MosFet & Resettable fuse

JonnyTwoCombs

Does a MosFet need a fuse or will it operate without one?

Rooky1

Mosfets work perfectly well without a fuse!

I use mosfets in most of my aegs, and I remove the fuses as well.

Not using fuses is my personal choice, a lot of users will recommend you use them.

Firekitten

Rooky, question, why do you remove the fuse? what's the advantage as you see it? (curious)

Of course, no electical system NEEDS a fuse but again, As I said in the fuse topic just bellow, id rather use one and not need it, than need it, and not have it... that route is expensive, and hardly worth the expense, or as dex said, the rumour about gaining current and thus rof, is rubbish. As for resetable.... youve got me thinking now... mini rcd inline... there's an idea

Private Snafu

Firekitten wrote: »

Rooky, question, why do you remove the fuse? what's the advantage as you see it? (curious).....

There's more room to squeeze in a battery without, a prime example would be the VFC SCAR, putting the battery in it was a curse with the fuse, without it childsplay

Firekitten

fits fine with a fuse... the one here has one in :P takes a battery with no gripes. if you're upgrading to a 9.6, and need the space, Frankly, a fuse is EVEN more important at the higher voltage... if anything, its time to find a workaround and put one else where... or swap to a blade for size reasons.

Private Snafu

Try squeeze a 10.8V in , for some (like myself) battery space outweighs the risk of running without a fuse. As i've said 99% of airsofters know to let go of the trigger when something sounds wrong, saying that though I have repaired kit for people who destroyed wiring & connectors.

It all just comes down to personal preference really

Rooky1

As already mentioned 'battery space'.
Also squeezing in a mosfet is easier without the fuse housing.

I will be honest I have never had any problems with any of my AEG's not having a fuse.

Generally if an AEG stops firing or starts making odd noises I just take my finger of the trigger!:)

NakedDex

Whenever someone mentions this to me, I always give this example.

You say it'll work fine without, and you'll hear if something is wrong. Fair enough.
Take the fuses out if every plug in your house and replace them with a direct wire between the fuse contacts. After all, you'll probably hear, see or smell the toaster go on fire, or the dishwasher motor burning out, and sure you'll notice the tv suddenly going blank when you're watching it.

What I mean by saying this is that fuses are in devices for a reason. They're a preventative measure. Fixing the damage caused by an overload is closing the door after the horse has bolted. Fuses are designed to be the weakest point in the circuit. The next weakest is your wiring, and that's sort of vital.
Burned insulation can lead to short circuits. Short circuited batteries, if not disconnected immediately, start to rapidly heat up and can become subject to thermal runaway. This results in leakage at best, and often fire. I've seen cases where they've actually exploded.

It is personal choice, but I can't think of any good reason not to have one, especially since the parts it protects are located beside my face in the stock or behind a thin piece of plastic in my hand. Space may be tight, but fuses aren't exactly huge.

Rooky1

Wouldn't dream of removing fuses from mains appliances, that would be stupid.

Some AEG's already come with no fuses in them and work perfectly well like that.
As has already been said each to there own. Personal choice, etc.

NakedDex

Well you average household appliance uses only a portion of the current used by an AEG, and the surge current of an average rifle is orders of magnitude higher than anything in your house.
It's just as dangerous either way, but at least the appliance has the MCB/RCD/RCBO/fuse to fall back on. Your rifle just enters self destruct mode.

As for some manufacturers not shipping with fuses, don't confuse that with a manufacturer acknowledgement that they're not needed. They do that simply because a fuse carrier, plus a fuse, is about 20c in trade price. 20c saving over several thousand units is quite a wad. Not to mention it removes an entire process in the manufacturing line, saving time, process equipment and wage costs.
They're not omitting them because their systems are immune to fault, they're doing do because it saves them money.

Rooky1

Again it is all personal choice.

I have been using AEG's for well over 7 years now and have never had an AEG fail, because it didn't have a fuse.

I understand your points, but don't personally see it as a problem.:)

NakedDex

Nor am I saying you should immediately run out and fuse everything. I've been using AEGs about as long as yourself, but I've been heavily immersed in electrical and electronic systems for twice as long, so I've seen the undeniable benefits of having them, and the catastrophic failures caused by not.

Also, nothing fails because it didn't have a fuse. Items fail because of faults. Fuses simply prevent those faults from propogating beyond the weakest point of the circuit and causing anything from minor damage to complete destruction.

Rooky1

Coolio I take your points onboard.:)

I think we have strayed a little from the OP's original question:rolleyes:, for which I apologise.

THE MINDER

Thread brings to mind a little experiece I had with an active break mosfet(Wont mention maker)no fuse fitted, into a G+P stubby type stock(loads of room)it did work fine until halfway through the game the marshall informed me I had smoke coming from the stock-QUITE LITERALLY A SMOKING GUN:eek::eek::eek::D:DLOL -the whole lot had melted ending in the battery shorting out.Although I mostly remove fuses from my aegs to reduce resistance(long debated question in airsoft forums) When using mosfets I will now use an ACTIVE BRAKE MOSFET WITH BUILT IN THERMAL FUSE which I feel does not cause the same resistance as a standard fuse an does'nt take up extra space-covers both angles(me thinks)
Dave.:)

Firekitten

standard fuses do not have resistence enough to slow down your gun :P Debated or not, it doesnt. :P (oh man this is going to go off topic)

JonnyTwoCombs

Firekitten wrote: »

. As for resetable.... youve got me thinking now... mini rcd inline... there's an idea

This is the one I got. Cost about $10 plus P&P

I'll PM you the link to the site if you like.

NakedDex

Firekitten wrote: »

standard fuses do not have resistence enough to slow down your gun :P Debated or not, it doesnt. :P (oh man this is going to go off topic)

Ding ding ding! We have a winner.
Take a multimeter to a fuse and check it's resistance. If it's a particularly small one, or it's a bad one, you might get a couple of milliohms (assuming your meter actually even reads that low, many consumer ones don't). Generally, they're in micro-ohms. This resistance is so low that you'll actually need a specific type of meter just to test it.
It's going to cause absolutely no effect whatsoever on your rate of fire. None. Nada. Zip. Zero. Ever.

Gatling

which is the better fuse standard glass or the blade automotive type ? my ics 551 use's the blade type

NakedDex

Neither is "better" exactly. They're just different shapes.The main difference comes in what they're actually designed for.

Glass fuses are rated for a maximum voltage of 230Vac, so they're common in a lot of devices. They're sort of a general purpose mini-fuse, hence the wide variety of current ratings they're available in, as well as two different time variants and two sizes. In most cases, glass fuses are also cheaper than blade types.

Blade fuses are automotive grade. They're designed for use in circuits that never go beyond 42Vdc. There's a negligible performance benefit from that fact in airsoft devices, but the blade fuse is easier to change and has a smaller overall size, so it's popular with manufacturers where space is tight. They're also easily found in motor stores, unlike glass fuses which are usually only stocked by electronics suppliers.