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How to Install a Mosfet Airsoft – Step-by-Step Guide

How to Install a Mosfet AirsoftOnce you find out about the benefits of using a mosfet transistor for your AEG, the natural reaction is to want to learn how to install a mosfet airsoft component into your automatic electric gun.

That way, you can upgrade to a more powerful battery and protect your AEG trigger contacts from eventual damage. You may even improve the trigger response and boost the rate of fire.

For those who wish to customize their AEGs with optimal features, the mosfet is a must.

The main problem is that installing a mosfet into an AEG isn’t as simple as putting in a new magazine into a rifle.

The good news is that it really isn’t all that hard. If you have the money, you can even have the job done for you by a pro.

DIY or Paid Technician?

Using soldering iron to fix a connector FreeInstalling a mosfet airsoft unit involves some rewiring, and maybe even some soldering.

If it’s been a while since you’ve done some soldering, you may review a soldering guide to help remind you of what to do.

If soldering is too complicated or too bothersome for you, then you may want to go with a paid airsoft technician instead.

The same goes if you’d rather not deal with the wiring yourself.

At least with this guide, you can check out how it’s done and you can verify the work.

Also, the next time you need a mosfet installed then you can do it yourself, once you’ve seen for yourself how it’s supposed to be done.

To find a competent professional airsoft technician to do the mosfet installation, you can go online and get in contact with local airsoft groups.

Some of these local airsoft groups are on Facebook. Just ask them for anyone who can do the work, as they may know some reputable pros who can help you.

Assembling Your Work Equipment

Top view circuit reparing tool Before you start installing the mosfet unit, find a place with a proper working surface with sufficient lighting.

Then gather the things you’ll need:

  • 40-Watt soldering iron
  • Screwdriver
  • rosin core electrical solder
  • wire clippers and strippers (preferably a 16-ga and a 22-ga)
  • small lighter
  • heat shrink tubing
  • extra wiring
  • low resistance connectors like Deans or the XT60
  • flux pen
  • other tools needed to take apart your airsoft gun
  • containers where you can put your AEG screws
  • notebook and pen to note how many screws you’ve taken out from various places

Additional Notes

Write down the steps you take when you disassemble the AEG

It’s not uncommon for anyone to disassemble an AEG, and then after reassembling you end up with extra screws. By taking notes about how many screws you take out from where, you should be able to put them all back in.

Read the installation guide for your particular mosfet unit

Not all mosfets are the same. You need to find out which of the mosfet pads are for the trigger, the motor, and the battery.

Determine where in the AEG you’ll put the mosfet.

Keep in mind that AEGs aren’t all the same, so you need to decide where it’s optimal to connect all these wires.

The good news is that lots of mosfet units are small, so you’ll have plenty of options regarding its placement.

Cut the wires short

For the trigger contact, you don’t really need thick wires. You only need the high-current wires for the motor and the battery.

You do need to remember that shorter wires are better, because the shorter length reduces electrical resistance.

Most of the time, the mosfet comes with longer wires that you have to cut to the right size.

So measure several times to make sure you get the right length. Then test fit the mosfet unit, to really make sure you don’t end up cutting off too much of the wire.

Shift to low-resistance

You can optimize the performance of your AEG by replacing the wiring in your airsoft rifle with a low-resistance wire.

The same goes with your connectors, especially if your AEG has mini-Tamiya connectors. These connectors are high-resistance, and are not meant to deal with the high currents doled out by more powerful batteries.

That’s why you need the low-resistance connectors such as XT60 and Deans.

The Step-by-Step Mosfet Installation

Programmable for AEG Airsoft Electric Rifles Sniper Pistol Guns Accessories Compatible with Airsoft Battery LipoNow that you have your equipment and your preinstallation notes, you can start. Just take your time, and be careful.

  • Disassemble the gun: Again, take notes regarding the process, to help you reassemble the AEG afterwards. What you don’t want is to “finish” the reassembly with still some extra components (such as screws) left.
  • Extract the gearbox: If you don’t know which part that is, go online and Google your AEG model to see what the gearbox inside looks like.
  • Recheck the installation instructions for your particular mosfet unit.
  • Solder the thin wires to the trigger contacts.
  • Add a heat shrink tube for every connector. You may want to use a longer tube to manage and protect the wiring.
  • Solder the wires to the Deans connectors. This is the tricky part. The wire and connector need a lot of heat to solder properly. You may want to use a heat resistant mounting for the connector, and use pliers to guide the wire.
  • Crimp the female spade connector on the motor wires and add a heat shrink. The other option is to solder the wires directly to the motor. This isn’t a good idea though, since you can end up overheating the connectors.
  • Apply tin to the mosfet pads.
  • Solder the battery wires to the mosfet battery pads. You should find labels like BAT+ and BAT-, or even just B+ and B-. The general rule is that the black wire is negative, the red is positive.
  • Solder the motor wires to the motor pads.
  • Now solder the trigger wires to the mosfet trigger pads. In some cases, there’s just a single pad for the trigger. You’ll then need to solder the 2nd wire to the BAT+.
  • Recheck that you’ve soldered all the wires to the right parts. If you soldered the wires the wrong way, when you use the AEG you’ll end up ruining your mosfet.
  • Test the mosfet before reassembling the gun. To do this, connect the motor to the circuit and then the battery. Use a vice to hold the motor tightly, and then pull the trigger. When you pull the trigger, the motor should come to life.
  • Wrap a large heat shrink tube over the mosfet.
  • Reassemble the gun with the mosfet, and test it again.

You’re done!


It’s true that you can save yourself all the fuss and just let a pro handle it.

Of course, there’s always the chance that the “pro” you get is just winging it, so you should still be familiar of what the task entails.

It may help if you go online and look for “airsoft mosfet installation” on YouTube. You’ll find lots of videos on this topic, and it should give you a nice overview.

If you’re lucky, then you can also enter the type of your mosfet unit and the type of AEG you have and find a YouTube video demo that features both your mosfet unit and your AEG model.

All we can say is that despite the seemingly complicated nature of the task, it’s not really as hard as it seems. Take some care, and you really can do it yourself.

Learning how to install a mosfet airsoft will give you a much better weapon, and that’s always satisfying!

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