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Designed for models that have pneumatic (air) retracts and servo-controlled gear doors, this circuit will allow you to sequence the action of the air valve and gear doors for proper timing and operation.  All the functions of this circuit can be adjusted to make it customizable for almost any model, including the direction (clockwise or counter-clockwise) of the rotation of the air valve, the delay between the cycle of the air valve and the movement of the gear doors, and whether or not the gear doors remain open after the gear are down, or close back up until the command to raise the gear is received.  In addition, the speed of the gear door servo is reduced for more scale-like movement, and to make the timing of the functions easier.  Plugs into a single channel in your receiver, and connects to both the air valve servo and the gear door servo(s).  Can be used for multiple gear door servos by using a common servo Y.  Check the Product Details section for a description of a typical installation.


Small, compact, and easy to set up, this is a great way to solve the problem of gear door sequencing without having to use multiple channels in your receiver and/or complicated programming of your transmitter.


NOTE: This circuit is for use in retract systems utilizing only one air valve, which is used to control the pneumatic retracts.  If you need a Sequencer that is designed for systems that use two air valves, one for the retracts and one for the gear doors, see the next item in this collection.


DOWNLOAD: Air Valve & Gear Door Sequencer

Air Valve & Gear Door (Servo) Sequencer

  • Weight:  12 grams

  • All of the "options" offered by this circuit are controlled from the main circuit board.  The red two-position Option Switches are used to select the option of closing the gear doors after the gear are down, and the direction of the air-valve servo's rotation.  Switch #1 reverses the rotation of the air-valve servo, which has the effect of reversing the "up" and "down" position of the gear.  This option is provided so that it is not necessary to reverse the gear channel's direction in the transmitter's programming, which would also reverse the "open" and "closed" position of the gear doors.  In the transmitter, select the position of the switch you would like to use for the gear doors' position, and then you can reverse the action of the air valve, if necessary, with Switch #1.  Switch #2 is used to determine whether or not the gear doors will remain open after the gear are down (P-47 style), or will close after the gear are down and re-open before the gear are raised (P-51 style).  The small blue trim pot located on the circuit board is used to adjust the delay between the time the gear begin to move and the gear doors begin to move, which allows for the different speeds that may be encountered on different air systems.  Since a microprocessor controls all of the unit's functions, the air valve will never be cycled until the gear doors have completed their movement, and until the delay for the movement of the gear has expired.


    Detailed instructions are provided.

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