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Author Topic: Question about fuses/FETs  (Read 983 times)

Offline deathbydanish

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Question about fuses/FETs
« on: April 10, 2006, 02:00:43 AM »
With regards to AEGs, all I know at this point is that a FET can be used in place of a fuse. The actual benefits and installation of an aftermarket FET is quite literally beyond my knowledge.

Here's a pic of one Angel makes



Hope that helps.
« Last Edit: December 31, 1969, 05:00:00 PM by deathbydanish »
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Offline LiquidSky

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« Reply #1 on: April 10, 2006, 09:19:27 AM »
it's like an electrolytic converter helping regulate a constant volt through your circuit. yes? no? maybe?

ok....let's say you have a battery that actually pushes a constant 10 volts. with the constant opening and closing of the circuit (READ: firing the airsoft weapon), your voltage through the circuit will actually fluctuate (+/- 3 volts). the FET/Electrolytic converter will absorb a certain amount of charge and help the circuit constantly push the 10 volts available.

the numbers aer theoretical in this situation but that's the lamens definition of how it works.

never once have i used one. or a fuse for that matter. not in airsoft weapons.
« Last Edit: December 31, 1969, 05:00:00 PM by LiquidSky »
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Offline Phreakish

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« Reply #2 on: April 10, 2006, 10:49:23 AM »
interesting... never heard of that, but a FET (from my understanding) is usually used like an on/off switch...

with that 'extra' red wire, it looks TO ME, like that assembly is supposed to work like this: the fet replaces the trigger switch, since the trigger switch can only pass so much current, before heating up and burning, you run a FET (or relay) that opens/closes with the trigger switch, and then the current to the motor is actually passed thru the fet/relay to get max power to the motor.  Basically, the fet/relay can pass MORE current than just the trigger switch can, especially w/o burning up the contacts in the trigger...

At least, thats what it looks like to me, I'm going to be building/doing something similar with my m14 soon, as the trigger contacts are wearing out and I dont want to have to open the gearbox to replace them again...
« Last Edit: December 31, 1969, 05:00:00 PM by Phreakish »
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Offline LiquidSky

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« Reply #3 on: April 10, 2006, 12:38:35 PM »
"...the current to the motor is actually passed thru the fet/relay to get max power...Basically, the fet/relay can pass MORE current than just the trigger switch can"

this is the process of an electrolytic converter.
« Last Edit: December 31, 1969, 05:00:00 PM by LiquidSky »
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Offline Phreakish

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« Reply #4 on: April 10, 2006, 01:17:29 PM »
Yeah, I understand that, I'm merely trying to point how exactly how it works, it just about replaces the trigger switch with one that can handle more power, and trigger that fet/relay with the original trigger switch...
« Last Edit: December 31, 1969, 05:00:00 PM by Phreakish »
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Offline seanm028

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« Reply #5 on: April 10, 2006, 04:56:08 PM »
So would you guys reccomend them?  How common is it to actually wear out trigger contacts?
« Last Edit: December 31, 1969, 05:00:00 PM by seanm028 »
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Offline andyhinds

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« Reply #6 on: April 10, 2006, 04:59:03 PM »
If you tie the Gate to the Source of a FET (Field Effect Transistor) the max. current passed through it is the IDSS rating of the FET.  Basically the FET acts as a constant current source.
« Last Edit: December 31, 1969, 05:00:00 PM by andyhinds »
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Offline Phreakish

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« Reply #7 on: April 10, 2006, 09:50:30 PM »
Quote from: "seanm028"
So would you guys reccomend them?  How common is it to actually wear out trigger contacts?


I'm going to be installing relays and bypassing the trigger switch on both my rifles soon, I just cant see those small contacts passing as much current as I've measured before ;)
« Last Edit: December 31, 1969, 05:00:00 PM by Phreakish »
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Offline LiquidSky

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« Reply #8 on: April 10, 2006, 10:32:02 PM »
in 8+ years and the massive amount of rounds i have put down range with an airsoft weapon, i have yet to necessitate a switch relay, fuse or FET. i've used 14.4 volt batteries on specific weapons and still haven't melted a trigger assembly. is this where the concern lies? i may have misinterpretted what is being asked but it seems like there is a worry over somethign that is highly unlikely.

but what do i know? you guys might be using 24 volt, lead cells at 1800 RPM. booyah.
« Last Edit: December 31, 1969, 05:00:00 PM by LiquidSky »
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Offline Phreakish

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« Reply #9 on: April 11, 2006, 02:26:41 PM »
Twice I've had 'failures' in the trigger switch contacts where the intial current caused an arc that welded things together that the spring couldn't pull apart (this just recently happened inside my M14 also).   Its just added security and shoudl work better IMO.
« Last Edit: December 31, 1969, 05:00:00 PM by Phreakish »
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