AC Switch with Triac (CB25855E)

The load controlled by this circuit depends on the triac used. The circuit is from Electronics Now magazine from June 1995.

SCS 5 kHz stages (CB9068E)
This SCS counter circuit was found in a 1964 General Electric documentation. The circuit has a...
Reflex receiver (CB23633E)
This simple 1-transistor reflex receiver was published in Radio Electronics magazine in September 1959....
High Impedance Differential Amplifier (CB4896E)
Operational amplifiers used in this 80's circuit is not very common today, but the setting can be...