Introduction to the MOSFET

The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is widely used on many electronic devices as switches. For the case of the water gel blaster it is used for regulating the electrical circuit and programming the blaster to do several things that would be impossible to do otherwise. In other words you could say that installing a MOSFET is akin to adding an electronic brain (Electronic Trigger System) into your blaster.

So why do you need a MOSFET in your battery powered gel blaster? Mainly to protect the trigger switch. How? Simple, with the usage of a high voltage battery, the trigger contact will deteriorate and eventually goes kaput, this is mainly due to the lack of regulation of the electrical current going through the circuit. When the trigger is pulled and the trigger switch trolley is pushed to the switch to complete the circuit, an electrical arc will form which will burn the trigger contacts causing deterioration of the contacts over time. Google “Electrical Arcing and why it is bad” if you need to know why it’s bad for your blaster.

When a MOSFET is installed, it essentially completes the circuit by default, replacing the traditional mechanical trigger switch and bypassing it. The trigger switch now instead acts as an electronic signal provider to the MOSFET telling the trigger is now pulled and starting the operation of the gearbox. 

Most MOSFET nowadays comes with low battery voltage protection as it will not allow the blaster to function once the battery is drained near the nominal voltage to protect it from being over discharged. An added safety feature to help preserve the Li-Po battery lifespan.

A MOSFET typically also comes with the Active Brake function. Active Brake is a feature that stops the motor from spinning immediately after the trigger is released. This Allows the gear system to work with perfect precision with every single trigger pull. This eliminates the “burst” or “full auto” issue in Semi-auto commonly found with stock gearbox using 11.1v battery and will give a super snappy semi-auto firing.

The trigger response will feel really tactile and awesome to pull since the trigger switch mechanism is now replaced with a microswitch that is more clicky. With that there isn’t much of a waste of energy and your blaster will work more efficiently. 

Furthermore some MOSFET are programable meaning that you can customize your blaster firing modes such as the 3-5 burst fire, Turbo Shot (double firing on the trigger pull and release action). Enabling you to have an advantage in CQB or SQB matches that don’t allow Full Auto. But of course this is all subject to change with the competition’s rules and regulation.

MOSFET for gel blaster also comes in different types or manufacturers but typically they utilize either Magnet or Optic sensor to work with the system.



It replaces the mechanical trigger contacts completely with an electronic microcontroller switch.

It replaces the mechanical trigger contacts completely with an electronic microcontroller switch.

Uses magnet to detect the position of the Sector gears

Uses a light sensor to detect the position of the Sector gear.

Has magazine contacts pre-installed

Doesn’t have magazine contacts pre-installed

Battery connector is pre-installed (mini Tamiya)

Requires you to solder a battery head connector

Easy to replace with no need of soldering

A bit of a hassle due to need to solder connectors

Cons of the MOSFET 

While it is great that you won’t have to worry about the arcing in your trigger contact and plenty of additional programmable features, there are some disadvantages of having a MOSFET. One of them is that when the MOSFET goes kaput, the blaster will cease to work and you need to replace the entire MOSFET unit, which is pricier than replacing the traditional mechanical switch. 

The other disadvantage of MOSFET is that it will constantly drain your battery as long as it is plugged in due to the nature of how it works. Meaning your Li-Po battery will be continuously drained dry and will fail prematurely if a battery is left plugged in for an extended period of time. So you should always remove the battery once you stop using it, which is a good practice regardless if your blaster has a MOSFET in it or not .

With the disadvantage out of the way, here’s one piece of good news. The newer generation of MOSFET such as the BR MOSFET is made to be very user friendly and you can replace them very easily without the need of any special tools or even a soldering iron. With the features offered by the BR MOSFET, it is certainly worth having it in your gearbox. Consider it a wear and tear part and you are guaranteed to love it!