Low noise amplifier (T466E)

Found in 1948 MIT documentation, this 4-tube amplifier is characterized by its low noise level.

Zero crossing detector (CB3887E)
This circuit appears in several configurations in this site. This is from American documentation from...
STK984 190E Integrated Power Module (COM160E)
November 2016 - Mouser Electronics is making available the new N Semiconductor STK984-190E power...
Heterodyne Mixer (CB4291E)
This is a typical 80's FM radio mixer circuit. The circuit was found in a documentation of the...