Electronic Zaerix Thermionic Valve (Vacuum Tube)

A valve (vacuum tube) is an electronic switch that controls the flow of electrical current. Valves are a basic electronic component used for circuitry and memory in First Generation computers. The valve pictured is a type 3B28 and was sold by Z and I Aero Services (also known as Zaerix), a UK company which specialised in re-branding and selling valves from around the world. The 3B28 valve type was first introduced around 1952.