Gel blaster MOSFETs: what they actually protect (and what they're worth used)

October 31, 2026 By Patrick Amadeu

Quick Answer: On a stock gel blaster, the trigger is a pair of metal contacts that switch the full motor current every time you pull it. Each pull makes a small spark, and over time the contacts pit and burn, especially on an 11.1V LiPo. A MOSFET is an electronic switch that takes that current off the contacts, so the trigger only sends a tiny signal. That’s the job that matters. Programmable MOSFETs add active braking, burst modes and battery protection. Full electronic trigger units, like the Leviathan in my builds, replace the trigger contacts altogether. On a used blaster, “has a MOSFET” means little until you know which one.

Inside the gearbox series: 1. Gearbox noises · 2. Motors · 3. MOSFETs · 4. Wiring and plugs

Both my main blasters, an MK18 and a Noveske N4, run a Leviathan. When people ask why, the honest answer is all three reasons at once. The trigger is crisper, especially on semi, which is how I play. It protects the trigger and the battery. And it was CyberTrigger’s pick for the build, which counts for a lot with me, because they’re the shop that rebuilt my first rifle after its gearbox came apart.

You don’t need a Leviathan to get the main benefit, though. You need to know what a MOSFET is actually protecting.

What a MOSFET protects

Two wiring diagrams side by side. On the left, a stock gel blaster: the full motor current runs from the battery through the trigger contacts to the motor, and a spark forms at the contacts on every pull. On the right, with a MOSFET: the full current runs from the battery through the MOSFET to the motor, while the trigger only carries a small signal to the MOSFET, so the contacts no longer spark — Left: the trigger contacts switch the whole motor current. Right: a MOSFET does the heavy switching and the trigger only sends a signal.

Without a MOSFET, every trigger pull makes and breaks the whole motor circuit by touching two bits of metal together. At the moment they meet or part, current jumps the gap as a small spark. Repeat that a few thousand times and the surfaces pit and blacken. Pitted contacts have more resistance, so they get hotter, so they pit faster. That’s why a blaster that fires every time when it’s cold can start missing after a couple of mags.

The load is bigger than most people think. AirsoftLab.eu measured a stock motor in a V2-type gearbox drawing around 50 amps for an instant as it spins up, and 12–16 amps while firing on auto. A high-torque motor pushed the spin-up past 60 amps (motor current). Without a MOSFET, every one of those amps goes through the trigger contacts.

Three products sold under one name

Basic MOSFET. An electronic switch, nothing more. The trigger contacts stay, but they only carry a signal. It’s the cheapest way to protect the trigger.

Programmable MOSFET. The same protection, plus features set by an app or programming card: active braking, burst modes, rate-of-fire limits and often a low-battery cut-off for LiPos.

Electronic trigger unit (ETU). Replaces the trigger contacts altogether. JeffTron’s instructions for the Leviathan V2 optical say to remove the trigger, cut-off lever, trigger contacts and trigger block, because the unit uses optical sensors and its own switch instead. It adds an electronic fuse, monitors current, voltage and temperature, and warns on low battery for 2S to 4S LiPos. It ships with 16 AWG Teflon-insulated power wire and a T-plug (Deans-style) connector.

Two Leviathan features are worth knowing about on any used blaster. Active braking stops the gears so the spring is fully released after each shot, which JeffTron says keeps the gearbox parts out of strain and stops extra shots on semi. Pre-cocking does the opposite, holding the piston partly back for a faster first shot, and JeffTron itself warns that it “increases wear and tear on the gearbox”. Ask whether it’s switched on.

🟣 A MOSFET is worth $49 on a shelf and far more in a blaster

What RedSpear’s sales say about MOSFETs, for buyers and sellers.

An eShooter Kestrel V2 Bluetooth MOSFET sold on RedSpear for $49. It took 144 days, the slowest sale in our records. On its own, a used MOSFET is a hard sell. Buyers can’t test it, don’t know its history, and would have to pay someone to install it.

Installed and named, it’s a different story. “Leviathan V2 fitted by a tech, active brake on, pre-cocking off” tells a buyer the trigger is protected and the gearbox has been looked after. “Has a MOSFET” tells them nothing they can check.

Selling: leave it in the blaster and name the exact model in the listing. Buying: ask for the model and look it up. A named, programmable unit on a LiPo build is real value. A mystery board might just be a burst module.

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Do you need one?

Yes, if you run an 11.1V LiPo. Higher voltage means bigger sparks at the contacts. Both my builds run 11.1V on Deans plugs, and both have a Leviathan.

Yes, if you’ve upgraded the motor or spring. More load means more current through the trigger.

Not yet, if you’re on stock NiMH and playing casually. Sort your gel, hop-up and battery first (upgrade order).

Installing an ETU like the Leviathan means working inside the gearbox, and JeffTron warns that it “requires advanced technician skills”. A wiring mistake can damage the board or the battery. This is a job for an approved Queensland tech.

Frequently asked questions

What does a MOSFET do in a gel blaster?

It switches the motor current electronically, so the trigger contacts only carry a small signal and stop sparking and burning. Programmable versions add active braking, burst modes and battery protection.

Do I need a MOSFET with an 11.1V LiPo?

It’s strongly recommended. Higher voltage means bigger sparks at bare trigger contacts, which wear them out faster.

What is active braking?

The MOSFET briefly brakes the motor after each shot, so the gears stop with the spring fully released. It reduces strain in the gearbox and stops extra shots on semi.

Is a used blaster with a MOSFET worth more?

If it’s a named, properly installed unit, yes. Ask for the make and model. On its own, a used MOSFET is a slow seller: one sold on RedSpear for $49 after 144 days.

Sources

JeffTron - Leviathan V2 optical, gel blaster version: functions and specifications
AirsoftLab.eu - Motor current measurements (oscilloscope, V2-type gearbox, 11.1V LiPo)
RedSpear Armory Shopify sales data, May–October 2026 (used items, with days from listing to sale)

Last checked: 31 October 2026. General information. Have a tech install MOSFETs and trigger units.

Looking for a protected build?

Browse used rifles and ask which MOSFET is fitted. Got spare boards or a build to sell? List free and name the exact model.

Read next: Wiring and plugs · LiPo vs NiMH · Gearbox noises

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Written by Patrick Amadeu

Founder of RedSpear Armory and a critical care paramedic since 1989. I’ve played indoor at Blacksite and the former GelSoft Yatala, and outdoor at Donnybrook, Kooralbyn and Bundaberg. RedSpear exists because my first rifle’s gearbox died four days after the shop’s warranty ran out. More about me

RedSpear Armory — Queensland's dedicated marketplace for used gel blasters. Browse listings, sell your gear, and connect with the local QLD community at redspeararmory.com.au.

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