MOSFET Installation Instructions

This article will explain how to install our High Current MOSFET.

If you are new to soldering or would like a refresher, please see our Soldering Guide.

First, you must decide where in the gun your MOSFET will be. The High Current MOSFET is very small so you have a lot of options. It is a good idea for the wires to be as short as possible to reduce elctrical resistance, so bear this in mind when placing the MOSFET. It comes with plenty of wire which is designed  to be cut to the correct length. Measure several times, and test fit the MOSFET to make sure you don't cut off too much wire.

We recommend replacing the entire wiring system in your AEG with the wire that comes pre-solderd to the MOSFET. This reduces the number of solder joints therefore reducing resistance. If you need to keep some of the existing circuit  in place, you can splice the MOSFET wire into the existing circuit as long as you are careful to make good solder joints.

The MOSFET comes with 6 wires pre-soldered to it. The thicker (16AWG) wires are polarised: Red is positive, black is negative.

From one end there are 2 wires - these are the battery wires.

  • If your MOSFET has a fuse, you can solder the battery wires directly to your connector of choice. 
  • If your MOSFET does not have a fuse, you should solder a fuse to the positive wire (red) as close to the battery as possible. Placing it close to the battery means that the fuse can protect more of the circuit. It is not recommended to use an AEG without a fuse, especially if you are using a LiPo which can fail violently under a short circuit, potentially causing a fire.
  • With a fuse in between the MOSFET and battery on the positive wire, you can now solder your connector of choice to the battery wires.
  • Low resistance connectors such as Deans, XT60, Traxxas or gold bullet connectors (at least 4mm diameter) are recommended. The stock mini Tamiya connectors that come with most AEGs are high resistance and should be replaced.

From the other end of the MOSFET are 4 wires - These are the motor wires and trigger wires.

  • The motor wires are thicker than the trigger wires. They should be soldered directly to the motor connectors.
  • The trigger wires should be soldered to either side of the trigger switch. When these two wires make contact, the gun will fire.
  • Once all the soldering is done, you should check that all the wires are soldered to the correct parts. You can destroy the MOSFET by plugging it in the wrong way, so it is worth double-checking the connections at this stage.
  • You should test the MOSFET before fully re-assembling the gun. This can be done by connecting the motor to the circuit, then the battery. Hold the motor tightly by hand or in a vice, then pull the trigger. The motor should come to life as soon as the trigger is pulled. If so, reassemble the gun and test again. If it works normally, congratulations, you have successfully installed your High Current MOSFET!

If nothing happens when you pull the tirgger, check again that the wires are soldered to the correct parts. If so, there may be a problem with the motor. You can connect the motor directly to a weak battery to see if it is working normally.

If the motor is fine and the MOSFET wires are soldered correctly, then check each solder joint to make sure it is not ‘cold’. A cold solder joint looks dull and tarnished, and does not conduct electricity well.

If you have ruled out the motor and wiring, you may need to send the MOSFET back to us for inspection. Please get in touch.