Jump to content
TheGrover

MOSFETs and gearbox cycling

This thread is over three months old. Please be sure that your post is appropriate as it will revive this otherwise old (and probably forgotten) thread.

Recommended Posts

Hey all, hopefully this isnt too much of a "Pain-in-the-arse" question.

 

I understand the basic workings of a MOSFET, basically bridging the trigger contacts, relegating them to carrying a signal current, rather than the torrent of power from a LiPo. What i wonder, is if a MOSFET system can be used to change the cycle of a gearbox, to create a much better trigger response.

 

Basically, the picture in my head of the perfect gearbox cycling system, is that on a trigger pull, the gearbox first releases the spring, then draws it back so that it is primed to fire at a a moments notice, so that the next shot is very snappy, and you don't need to go to unrealistic rates of fire to get a nice trigger response. A couple of safeties are required, firstly that the gearbox is forced to finish its cycle to prevent any half charged springs, and that a quickly accessible spring release is on hand (Ideally something similar to the Ares TAR-21, a button on the stock that releases the spring tension easily) so that when not firing for a period of time, you can reduce strain on the main spring.

 

I understand that some higher budget guns, like the Ares Tar-21 and either the ICS or G&G L85-A2 (or both, can't remember) have some or all of this functionality as standard, but could it be possible to make minor modifications, no more complex than fitting a MOSFET or shimming a gearbox, that will grant this functionality to a more traditional AEG?

 

Thanks for reading

 

TheGrover

Share this post


Link to post
Share on other sites

yes, you can buy them that do this, it is called pre-cocking. You can also get active breaking which means the motor should stop in the right place too. Programmable mosfets can also give burst fire, lock to semi, all sorts really.

 

The BTC Spectre is the one to get (if you can get hold of one.... rocking horse poo they are!) :D

Share this post


Link to post
Share on other sites

also, with a mosfet you'd be able to run an 11.1 LiPo which will sharpen the trigger up no end! :-)

Share this post


Link to post
Share on other sites

I think they exist but i don't like the idea of the spring being compressed all the time.... puts a lot of strain on the gearbox...

 

Tm's psg1 has that configuration

Share this post


Link to post
Share on other sites

I think they exist but i don't like the idea of the spring being compressed all the time.... puts a lot of strain on the gearbox...

 

Tm's psg1 has that configuration

I totally agree, which is why the Ares Tavor -21 (which features the pre-cocking system as standard) has a spring release which can easily be knocked to prevent that.

 

 

yes, you can buy them that do this, it is called pre-cocking. You can also get active breaking which means the motor should stop in the right place too. Programmable mosfets can also give burst fire, lock to semi, all sorts really.

 

The BTC Spectre is the one to get (if you can get hold of one.... rocking horse poo they are!) :D

Nice one. can a MOSFET also solve the spring release issue as highlighted above? such as holding the trigger on semi for a few seconds to release the spring tension? or will it take a bit of hardware work to install a manual spring release?

 

Thanks gents

Share this post


Link to post
Share on other sites

yup, you can set semi as normal cycle, then the full setting to semi with pre-cocking. I never use full auto btw so this would be how I'd set it up. or maybe semi with pre-cocking then 3 round burst without.

Share this post


Link to post
Share on other sites

yup, you can set semi as normal cycle, then the full setting to semi with pre-cocking. I never use full auto btw so this would be how I'd set it up. or maybe semi with pre-cocking then 3 round burst without.

great, thanks man.

 

i checked the BTC spectre, and it seems that its only available for a V2 gearbox, is there a similar model that fits a V3 without fiddling?

Share this post


Link to post
Share on other sites

great, thanks man.

 

i checked the BTC spectre, and it seems that its only available for a V2 gearbox, is there a similar model that fits a V3 without fiddling?

 

The King Kong Burst Wizard (www.aegwizard.com) can do pre-cocking and is a simple wire in type.

Share this post


Link to post
Share on other sites

ASCU - v2 or v3

 

http://www.airsoftsystems.com/?id=8

 

trouble is the whole classic trigger system is so dated and very prone to failing

the basic timing on semi relies on the cut off lever releasing the switch but in practice

it is more like yanking it out and trigger then engages it when you release trigger

 

absolute poxy design prone to wear & failure in a few places

 

still the main timing is the cut off lever & cam on sector gear for semi, or cycle

just as the main spring is released, the cut of lever pops/yanks the switch and stops the motor

 

So if you wanted the piston say 75% cocked then you could remove the cam on sector and perhaps

fit/bolt a new cam in a new earlier position - but this wouldn't have a release mechanism like on ICS's

for that you would probably need to rig up a lever to pop the anti-reversal latch to release the 75%

cocked spring - but another problem is tappet plate if it has loaded a bb - so there is a chance that a

double may be fed if released from 75%.

 

So having gun cocked @ 75% & release backwards may not be a wise thing or easily done without a fair

amount of work/cost to change the way the gun cycles as you put it

 

The super duper trigger systems are way way way overpriced and often out of stock now going through

many revisions, later versions now have mosfet(s) inside gearbox with the micro switches ans use the the

metal gearbox casing as a heatsink for the mosfets - clever but means you have to use their system not

others like Gate mosfets etc...

Plus you need to open up box to change/replace the main control system/mosfet

 

Also with many of these systems a bit of modification is required - some more than others, often the original

safety is removed, and perhaps anti reversal latch when used with high end motors....

 

I have been studying this dated trigger system lately and would prefer the older classic simpler design of just

low volt micro switches and leave the mosfet choice to me user(has to have a fet coz of low volt switches used)

Obviously the mosfet would be outside the box for easy change/replacement plus you do wonder how that box

and the shock when firing would fair shaking them components to bits over time

 

Your main objective of quick snappy trigger response might be better achieved by a higher torque motor, and

perhaps short stroking if still not enough trigger response for you.....

 

on average say guns fire anywhere between 15 to 25 rps - so say 20rps on a nice average setup for easy maths

that is a shot fired every 0.05 seconds and no real need for pre-cocked spring and all that....

 

Dunno how bad or desperate you need to be able to fire at a target quickly but feel a higher torque motor is perhaps

going to help you more with what you want - unless your trigger system is shagged and are looking at the new systems

but though they do these for both v2 and v3 gearbox's the price/availability is still way overpriced imho

 

so maybe you should get a SHS, GP, ZCI, Big Dragon high torque motor etc......

meantime I am still looking at trigger setup and toying with idea of throwing together own system instead of dated switch

Share this post


Link to post
Share on other sites

ASCU - v2 or v3

 

http://www.airsoftsystems.com/?id=8

 

trouble is the whole classic trigger system is so dated and very prone to failing

the basic timing on semi relies on the cut off lever releasing the switch but in practice

it is more like yanking it out and trigger then engages it when you release trigger

 

absolute poxy design prone to wear & failure in a few places

 

still the main timing is the cut off lever & cam on sector gear for semi, or cycle

just as the main spring is released, the cut of lever pops/yanks the switch and stops the motor

 

So if you wanted the piston say 75% cocked then you could remove the cam on sector and perhaps

fit/bolt a new cam in a new earlier position - but this wouldn't have a release mechanism like on ICS's

for that you would probably need to rig up a lever to pop the anti-reversal latch to release the 75%

cocked spring - but another problem is tappet plate if it has loaded a bb - so there is a chance that a

double may be fed if released from 75%.

 

So having gun cocked @ 75% & release backwards may not be a wise thing or easily done without a fair

amount of work/cost to change the way the gun cycles as you put it

 

The super duper trigger systems are way way way overpriced and often out of stock now going through

many revisions, later versions now have mosfet(s) inside gearbox with the micro switches ans use the the

metal gearbox casing as a heatsink for the mosfets - clever but means you have to use their system not

others like Gate mosfets etc...

Plus you need to open up box to change/replace the main control system/mosfet

 

Also with many of these systems a bit of modification is required - some more than others, often the original

safety is removed, and perhaps anti reversal latch when used with high end motors....

 

I have been studying this dated trigger system lately and would prefer the older classic simpler design of just

low volt micro switches and leave the mosfet choice to me user(has to have a fet coz of low volt switches used)

Obviously the mosfet would be outside the box for easy change/replacement plus you do wonder how that box

and the shock when firing would fair shaking them components to bits over time

 

Your main objective of quick snappy trigger response might be better achieved by a higher torque motor, and

perhaps short stroking if still not enough trigger response for you.....

 

on average say guns fire anywhere between 15 to 25 rps - so say 20rps on a nice average setup for easy maths

that is a shot fired every 0.05 seconds and no real need for pre-cocked spring and all that....

 

Dunno how bad or desperate you need to be able to fire at a target quickly but feel a higher torque motor is perhaps

going to help you more with what you want - unless your trigger system is shagged and are looking at the new systems

but though they do these for both v2 and v3 gearbox's the price/availability is still way overpriced imho

 

so maybe you should get a SHS, GP, ZCI, Big Dragon high torque motor etc......

meantime I am still looking at trigger setup and toying with idea of throwing together own system instead of dated switch

 

As for the spring release, i was thinking of setting the semi on the gun to a pre-cocked semi auto, then full auto to a standard full auto, so that when returning to the safe zone, just giving the gun a short burst of full auto with no mag (to clear the chamber) will ensure that the spring is not under tension, easier to do than fixing a manual spring release up.

and i do like the idea of using a micro switch in place of a mechanical trigger. does this also overcome the arcing issues and carbon build-up (leading to the death of a traditional trigger mechanism)?

Thanks

Share this post


Link to post
Share on other sites

Blimey - no need to quote all my crap I type - no wonder internet is slowing down

 

if you use microswitches then you MUST use a mosfet of some description and by that

I mean properly wired into the switch as the poor little tiny microswitches just can't handle

real juicy power switching from heavy high torque motors and big high amp batteries

they won't arc - they will just melt

 

the burst wizards are good but for full effect they should be wired into switch as on their own

they can be hit n miss if they work properly - otherwise they can be hit n miss for some setups

as peeps use different motor/batteries/springs so the loads will vary for each gun to another

 

The old school switch/trigger system is prone to failing in a few areas not just arcing/carbon build up

the way it is released - I'd say yanked by metal cut out/off lever and fact that metal lever yanking the

switch (plastic) means the switch is prone to wear, not just by the lever but also trigger too as it clicks

back into position - very clever mechanically but quite dated now and prone to wear

the pin behind switch which if fails allows the switch to return too far and trigger will not engage it again

this can happen and results in a dead trigger - zilch happens on auto or semi

 

Yeah i am looking into this coz fed up with a couple of boxes failing on trigger/switch and can't see why

still using dinosaur method - unless like many things it is a cost issue but no way should stuff like this be

£100 or even £50 ffs

 

you I feel would probably be looking at motor for improved trigger response is my gut feeling

 

I think the switch system should be just that and a mosfet in near battery - with an option to change/tweak

heck you can program the king kong/avacado burst wizards really easy or have a simple 3 pole switch to

say allow you to use on auto - full auto or 3 round or 7 round burst without config mosfet/wizard

say switch mounts on right or underside side of stock or ris and allows user to quickly change auto modes

depending on the developing situation around them - eg: low ammo/caught out in a 1v1 peeking battle

 

loads of possible different options and everybody will have different requirements and budgets

but present switch/cycle system is showing its age, but there have been numerous other ASCU's over years

most have been dropped/changed/updated so I doubt if it is that simple or easy to perfect a better system to

suit all users

all the same the present system needs improvement in my book

Share this post


Link to post
Share on other sites

The BTC Spectre is in the gearbox and uses microswitches I think they are trying to develop a V3 version. But getting hold of one is the hard part. Active braking allows removal of the anti reversal latch

Share this post


Link to post
Share on other sites

If you can't get hold of the BTC Spectre, the Gate Nano AB is an excellent substitute. They also make a Pico model:

asdf23432_zpsabc2eef9.jpg

 

While tiny and much more space efficient, my only worry with it would be accidentally crushing it while fiddling with battery connectors or losing it on a messy floor. That being said, this little thing is waterproof and gives good results, like the nano.

The nano is much easier to install though- it's literally got a male and female Deans connector on it (1 on each side) so you can just plug it in between your battery and trigger.

gate-elektronics-nano-ab-mosfet-active-b

(The black connector port is for a signal wire)

Share this post


Link to post
Share on other sites

The BTC Chimera does pre-cocking and does come in a V3 version, however it is oos everywhere. I emailed BTC a while back about this and after a while they emailed back to say they had some ready to sell, but by the time i had the money, a few days only, they were oos again. Afaik this sudden availability did not make it as far as Air Lab, their UK distributor. I can't actually remember how they deal with the issue of the spring being left compressed for ages, but they do deal with it - it is possible to get the cycle to end up simply completed.

 

I dont think the Burst Wizard KK does do pre-cocking and certainly the King Kong V1 barely works at all. It is also so complicated to program that it's kinda difficult to know whether you have ballsed it up yourself or whether it has failed. The new version II may well be better, but after how disappointing the V1 proved to be, i will not buy one unless I hear from someone on here who has had one working for a few months on a V3 GB.

Share this post


Link to post
Share on other sites

 

 

I dont think the Burst Wizard KK does do pre-cocking and certainly the King Kong V1 barely works at all. It is also so complicated to program that it's kinda difficult to know whether you have ballsed it up yourself or whether it has failed. The new version II may well be better, but after how disappointing the V1 proved to be, i will not buy one unless I hear from someone on here who has had one working for a few months on a V3 GB

 

I have a version 2 on my M249 in plug and play mode. WOrks fine for what I need. The instructions say it does precocking but only if it's wired in and I've not tried it as it's not a function I need on a support gun!

Share this post


Link to post
Share on other sites

I don't see the point of plug'n'play MOSFETS really, unless to convert to semi-auto only. But I will have to look into the BWKK V2 more carefully now, because pre-cocking is something I want.

 

However something else which the BTC Chimera does is ROF control by timing discrete shots, so you can have your GB cycling very fast, at 30rps say, but set the control unit to something realistic like 700rpm and in effect you get about 11 semi-auto shots in a second with tiny gaps between them - apparently it sounds very cool as well as saving ammo.

Share this post


Link to post
Share on other sites

what? no. AEGs don't have a bolt.

 

True, but it would make them fire from the piston being to the rear which is effectively "an open bolt" in real gun parlance.

Share this post


Link to post
Share on other sites

I don't see the point of plug'n'play MOSFETS really, unless to convert to semi-auto only. But I will have to look into the BWKK V2 more carefully now, because pre-cocking is something I want.

 

However something else which the BTC Chimera does is ROF control by timing discrete shots, so you can have your GB cycling very fast, at 30rps say, but set the control unit to something realistic like 700rpm and in effect you get about 11 semi-auto shots in a second with tiny gaps between them - apparently it sounds very cool as well as saving ammo.

 

Burst Wizard does that too: http://www.aegwizard.com/

 

(I'm not on commission by the way just offering alternatives)

 

My Burst Wizard is only plug and play bcause I only use it to give me a single shot burst on an M249 for a CQB site that requires semi in most areas. By leaving it plug and play I can easily whip it out and go back to full auto lunacy!

Share this post


Link to post
Share on other sites

No, that is one thing I remember quite clearly about BWKK's - the ROF is controlled by voltage, so it slows the cycle to lower it. With the BTC Chimera the cycle remains at the same speed, but the shots are timed electronically. I'm pretty sure that only BTC MOSFETs do this so far.

Share this post


Link to post
Share on other sites

No, that is one thing I remember quite clearly about BWKK's - the ROF is controlled by voltage, so it slows the cycle to lower it. With the BTC Chimera the cycle remains at the same speed, but the shots are timed electronically. I'm pretty sure that only BTC MOSFETs do this so far.

 

The newest version is PWM based.

Share this post


Link to post
Share on other sites

To me "PWM" stands for "Pulse Width Modulation" - I dunno what it means in this context...?

Share this post


Link to post
Share on other sites

To me "PWM" stands for "Pulse Width Modulation" - I dunno what it means in this context...?

 

I would assume that it means it's pulsing the drivetrain to control the rate of fire. Modifying the mark space ratio would allow you to change the RoF fairly easily.

Share this post


Link to post
Share on other sites
This thread is over three months old. Please be sure that your post is appropriate as it will revive this otherwise old (and probably forgotten) thread.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...