vu meter em84

Posted on Feb 7, 2014

From all the existing tubes, for sure the most interesting ones are the indicator tubes. From the 1930 ²s when they were invented, they captivated the eyes with the greenish shimmering light, thus the Magic Eye  term appeared. The magic eye tubes are just small CRT derivations, usually they also have a triode built-in, as an amplifier. I had two EM84 laying around for some time ( EM84 are cheap and easy to find,

vu meter em84
Click here to download the full size of the above Circuit.

mostly on eBay ), and as I was planning to start an all tube stereo amplifier, it made perfect sense to use magic eye tubes as vu-meters, although EM84 can hardly be called a magic eye, it is more a magic stripe . I am also experimenting with a preamp stage with a BC171 transistor ( a MOSFET would be a better choice for high input impedance ), but I think that in order to keep it all tube  I will try with a triode.

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