MOSFETs & Electronic Trigger Units

Why fit a MOSFET

In a stock AEG the trigger contacts switch the full motor current, which arcs and pits them, and an 11.1 V LiPo makes it worse within a few games. A MOSFET lets the trigger send a small signal while the transistor carries the load, so the contacts last and the motor gets the full voltage with less loss. Active braking stops the motor at the end of each cycle, which prevents overspin and double shots on semi-auto. A simple MOSFET is the cheapest reliability upgrade for any gun running a LiPo battery.

Electronic trigger units

An ETU replaces the trigger contacts and often the cut-off lever with an optical or micro-switch board inside the gearbox shell. It adds programmable modes: burst, pre-cocking for an instant first shot, adjustable trigger sensitivity, rate-of-fire control and low-voltage protection for the battery. Some units read the cycle with sensors and detect jams. ETUs are designed per gearbox version, V2 and V3 mostly, and per shell generation, so use the gearbox version and compatibility filters and read the fit notes carefully. Brushless motors need an ETU that supports them.

Wiring and connectors

Low-resistance silver-plated wire, Deans or XT60 connectors and a clean solder joint matter as much as the board. Wiring harnesses for front and rear-wired guns are listed under the type filter. Electronics are unrestricted parts, and a build usually goes with new internals from gearbox and internals.