Phase and amplitude can be controlled in this circuit found in the May 1988 Radio Electronics magazine. The circuit requires a symmetrical power supply.
In the figure we have a typical detector stage for a radio receiver. The circuit is from 1963,...
Found in a 1968 Texas Instruments documentation this circuit uses an SCR from that time. Modern...
This circuit was obtained from an American publication of the 80's. The integrated circuit is of the...