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.
We found this circuit in a 1998 documentation. The circuit makes use of CMOS logic and must be...
Suggested by Siliconix in documentation from the 90s, this amplifier has its gain digitally...
Found in an old American publication, this is one of many possible configurations for an analog...