I get alot of questions about Mosfets rewiring etc etc. So i decided to put together a guide to help clear up some common issues people might have and to show how to make your own mosfets capacitor banks etc etc.
WIRE SELECTION!
There are many different wire types, all of which have advantages and disadvantages. Here are the main types you should consider using in your AEG.
Solid Wire
Pros - Very thin
- Low resistance
- handles more amperage than comparable gauge stranded wire
- very stiff, easy to route through gearbox and such
Cons
- breaks easily
- very stiff, can be bad in some cases
Hook-up Wire
Pros - pretty flexible
- thinner than silicone wire
- easy and cheap to come by
- tough insulation
Cons
- 16ga wire sometimes too thick for Ver 2 gearbox
- not the top performer in low resistance and amperage rating dept
Teflon coated mil-spec wire
Pros - Standard OEM wire in Systema, Prometheus, and Tokyo Marui
- Very Strong insulation
- Super thin, 16awg teflon wire is thinner than any other 16awg wire
- typically has silver coated copper conductor
- low resistance
- pretty stiff, routes easily through gearboxes and aeg bodies
Cons
- pretty stiff not as forgiving if you measure out the lengths wrong
- expensive
Silicone wire(deans wet noodle)
Pros - very low resistance
- very flexible
Cons
- very expensive
- silicone insulation tears very easily
- hard to solder
- extremely thick
Speaker wire
dont use it unless you have to.
Wire size
Wire size is typically measured in teh American Wire Guage system. In this system the smaller the #, the larger the wire. The Guage is determined by the size of the CONDUCTOR only and not the overall size if the wire.
Most AEG's come with 18 or 16 AWG wire. 16awg wire is best for most AEGs since it handles 75 Amps. If you have room you may try 14awg but the benefit will be minimal.
Connectors
Tamiya(large and small)
These connectors suck ass. they are worn out after about 50 cycles of being put together and pulled apart.
They are also a huge source of resistance and allow a mere 15amps or so to pass through them
Deans Ultra plugs(T-connectors)
Last a long time and can handle alot of power as they are very low resistance.
Switch to these connectors right away!
typically 10 pairs can be had on ebay for $4!
To add deans plugs is simple.
*Cut off worthless Tamiya Plug (if this is the battery , be sure to only cut one lead at a time to avoid short circuit.)
You can also clamp the deans plug in a vice or clip to hold it while soldering at this time
Typically the battery uses the female end and the male end goes to the AEG harness
* Now pretin each of the deans plug terminals. Do this by adding a bubble of solder to each of the terminal tabs.
*Next put a piece of heatshrink on each wire to be soldered. Then attach the + wire to the vertical tab, and the - wire to the horizontal tab.
Should look like this.
Then heat the shrink tubing to cover the exposed terminals!!
The video shows how to do this as well.
Tools
-soldering iron/irons
-wirestrippers
-heatsink
-voltmeter
-wet cellulose sponge
-sandpaper
-flux
-helping hand tool
-heat gun
-glue gun
-pliers
Capacitor BAnks
Capacitor banks Can improve your trigger response and rate of fire.
Electrolytic Capacitors store energy and release it on demand. This will fill in voltage drops seen when you initially pull the trigger, and when the AEG is cycling through some shots.
When the voltage drops, the capacitor releases its stored energy and helps smooth out the current. once the voltage drop is gone, the capacitors fill up once again.
The improvement is nominal though, and to get a noticable difference you need a pretty large bank. Not all AEG's have room for this so keep that in mind.
If you can fit them in though, there really is no disadvantage to using them.
to install a capacitor bank is simple. Just find a suitable location for them, and solder them in paralell into your aeg wire system.
They are polarized so get the +/- correct. The (-) side is shown by having a stripe running down the cap on one side
I usually make my capacitor banks removable so i can switch them from gun to gun.
You can buy capacitors at radio shack, from an online store, or in old unused electrical devices such as disposable flash cameras.
here is a schematic
FUSES
Fuses come stock in most AEG's. They heat up and break the circuit when there is an over load of current. I typically don't run any fuses in my AEG's since i can rewire one on 15 minutes. but if you are concerned about your setup, here are some fuses.
glass or plastic automotive fuses
these are found in most stock AEG's. when they trip, you just pop in a replacement.
polyfuses(resettable)
These fuses gradually expand when heated to the point where they no longer conduct electricity. Once the current is removed, they contract and cool to the point where current can flow again. Once they trip however, they are tripped again very easily unless given sufficient amount of time to cool.
Glass fuse and a Polyfuse
Motor connectors
There are three main options here.
good
standard motor connectors - not the best because of high resistance.
better
gold plated motor connectors - allow more contact between connector
and motor tab which decreases resistance
Best
Solder wire directly to motor tab- best option but must desolder every time motor is removed(sux for ver2 GB owners)
Mosfets
A mosfet is a switching transistor that can handle high loads and carries very little internal resistance. There are many benefits to using these and there are really no drawbacks to using them.
-They can do these great things...
- increase ROF
- Allow use of higher voltage batteries
- save your trigger contacts from ever burning up
- increase trigger response
- increase overall efficiency of your electrical system
It is really easy to make one if you have some soldering skills. (watch the video for some soldering tips.)
Here is a good soldering guide that i had nothing to do with making...
http://www.kpsec.freeuk.com/solder.htm
Here is what you need to make the Mosfet unit itself...
100ohm resistor
20-30k ohm resistor
suitable mosfet ( I always use IRL1404z)
You may also want to find plenty of heatshrink tube in various sizes and the wire that you are going to use for the motor and for the gate wires.
The Mosfet has three pins. Gate , Drain , and source.(see first picture)
You need to put the 100 ohm resistor on the gate pin, and the 20-30k ohm resistor(pull down resistor) between the gate and source pins.
I like to cover the mosfets heatsink with heatshink tubing. I do this because the heatsink has the same electrical value as the drain pin, and i don't want anything to short out by touching it.
I also cover the pulldown resistor.
First i attach the pull down resistor...
and then the gate resistor ...
After that you are good to get started. rewiring. First you must desolder the trigger contacts and attach the gate wires. I typically use the small wires found inside of ethernet cable.
Desolder each trigger contact and attach a gate wire to each of the trigger contact tabs. it should look like this.
then you can add new wires that go straight from the battery to the motor.
No all you need to do is find a spot to put the mosfet. When you find it, clip the negative wire in half and take the side that runs to the motor. attach this side to the center pin of the mosfet(drain pin)
then attach the other end of the negative wire, the one that goes to the battery, to the outer "source" pin.
Then finally attach one gate wire to the gate resistor on the mosfet, and the other gate wire needs to be spliced somewhere into the positive wire.
Bam you have a mosfet system!
P.s. quick pictographic diagram
Wait what about active braking?!?!?
Ok that's easy too. All you need to do is add a p-channel mosfet.
The benefit of active braking, is that the motor will "brake" or stop as soon as you let off the trigger.
This helps the piston stay forward and avoid putting stress on the gears and such . It also makes for an amazingly crispy trigger pull.
The guys at
www.airsoftmechanics.com pioneered all of this, and made up schematics for us to use! Props to Gandolf(Terry) and PsypherVII.
There are many ways, even some better ways to do this. But here is how i do it, and it works.
Here is a n-channel and P-channel mosfet. I start by glueing them together back to back.
here it is...
Then i bend the P-channel's gate pin to meet up with the N-channels gate pin.
Then i bend both drain pins(center pin) together and solder them as well...
then I add the pull down resistor between the n-channel's gate and source pin as usual.
and finally add the gate resistor(100ohm) to the N-channel mosfet's gate pin.
Now You simply wire this in the same as you would a standard mosfet. The only difference is, you need to take the p-channel mosfet's source pin, and splice it into the positive wire. (see diagram below)
Here are some active braking mosfets in various stages of development...
Aslo here is a video Guide on how to rewire and AEG with a mosfet...!
*** VIDEO ***
http://s7.photobucket.com/albums/y284/meancivicsi/airsoft/?action=view¤t=MOSFETPART1.flv
http://s7.photobucket.com/albums/y284/meancivicsi/airsoft/?action=view¤t=mosfetpart2.flv
WHERE TO GET PARTS!
www.digi-key.com
n-channel mosfet search part # IRL1404ZPBF-ND
p-channel mosfet search part # SPP80P06PIN-ND
polyfuses'
MF-RHT650-ND(use two in paralell)
MF-RHT750-ND(use two in paralell)
Radioshack and Fry's have resistors and capacitors of all kinds as well as digikey
Ebay has all kinds of parts and wire! Use it ! Don't be scared!
references
-www.airsoftmechanics.com
-www.digi-key.com
). It normally costs me about 1/3rd of the price it cost to buy one ready assembled and about the same time to install it as it would to install a pre made one aswell.
