Dual 3 Position Semaphore Servo Controller
This board is designed for Train Order Boards or paired Semaphores in ABS/APB Territory. There are two SG90 servos mounted facing each other so the board can be mounted below the bench work and operate either two blades on one mast or (depending on clearance) two masts on opposite sides of the track.
Each servo has adjustments for 3 positions (RED, YELLOW, GREEN) and local test buttons for each for easy set up and adjustment. The normal position is RED and inputs are provided for YELLOW and GREEN. Inputs are negative true.
The Sketch is a Jon Schmidt contribution and can be freely downloaded and modified subject to the Creative Commons license. The Eagle CAD board design is also open source so you can modify either to taste.
The Dual 3 Position Semaphore Servo Controller has a 2.1 mm power connector for 5 volts to power the Arduino Nano and the servos on board, it is NOT recommended that you power the board via the Nano's USB connector in a production environment. The Dual 3 Position Semaphore Servo Controller draws about 50 mA in the idle state and momentarily about 300 mA when the Servos are moving.
See (Dual Semaphore software developer Jon Schmidt's) article in the April 2023 RMC page 90 on this product!