Motor Starter Basics

Hidden inside this tiny mid‑1950s circuit board are two of the rarest early solid‑state devices you’ll ever see: a pair of Marvelco J‑3 germanium transistors, each stamped with that distinctive red‑oval “J‑3” marking. Marvelco was a short‑lived, almost forgotten manufacturer operating during the earliest days of the transistor revolution. Their devices were hand‑assembled alloy‑junction germanium PNP transistors, built in small batches and used in experimental gear, intercoms, and early transist