Stereo FM Transmitter (CB8459E)

This circuit was found in a 90s Radio Electronics. The FM encoder or multiplexer is an uncommon component today.

Transistor Schmitt trigger (CB7801E)
Found in Popular Electronics, this configuration can be powered by voltages from 6 to 12 V....
Triac photoelectric control (CB8274E)
This circuit was found in a 1966 General Electric book. The triac and the day are from that time...
AC SCR photo control (CB8313E)
Found in Philips' 1967 documentation, this circuit makes use of period components. The SCR can be...