. Cheaper ones also. I rebuilt my 1st from the 80’s recently as they re released the parts and as a kid I demolished it Needed some work but it was fun. Threw lipo and esc in it. Did aftermarket suspension on it to, because why not could never afford it in the 80’s, but now I can 
They are definitely not basher $2 grand type you can get these days in Traxxas but eh I can go drive a car in the paddock and do the same.
Run my 1/5th 5B too, had that must be 10 years now likely more, boy that is fun.