The end-viewed version had a round cone-shaped fluorescent screen together with the black cap that shielded the red light from the cathode/heater assembly. Later developments featured a smaller side-viewed noval B9A based all-glass type with either a fan type display or a band display (see the EM84). The earlier types were end-viewed (see the EM34), usually with an octal or side-contact base. The RCA 6E5 from 1935 was the first commercial tube. DuMont (who spent most of the 1930s improving the lifetime of cathode ray tubes, and ultimately formed the DuMont Television Network). The magic eye tube (or valve) for tuning radio receivers was invented in 1932 by Allen B. An earlier tuning aid which the magic eye replaced was the "tuneon" neon lamp.
Tuning indicator tubes were used in vacuum tube receivers from around 1936 to 1980, before vacuum tubes were replaced by transistors in radios. It was not until the 1960s that needle meters were made economically enough in Japan to displace indicator tubes. The magic eye tube was the first in a line of development of cathode ray type tuning indicators developed as a cheaper alternative to needle movement meters. Its first broad application was as a tuning indicator in radio receivers, to give an indication of the relative strength of the received radio signal, to show when a radio station was properly tuned in. The magic eye (also called a cat's eye, or tuning eye in North America) is a specific type of such a tube with a circular display similar to the EM34 illustrated. A magic eye tube or tuning indicator, in technical literature called an electron-ray indicator tube, is a vacuum tube which gives a visual indication of the amplitude of an electronic signal, such as an audio output, radio-frequency signal strength, or other functions.
0 kommentar(er)
