This circuit was found in an integrated circuit manual from the 1980s. The circuit can be designed based on modern operational amplifiers.
In the figure we have the circuit of an amplifier for alternating signals with 10 times gain,...
This oscillator was found in the January 1996 issue of Electronics Now magazine. The frequency is given by...
This circuit is from a Popular Electronics from the 90s. It uses an opto-coupler with SCR directly...