Jefftron Leviathan - EVO3 Airsoft Mosfet


Jefftron Leviathan - EVO3 Airsoft Mosfet





The JEFFTRON Leviathan - EVO3 is a processor-controlled MOSFET with Bluetooth communication.

This upgrade Leviathan for the ASG Scorpion Evo 3 is created by JeffTron. This fantastic device adds new shooting modes, controls your RoF, allows pre-cocking, active braking, low battery indication, statistics and so much more.

Everything is controlled via an application on your smartphone (supported by iOS and Android). The device is fully integrated inside the gearbox version ASG EVO 3 A1 and will replace the original electronics. As well as having so much to offer in terms of functions, this Leviathan device also keeps all the original functions offered by the Evo, ie. Empty magazine detection, bolt catch, burst fire, battery under-voltage protection, etc.

The Jefftron Leviathan Evo model comes with completely made wires to the front, with deans/T connector so no soldering is needed.

  • Adds new shooting modes independent for every position on the fire selector (SEMI - BURST - AUTO)
  • Three adjustable bursts (range 2 - 20 shots)
  • Rate of fire can be reduced to 40%. It adds breaks between shots to reduce RoF. It gives fast trigger response even with a very low rate of fire, just like in a real gun
  • In the package is included an ARL mode set to make anti-reverse latch which allows using pre-cocking, lower level active braking and DSG gears
  • Adjustable strength active braking (can be disabled with installed ARL mode)
  • Pre-cocking function for an instant shot on SEMI fire (can be used only with installed ARL mode)
  • Bolt catch lever has to be pulled after battery connection, which simulates load the bullet into the barrel like in the real gun
  • Empty magazine sound indication and bolt catch lever can be deactivated in the app
  • The delay between shots adds time in which isn't possible to shoot, it simulates the delay from gun reload or recoil (range 0,1 - 4,0 seconds)
  • Electronic fuse set is sensitive for high current detection to avoid any damage if something goes wrong
  • Low battery indication for 2S - 4S Li-Po and 3S - 4S Li-Fe
  • Statistics screen shows shooting output with cycle timing, motor current consumption, rate of fire and MOSFET temperature, which allows you to do fine-tune gearbox upgrade
  • Application shows actual battery voltage value. Colour lines indicate battery charge status
  • User can save multiple settings under profiles
  • Update function fixes bugs and adds new features to the device
  • There are three shot counters. Total count every shot during the device lifetime. User counter can be reset by the user anytime. Power-up counter is reset by battery connection
  • Error log shows errors made during the device life
  • For better security Bluetooth can be disabled by the selector switch (can be deactivated)
  • The motor vibrates and beeps as feedback for the user
  • Programmed settings are saved in the Leviathan - EVO 3 memory immediately after their change, so settings aren't lost when is Bluetooth or battery disconnected

  • Independent for every position on the fire selector (SEMI - BURST - AUTO)
  • SAFE: no responding on the trigger pull
  • Semi: your weapon fires a single shot per trigger pull
  • Semi/BurstX: short trigger pull fires a single shot, long trigger pull fires burst
  • Binary trigger: your weapon fires a single shot when the trigger is pulled and another single shot when the trigger is released
  • BurstX: your airsoft gun shoots a burst per trigger pull
  • BurstX+BurstY: short trigger press fires burstX, long trigger press makes burstX+burstY fire.
  • BurstX/Full: short trigger press fires burstX, long trigger press makes auto fire.
  • Full: gun shoots on auto until you release the trigger.

  • Easy installation inside the gearbox version ASG EVO 3 A1
  • No modifications are needed in the gun or Leviathan - EVO3
  • Compatible with Scorpion EVO 3 - A1, Scorpion EVO 3 - A1 B.E.T., Scorpion EVO 3 - A1 carbine with gearbox gen.1, version 2018 and version 2020
  • Compatible with stock and CNC trigger
  • Installation ARL Mode: with anti-reverse latch, you can use precocking, lower level active brake and DSG gears
  • It uses micro switch actuated by sector gear for perfect semi and burst fire timing
  • Thanks to advanced electronics, Leviathan - EVO 3 can be used with any common gearbox upgrade and gun rate of fire
  • Completely made wiring allows the fastest and the easiest installation into the gun, it is long enough for all kind of weapons with the battery placed in the front. No soldering is needed
  • There are high-quality wires 1.5 qmm (AWG16) with thin and hard MPPE insulation
  • Wire outer diameter is only 2.06 mm
  • The board is covered by conformal coating, which protects the Leviathan - EVO3 against water
  • Specified for common batteries up to 17V (Ni-xx 8.4 - 12V, LiPo 7.4 - 14.8V)
  • This device will increase your airsoft gun's rate of fire, and the battery holds longer than with basic wiring
  • With active braking ON the piston isn't partially stretched, the spring is fully released, the parts in mecha-box aren't under strain and the nozzle locks the hop-up chamber in greater part (depends on ROF)
  • In weapons with a very high rate of fire (ROF) active brake solves the issue of multiple shots firing whilst your weapon is in semi mode
  • The braking effect is the most powerful with a high torque motor
  • Remove from the gearbox: cut off lever and stock electronic - you will not need them with the Leviathan - EVO 3

Mobile application Leviathan by JeffTron to iOS and Android smartphone
Installation manual to Leviathan - EVO3 in English [PDF, 5.76 MB]
Leviathan by Jefftron Q&A discussion forum on Facebook


  • Leviathan - EVO3 drop-in electronic module with wiring to the front, Deans/T-connector
  • ARL Mode: Anti-reverse latch, spring and special screw
  • Two plastic washers under screw for securing device in the gearbox
  • Black Leviathan sticker 40 mm
  • Foam to keep the device in place
  • Installation manual in English


  • Installation of this device into the gearbox requires advanced technical skills!
  • Please read the information before installing your device to prevent any damage.
  • Short circuit or incorrectly connected battery will cause immediate damage to the device which is not covered by the warranty. It can lead to fire or even a battery explosion.
  • Disconnect battery, when you aren't using the gun! Otherwise, you will fully discharge the battery. Because the device drains a small amount of current from the battery all the time.
  • Don't connect battery when gun pointing towards you, another person or an animal.
  • Don't modify, repair and put into any kind of liquids or thermal shock the Leviathan - EVO3.


Remember - if you don't feel comfortable carrying out your own gun servicing, repairs or upgrades, we have experienced airsoft technicians in-store and can do the work for you. You can even book a service with us online by clicking the link below!

Book a Gun Service.


To buy an airsoft weapon in the UK you must have a valid airsoft defence.

This is not a licence, it is basically just proof that you intend to buy an airsoft weapon for use in airsoft.

An airsoft defence could be a UKARA or membership with the British Airsoft Club, and various other forms of defence.

You can only obtain an airsoft defence once you are over the age of 18.

To get an airsoft defence the law is that you should play at least 3 games of airsoft, and that you must have been playing for at least two months.
You can still buy an airsoft gun without a defence, provided you are 18 or older. If you choose to do this we would, by law, two tone (paint in a bright colour) parts of your chosen weapon. This is because an airsoft gun is considered a RIF aka Realistic Imitation Firearm, because they are so close to the real steel, whereas when you paint parts of it in a bright colour it becomes an IF aka Imitation Firearm. The reason being that the bright colours make it look less realistic to the public, and therefor less likely to be mistaken as real, were it to be used for any other purpose than airsoft.

When you order a gun from us you will need to add your defence details in the comments section of the cart. If you do not have a defence you will need to write the colour that you wish to be used for two toning your airsoft weapon.

Here is what's stated in the VCRA (Violent Crime Reduction) Act:

For airsoft skirmishing, the Association of British Airsoft is putting in place arrangements to allow retailers to check that individual purchasers are members of a genuine skirmishing club or site. The key elements of these arrangements are:
1. new players must play at least 3 (three) times in a period of not less than two months before being offered membership
2. membership cards with a photograph and recognised format will be issued for production to retailers
3. A central database will be set up for retailers to cross-check a purchaser’s details
4. member’s entry on the database will be deleted if unused for 12 months.
The defence for airsoft skirmishing can apply to individual players because their purchase of realistic imitation firearms for this purpose is considered part of the “holding” of a skirmishing event.
Size Chart