Found in the June 1987 issue of Radio Electronics magazine, this circuit uses well-known CMOS components. The circuit has a CMOS amplifier stage that drives a small speaker.
With the configuration shown in the figure, we have the relay being activated when the microphone picks...
We found this circuit in a 1992 Poptronics. What it does is to activate LEDs sequentially,...
In the figure we have an application of a voltage comparator in a circuit that fires with the...