bc.gold 3,406 #1 Posted March 29, 2021 Magic eye tube 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 2 Share this post Link to post Share on other sites
formariz 12,045 #2 Posted March 29, 2021 Here is one in action on my McIntosh tuner. The bottom one. 2 Share this post Link to post Share on other sites
Skwerl58 763 #3 Posted March 29, 2021 Interesting stuff. I remember looking into the back of old TV's and radioes and seeing the vacuum tubes glowing. I have a Philco floor model radio from around 1935 that was my great aunts and it has rabbit ears attached to it. It is interesting because the dial is round and covers the earth in frequencies. It has a channel for airplanes that I would listen to when I was a kid. Lots of times it just roared. Great times!!! 1 Share this post Link to post Share on other sites
lynnmor 7,823 #4 Posted March 29, 2021 29 minutes ago, Skwerl58 said: Interesting stuff. I remember looking into the back of old TV's and radioes and seeing the vacuum tubes glowing. I have a Philco floor model radio from around 1935 that was my great aunts and it has rabbit ears attached to it. It is interesting because the dial is round and covers the earth in frequencies. It has a channel for airplanes that I would listen to when I was a kid. Lots of times it just roared. Great times!!! I still have my old Philco that was my great aunts, it is a 1937 that I had refurbished, it fits your description. It has a signal strength meter that is basically a lamp with shutters that move. Share this post Link to post Share on other sites