Recording Amplifier (T1278E)

This is a typical circuit used in a tape recorder in 1948. The circuit has 4 tubes, including the rectifier and headphone monitoring facilities.

Voltage Controlled Unijunction Oscillator (CB4432E)
In the figure we have the way of modulating or controlling the frequency of a relaxation...
72W Amplifier with the MC1536 (CB4495E)
This circuit, found on Motorola's Linear Interface ICs uses the MC1536 as a driver for a 36 W or...
Digital Switch Mixer (CB4919E)
This circuit was obtained from an ancient American documentation, but appears elsewhere in this...