What Happened to Selsyns? The Devices That Transmitted Position Before Digital Encoders Took Over

Before digital encoders, computers, and modern position sensors, an ingenious electromechanical technology allowed machines to transmit precise rotational movement across long distances using nothing more than electrical signals. These remarkable devices were called Selsyns, later widely known as synchros. In this historical electronics documentary, we explore the fascinating rise and decline of Selsyn technology, from its origins in the late 1890s to its essential role in the Panama Canal, World War II naval fire-control systems, aircraft instrumentation, industrial automation, and early motion-picture equipment. Discover how Selsyn transmitters and receivers synchronized mechanical positions through electromagnetic induction, why engineers trusted these devices for decades, and how digital encoders and Gray code eventually transformed position measurement. We'll also examine the limitations that led to the decline of synchros, including mechanical wear, complex wiring, maintenance requirements, and difficulties integrating with digital computers. But the story doesn't end with their replacement. Synchros and their close relatives, resolvers, continue to serve in demanding aerospace, military, industrial, and electric vehicle applications where reliability remains critical. Why did digital encoders replace such an important technology? And why do engineers still rely on principles developed more than a century ago? Explore the forgotten engineering innovation that helped machines communicate position long before the digital revolution. Subscribe for more documentaries about forgotten electronics, vintage electrical engineering, and the technologies that shaped the modern world. #Selsyn #SynchroMotors #VintageElectronics #ElectronicsHistory #EngineeringHistory