MOSFET Advice - please help

[Henners]

Hi all

 

I'm looking to fit MOSFETs to various AEGs:

 

G&G G2010

Cybergun FAMAS F1

Ares (2013) TAR-21

ASG Steyr AUG Para

PTS Magpul PDR

ICS L85 A2

G&P M4  Special Forces

Matrix SR25K

 

I have no experience with MOSFETs - please could you give me your recommendations as to the best/most appropriate, and any additional points to consider regarding these?

 

Many thanks in advance

 

Henry

[Iceni]

The most important bit is the soldering iron and the connectors you plan to use.

Since you will be re-wireing in most cases it's an opportune time to move to deans connectors. To efficiently solder deans you need a soldering gun rather than an iron.  And some way to hold the connectors as they get hot. A decent flux, and decent solder are also a bonus.

Machine mart sell a kit that isn't as cheap as some of the Ebay deals, but it does have everything in it for deans.

https://www.machinemart.co.uk/p/csk100-universal-soldering-kit/

The holder with the crocodile clips will hold the deans and wires, the soldering gun will give you the heat, there is also a pot of reasonable rosin flux and some solder.

I would add 63/37 eutectic solder to the shopping list as well. It's a specific alloy that goes from liquid to solid without the mushy phase of 60/40 and lead free solders. It also melts at a decent low temp, Lead free needs more heat, and will make you cook the connectors.


You will need deans connectors, and a good supply of heatshrink tubing. Ebay  is the best place for heatshrink, you can buy a box of multiple sizes and colours cheap enough. And having the right heatshrink will improve the life of any loom you make. And most importantly it will give you the best protection against shorts and look the most professional when done.

https://www.ebay.co.uk/itm/400X-Heat-Shrink-Tubing-Tube-Sleeve-Kit-Car-Assorted-Electrical-Cable-Wire-Wrap-/273157170719?_trksid=p2349526.m4383.l4275.c10


The wire is your choice, but I've had good results from the silver plated type. AK2M4 sell this cheap compared to most shops that are double the price.

https://www.ak2m4.co.uk/internal-parts/misc-internal-parts


For the actual units themselves you have a lot of options. AK2M4 again off some of the cheapest I have seen if all  you want is basic protection.

https://www.ak2m4.co.uk/internal-parts/mosfets

The Xcoretech x304u is also a cheap well respected unit for basic protection that follows the same design idea as AK2M4's. I have one of these in one of my augs and it fits without a problem in the space behind the gearbox plate.


If you want active braking or circuit protection then Gate make some very good fets. Expect to pay more for them, but models like the Gate Nano hard offer on/off active braking, and user definable circuit protection. Again I have one of these in an AUG but it required significantly more work to get in, And I had to cut the gearbox plate.




V3 gearboxes can be fetted without opening them. It's as easy as cutting 2 wires and soldering some longer leads in place to the fet.

V2 gearboxes have to be opened. You need to route in the signal wires and change the motor wires, so V2's are significantly more time consuming, and it is worth totally replacing the loom in most cases.



 

[Sitting Duck]

Excellent post sir

 

Only thing to add is that you can make your own 3034 mosfet

Buy 10 or so from Farnell & price drops to £1:77 so with some other bits n bobs a 3034 is about £2:50 to £3

 

http://uk.farnell.com/infineon/irlb3034pbf/mosfet-n-ch-40v-195a-to220/dp/1698299

 

Make up a few at a time as OP has a few guns to install

I mean if you are soldering trigger wires, deans & what not - a 3034 is no biggy tbh

loads on google: diy airsoft mosfet thingy.....

 

http://unconventional-airsoft.com/2009/08/26/how-to-make-a-basic-mosfet-switch/

 

TVS diode I use is this one I think:

http://uk.farnell.com/stmicroelectronics/1-5ke18a/diode-tvs-18v-1-5kw/dp/9884831

 

Just so happens this is the exact same mosfet used in Krytac's

 

If you was installing just one or two mosfets - yeah buy one off the shelf

but if you are fitting more than a few and can solder OK then a diy 3034 is a worthy consideration imho

 

Don't ffs buy one them DairyLea ones that are made with snide/cheapo china mosfets.....

 

THEY ARE $HIT !!!!!

 

Don't buy 3034's from fleabay either, they are all or nearly all snidey clones that will blow quickly

You buy genuine 3034's from Farnell or RS

 

Where space is really limited then the spaklabs mosfet soldered direct to deans could be a consideration

though I haven't tried these myself.....

 

Alas think Pete has sold out of these but he might get some more soon....

 

pretty clever & neat mosfet install

 

Oh well there are some options to mull over

[Rogerborg]

10 hours ago, Iceni said:

To efficiently solder deans you need a soldering gun rather than an iron.

 

Eh.  I've rewired all my guns and batteries with a 60W iron and Sn 60 / Pb 39 / Cu 1 1mm wire, dab of flux, no problems.

[Iceni]

2 minutes ago, Rogerborg said:

I've rewired all my guns and batteries with a 60W iron and Sn 60 / Pb 39 / Cu 1 1mm wire, dab of flux, no problems.

60W would be fine, Because that is digital soldering station territory. The cheap 15/30W irons are the problem, as the dwell time goes up significantly enough that you will burn deans. It's about getting the heat onto the component as fast as possible so it doesn't have time to spread to the full component. The 100/150W guns are instant touch soldering for deans, no dwell time at all, I have a 60W station as well, but the gun is significantly faster even with big chisel tips.

Your solder is reasonable 60/39/1 is used to prolong the life of soldering iron tips. It's melt point is only slightly higher than 63/37 and it's not quite eutectic. 63/37 is regarded as the best for a few reasons, It's got the lowest melt point 183 celcius, It wets and flows very well, and it's eutectic so no mushy phase, and it leaves a bright solder joint. 60/40 solder is aright, it doesn't' flow easily and leaves dull joints but it's cheap. In contrast lead free mixes will require 220-230 degrees celcius of heat It's almost 50 degrees more heat on the same component.

If you want a challenge pick up some 63/37 and do a few joints with it... See how it compares to the solder you have been using. It will probably surprise you how well it flows and sets.


 

[Rogerborg]

Cheers, I'll give that a try.  I'll disclose that my 60W iron was "cheap", but it does have a functional temperature control and has worked OK so far.

[Iceni]

1 hour ago, Rogerborg said:

I'll disclose that my 60W iron was "cheap", but it does have a functional temperature control and has worked OK so far

There's nothing wrong with cheap provided it works. All it is at the end of the day is just a heat source. I would imagine for the solder you have you have it set to about 200C. Dwell time will be short but you will have a problem with deans wires moving as the solder sets. On smaller stuff it will be no problem at all, it's just deans have enough mass to hold temp a bit longer after the heat.

Moving onto the 63/37 you could drop that temp a little, and have no problems with the wires moving on cooldown, It'll either be liquid or solid, and it'll grab fast on the phase change. Like I say try some and come back with feedback, because the difference is night and day.

 

[Henners]

Thank you for the advice guys, some really useful information here

 

Cheers!

 

Henry

[Rogerborg]

63/37 on its way: I have noticed a fair amount of "mushy" phase with the 60/39/1.  Thanks for the heads up.

[Iceni]

On 5/2/2018 at 2:52 PM, Rogerborg said:

63/37 on its way: I have noticed a fair amount of "mushy" phase with the 60/39/1.  Thanks for the heads up

Did it arrive, and have you had a chance to test it yet?

[ak2m4]

Hopefully have some more MicroFET's soon 🙂