MOSFET or the Metal Oxide Semiconductor Field Effect Transistor is fast getting to be a favourite ­add-on for serious airsoft players. Extreme-Fire is leading the revolution in MOSFET technology, and opening up its source to make it an open source project, which for those who are not into Informa­tion Technology, is a collaboration of individuals who can put modifications into the source code into the project and ability to use modifications without any copyright violation.

This open sourcing is a welcome development in airsoft as many airsoft innovations are now coming from airsoft players themselves, and not only from the airsoft companies.

So what is MOSFET? We'll make Extreme-Fire's information make the introduction:­

What is a MOSFET switch?

A MOSFET switch is a high-power solid state electronic switch that takes the power normally dissipated through the trigger switch assembly and instead routes that power through a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). With this type of circuitry, the trigger switch is only used to send a very low-power signal to the MOSFET switch. The MOSFET switch then turns the current on and off without any arcing or damage to the trigger switch and wear is virtually eliminated and its lifetime is extended indefinitely. Amazingly, the MOSFETs used in Extreme-Fire products could deliver up to 5000 Watts of power to the motor, but no Automatic Electric Gun (AEG) motor will even need that much.

What are the advantages of using a MOSFET switch?

A typical AEG must deal with a current of up to 50 Amps or more every time the trigger is pulled. (Note that electrical switch wear greatly increases in upgraded guns where current reaches 75 to 100 amps!) This very high current causes a standard mechanical trigger switch contacts to arc and burn. MOSFET switches use less than 0.1 Amp of current and totally solve problems associated with electrical wear.

What is Active Braking?

When the trigger switch turns the current to the motor off, the motor continues to spin for a short time due to its spinning momentum. This over spinning tends to compress the piston spring and generally adds to mechbox wear. The problem is far worse for modified airsoft guns that have a high rate of fire can causing the gun to double or even triple fire after trigger release because the motor simply can't stop fast enough. Active Braking (AB) forces the motor to decelerate very quickly by applying a large electrically-produced braking torque inside the motor which quickly brings it to a stop.

Breaking vs. Non-Breaking MOSFET switch

Will it void my AEG's factory warranty?

It is necessary to disassemble the gun and usually the mechbox for installation of MOSFET switches. Disassembly of the gun will usually void the manufacturer's gun warranty.

Will it increase my FPS, ROF, parts durability?

FPS - Normally, there will be no effect on BB velocity.

ROF - Generally, rate of fire does increase some due to lower switching resistance. However, the lower gauge wiring and perhaps shorter total lengths of high current wire used can also have an equal or greater effect on ROF. In general, all one can say for sure it that it will not lower ROF.

Wear - Mechanical wear inside the mechbox will not be affected by non-breaking MOSFET switches other than vastly reduced electrical switch contact wear. Active breaking MOSFET switches may significantly reduce wear by stopping the gear train properly and faster. They also prevent leaving the piston spring in a compressed state during storage. Theoretically, motor brush wear should increase 4% in semi mode and 0 to 1% in auto mode due the added active breaking current.

Extreme-Fire SW-Revolution

There are several products in the inventory of Extreme-Fire, but their latest product is the The Extreme-Fire SW-EVOLUTION which is a fully computerized MOSFET switching system that controls the firing of an AEG.

The Extreme-Fire SW-EVOLUTION is a higher powered version of the SW-COMPUTER with better noise immunity and larger breaking FET. Note it's larger size at 2.1 x 0.7 x 0.45 inches. All the software and functions are identical to the SW-COMPUTER.

• Normal Mode = SAFE - SEMI - FULL AUTO
• 3-Round Mode = SAFE - SEMI - 3-ROUND BURST
• Semi-Only Mode = SAFE - SEMI - SEMI

Specifications:

• Size = 2.1 x 0.7 x 0.45 inches
• Voltage = 8 to 16 VDC
• Peak Current = 250 Amps
• RMS Current = 30 Amps

Features:

1. Fully computer controlled MOSFET switching with Active Breaking.
2. Full electronic over current, voltage, and temperature monitoring, and protection.
3. Normal, 3-Round Burst, and Semi-Only operation.
4. Automatic 3-round burst to full auto operation after trigger is held for 1/2 second.
5. Full PWM motor speed control.
6. Soft Start to reduce motor and drive train wear.
7. Very low trigger switch current (~10mA).
8. Self diagnostics at power-up and during operation.
9. Mode, Burst Time, and Motor Speed are programmed via trigger pulls.
10. Low sound level motor vibration is used to signal the user.
11. Usually fits in present fuse holder space and replaces old fuse with high speed electronic monitoring.
12. All wires supplied and attached to the PC board (all are 24 inches).
13. Software can be upgraded by the user with a chip swap.
14. The design is fully open source to allow Third Party support

Specialty programming is available for things like Semi-Only locked operation and forced Semi-Delay for snipers.

More products are coming out from Extreme-Fire and what is in the works right now is the SW-Panther which is targeted to be more durable and might replace standard AB MOSFET switches soon.