This circuit is from an old Japanese publication of 1962. The circuit uses two batteries, one for the filaments of the tubes and the other one of high voltage for the plate circuits.
This interface was found in a Modern Electronics magazine from 1990. Although the circuit is...
This circuit, found in a 1980 publication, limits the amplitude of the output signal to a value...
The circuit is from old documentation from the 70s, but the components are still common, as the...