magic eye tube

Early models had a magic eye tube tuning indicator in front.

Magic eye tubes were used as the recording level indicator for tape recorders.

Magic eye tubes provided radio designers with a less expensive and more profittable way to add a feature usually found in higher price equipment.

Another product developed by the lab was a DuMont invention, the magic eye tube.

The album cover is a close-up shot of a Magic eye tube fitted onto vintage radio receivers from the 1930s.

A magic eye tube gives a visual indication for audio output, radio-frequency signal strength, or other functions.

The magic eye tube was also used on the cover of My Morning Jacket's 2011 album Circuital.

Magic eye tube - Small CRT display used as a tuning meter (obsolete)

At one time many radios used "magic eye tubes", a specialized sort of CRT used in place of a meter movement to indicate signal strength, or input level in a tape recorder.

A magic eye tube is essentially an inexpensive uncalibrated and not necessarily linear voltage indicator, and can be used wherever an indication of voltage is needed, saving the cost of a more accurate calibrated meter.

In 1932 DuMont invented the magic eye tube also known as the Electron Ray Tube, used as a tuning accessory in radios and as a level meter in mono and stereo home reel-to-reel tape recorders.