Mosfet w/ active braking suggestions?

[Tex]

Hey fellas, been a long time since I have purchased a mosfet and was just curious if you guys could refer me to a quality, reliable brand of mosfet with AB. It doesn't need any fancy bells and whistles, just needs to be a proven performer.

Many thanks in advance.

[T6e9a]

What sort of build is this going in? In my preference and research, AB MOSFETs aren't really needed if you tune the system appropriately. And they just cause more wear on you motor.

Just my 2 cents,

But GATE makes decent MOSFETs, and I'm sure they have some AB as well. I would look at them.

[Stinger]

T6 is right, an active-breaking MOSFET is not necessary and causes unneeded wear/heat at the motor. I would recommend the GATE NanoSSR. It is just a simple MOSFET, with no "bells and whistles." I like it a lot. I've used it in three builds now, one of which was my own. Also, one of my friend's trigger contacts stuck together and burned out his NanoSSR, but GATE replaced it for free.
If you truly do want AB, you can get the GATE NanoAAB, which is the same thing with active-breaking.

[ctres]

I would never recommend an active breaking fet, that doesn't sound very reliable. Now an active braking fet on the other hand, that is something worth considering in some circumstances though I would recommend you spare the motor heat and brush wear and simply correct overspin with a stronger spring and short stroking as needed.

[Stinger]

Oct 2, 2014 20:40:38 GMT -5 ctres said:

I would never recommend an active breaking fet, that doesn't sound very reliable. Now an active braking fet on the other hand, that is something worth considering in some circumstances...

Wait, what?

[ctres]

Break vs. Brake
www.gingersoftware.com/english-online/spelling-book/confusing-words/brake-break

I know you meant the latter, I was just making light of the misspelling. Anyway, the correct term is "active braking" since it slows down the motor. It does not break anything per se.

I'd recommend a standard 3034 fet from any of the guys on airsoftmechanics. You can get one with wires for around $20.

[Stinger]

Oh whoops haha
That makes sense.

[Tex]

Ahh we have a comedian here... to be honest I didnt realize it was braking.

Its for a G&P M4. I shoot almost exclusively in semi and in the past AB was the go to back in the day for that. I just dont want to have to open it up again to clean the trigger contacts. I have been having issues with over spin in full auto but will be upping the spring power to solve that. It shoots 335 right now and I'm going to push it up to 400 to try and sort that out.

Thanks for the advice, I knew some people here would be more informed about this than me .

[Tex]

Upped the M4 to an M120 spring and stripped the piston. Put a new polycarb one in and stripped that one at Bangor within my first mag. I just cleaned out, re-shimmed, re-greased and installed an SHS Piston w/ a metal rack and ground down the teeth for correct AOE. I installed the NanoSSR mosfet and am happy with the trigger response and rate of fire that I am getting with a 7.4V 1100mAh 20C lipo. Now to the problem:

In semi, the gears overspin quite a bit (30-50% of another rotation) causing the trigger to no longer be responsive after 1 or two shots. This is easily remedied by going into full auto which fires like a charm but the problem returns as soon as I go back into semi. The only thing I can think of is that the semi-auto cut off lever is getting stuck into a position where the trigger contacts cannot complete the circuit because of how the sector gear has spun. The only solution I can think of without changing my spring or gears, is to get an AB Mosfet. Any other solutions you guys can think of?

[Zzan]

The cutoff lever could be worn as well, which would prevent it from stopping the gear from spinning even if it is in the correct position.

The lever has a slight curve in the section that touches the gear. In mine when I had this issue the "point" closer to the fulcrum had worn down and prevented the lever from doing its job.

It didn't look worn, and I couldn't tell anything was wrong (having never replaced, looked at one before) until the new one arrived and I placed them side by side, then the wear was obvious. I put the new one in and the issue with overspin went away.

[Tex]

I inspected the cut-off lever when I had it apart and it was in good condition, showing almost no wear at all.

[T6e9a]

Do you currently have a MOSFET wire in? Of any sort? And what motor are you running with the setup?

You may have to combat the overspin with a stronger spring and short stroking. But id like to know more of the build before I have my final thoughts/suggestion.

[Tex]

Yes I have a Mosfet wired in properly with 1 wire attached to the trigger contacts. It is a G&P m120 high speed motor, it also has 8mm bearings. I do not know what ratio gears are in it but they are the stock ones for the G&P Magpul MOE CQB model.

I am not interested in a stronger spring as I would like to keep my full auto capabilities and the m120 spring I am currently using puts me close to the fps limit for that.

[snafu]

I know the having to switch to full auto is a bit of a recurring problem with g&p guns. I'm on my third one with the problem.

[Tex]

The problem wasn't always this bad. Then of course I fixed the shimming and the problem became much worse because there was less resistance for the spinning gears. It is pretty apparent that when in semi it over spins and the sector gear re-engages the cutoff lever causing the trigger contact trolley to pop up. Unfortunately this is where it stops and you have you pop it into full auto in order to get the cutoff lever to disengage and the trolley to complete the circuit again.

With this fet in and the reshimming and lubing the gun fires at a faster rate with the stronger spring than it did with the 330fps spring it had before. Never thought that properly shimming this beast would be detrimental to the performance but... behold, no more semi.