This circuit was featured in the March 1972 issue of Radio Electronics magazine. It adds automatic gain control to turntables by acting directly on the cartridge signal.
This Nixie pipe circuit was found in 1965 documentation. Note the high supply voltage. Appropriate...
This circuit is from a 1976 publication, but it can be assembled with modern components. For the...
Found in Popular Electronics from the 90's, this circuit consists of an audio oscillator for Morse...