The 6ME5 (also known as 6M-E5) is a miniature magic eye tube manufactured by TOYO in Japan. It closely resembles the common 6E5 tube, but in a smaller form factor, featuring the same basic display characteristic of a single shadow that opens or closes according to the applied input voltage. The tube operates at a relatively low target voltage of 180V, while a similar variant, the 6ME10, works at an even lower target voltage of just 100V.
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A magic eye tube, also known as a tuning indicator, is a type of vacuum tube that visually displays the amplitude of an electronic signal, such as an audio output or radio-frequency signal strength. These devices were frequently used in radio equipment to enable more precise station tuning.
The 6E5 is one of the earliest examples of a magic eye tube, invented in 1932 by American electrical engineer Alan DuMont. Designed as a cost-effective alternative to expensive needle indicators, it was intended for use in devices like radios that required user tuning without high precision. The first commercially available 6E5 tubes, sold by RCA starting in 1935, featured a coke-bottle-shaped glass envelope common in early vacuum tubes.
Unlike more modern magic eye tubes, the 6E5 has a relatively simple display characteristic, consisting of a single shadow that expands or contracts based on the supplied input voltage.