Circuitron 5520 SD-2 Three Position Semaphore Driver

The SD-2 Semaphore Driver is designed for use with the CIRCUITRON TORTOISE and an upper or lower quadrant semaphore style signal. NOTE: Neither the TORTOISE, the signal nor the signal linkage are included. See CIRCUITRON?s Remote Signal Activator Kit on Page 35 . The SD-2 provides all the logic circuitry necessary to drive the signal to all three positions, and is designed to work with CIRCUITRON BD-1, BD-2 or BD-3 Block Occupancy Detectors. Other detection circuits that provide a logic low (- or ground) output may also be used. A minimum of 2 blocks must have detectors installed to allow 3 position indications. The SD-2 measures 2? x 3? and requires a 10-18 volt DC power source for proper operation.