Low noise amplifier (T466E)

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

Bidirectional Current Sensing NCS21xR (CB19648E)
This circuit was obtained directly in the component's datasheet, and in it we have the use of...
Audio Selector (CB213E)
S1 changes the selection of the input signals in the circuit shown here. Other type of circuits,...
Tone Control (CB19236E)
This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it...