Opto control for triac (CB20552E)

Found a documentation for PC from 1992, this circuit is indicated for the English power grid of 240 V.

86 dB Gain Stage (CB6118E)
This circuit of the 70's uses transistors of the time. The circuit can amplify signals from 10 Hz...
Third-order separator filter (CB9618E)
This third-order Butterworth filter was found in American documentation from the 1980s. Formulas for...
Frequency Synthesizer 4046 (CB25257E)
We found this CMOS circuit based on the PLL4046 in the December 1989 issue of Radio Electronics magazine....