Helpful Guide to Airsoft Motors and MOSFETs [Airsoft Essentials]
What is a motor and what does it do?
All contemporary airsoft AEGs use a mechanical system inside their gearbox that contains a combination of three gears and a motor to allow a smooth transfer of electrical energy into mechanical energy. This process begins with a simple trigger pull which in effect results in trigger contacts closing and completing the electric circuit from the battery to the motor. The motor then receives power to begin spinning and engages the first (bevel) gear.
In other words, when the trigger is pulled and the battery sends electricity to the motor, it is then responsible for initiating the movement of the gears inside the gearbox which subsequently results in the replica shooting. Therefore a motor can dictate the rate of fire and the responsiveness of semi-auto. We’ll discuss how to upgrade later on in this article.
Note: there are two sizes of motors: long and short. Before you purchase a new one, double check your replica’s manual which type is installed as stock!
Where is it located and how to adjust it?
The main power source for the repeat action in your AEG replica is held by you at all times. The motor is located in the grip and it is fairly easy to be replaced and adjusted.
At the bottom of the grip (image below) you’ll find a cover with two smaller screws and one large central screw. The large flat screw is there for you to adjust the motor position so it engages the gears in gearbox in a perfect position.
For example, if it’s too tight, thus the motor is too high in adjacent to the gears, it might cause drops in FPS and increased wear and tear. On the other hand if it’s too loose, thus the motor is too low in adjacent to the gears, it will simply fail to grab the gears and rotate the gearbox.
Two smaller screws hold the bottom plate together and, once unscrewed, will reveal the bottom of motor along with connecting cables. These can be unplugged and once done, the motor can be removed easily and safely.
(Remember to put red and black wires correctly so the rᎥfle doesn’t shoot backwards!)
Why replace the stock motor?
Well, there’s two reasons. A better motor can either increase your fire rate, or the responsiveness of your semi-auto shots. If properly paired with an appropriate gear ratio, it can do both. Subsequently, there are two routes you can take when deciding on a new motor:
High Torque Motor
High torque motor is made to spin up to its maximum RPM in the fastest way possible. That means when you press the trigger there will be very little delay before your BB will be fired. Very responsive and beneficial to those players who use semi-auto feature often or exclusively.
High Speed Motor
High speed motors are quite different as they spin up to higher speeds enabling much higher fire rate. However, the downside is they take a split second longer to spin to maximum RPM resulting in a slight delay on the first shot. Perfect for people who want to annihilate opponents with hundreds of BBs at a time.
However, to fully take advantage of a new motor, you’d be a fool not to use a 11.1v LiPo battery with a higher discharge rate, such as 25c, to produce best results. Which brings me to MOSFETs and why are they necessary if you don’t want to burn your trigger contacts when using such batteries!
Recommended motor brands
Make sure the read each product’s description and see whether it’s capable of pulling the spring you have inside your replica – look for descriptions such as: “Application: M90~M170 spring / 280~550 FPS output gearboxes.” Also there are both Short and Long types – make sure to double check your replica’s type of motor before purchasing one!
What is a MOSFET and why is it important?
MOSFET is an electrical component that redirects the electricity to go directly from the battery to the motor without ever touching the trigger contacts.
When using higher discharge and voltage batteries without a MOSFET, such as a 11.1v LiPo 25c, the high discharge rate will slowly damage the trigger contacts as it passess through them. So how can we avoid that? Here’s an example:
Without a MOSFET
As mentioned before, a motor has two wires – one is positive and the other is negative. If the replica doesn’t have a MOSFET installed, the positive wire will send electricity through the trigger contacts first, then to the positive side of the motor. The negative current goes directly to the motor regardless of the MOSFET.
With a MOSFET
Wiring a MOSFET into the gearbox adds two new wires called ‘signal wires’. When the trigger is pulled, a signal gets sent to the MOSFET through those wires, which then activates the MOSFET sending a direct electricity current to the motor from the battery. This eliminates any electricity passing directly through the trigger contacts.
Note: Mosfet is not necessary when using NiMh batteries or 7.4v LiPo, but it will increase the longevity of the internals.
Recommended MOSFET brands
Other Benefits of MOSFETs
Advanced MOSFETs such as Gate Titans, allow you to manipulate a variety of aspects in your replica, such as: altering the fire rate, precocking the spring or changing to burst mode all on an App in your phone! Click here to see their product range on their official website!
How to install a MOSFET?
There are two versions of MOSFETs if you would like to install one in your replica. There’s the drop-in-kit which goes inside the gearbox and the Nano which goes in the stock tube. Both will require soldering and rewiring the replica.
We thoroughly recommend sending the replica to a technician for a MOSFET installation, unless you have experience in electronics. Here’s a useful video on how to install the drop-in-kit from Gate Titan:
This article is part of AR Wiki, please click here to see the master article written by us.
I hope this article has cleared any confusion that you might have had and will help you in your Airsoft journey! If you think we missed something out, please feel free to comment or start a new thread in our forum!
All the best Ranchers!