The E1T is a decadic counting tube developed by Philips, predating the invention of gas-filled Dekatrons. Each pulse advances the tube’s internal count by one and generates a voltage spike, which can be used to trigger specific actions. Internally, the E1T operates as a small cathode ray tube with a ribbon-shaped electron beam that occupies one of ten stable positions. The current position of the beam is indicated as a glowing strip, with each position marked with its corresponding value on a piece of film affixed to the tube’s glass envelope. The tube’s envelope is coated with a transparent protective layer, which is prone to cracking over time, particularly in damp environments. Consequently, E1Ts in pristine condition have become increasingly rare.