Found in a 90s Electronic Design, this circuit is used with a 9 V adapter for powering small circuits. The maximum current is given by the 250-mW regulator.
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...