Triac Heating control (CB21372E)

We found this circuit in a 1966 RCA manual. The integrated circuit is unusual, and the Triac must match the load.

27 MHz receiver (CB19446E)
This receiver was obtained in a documentation from the 90's and is of the super-regenerative type....
Line Driver (CB24229E)
This circuit couples 600-ohm signals to a line of the same impedance consisting of an amplifier stage....
Tachometer with Direction of Rotation Indicator (CB11572E)
The circuit presented is from an old magazine having been translated and published in a national...