This indicator or logic probe was found in the April 1979 Radio Electronics magazine. The integrated circuit is the 555 and the FET can be any general-purpose type.
We found this circuit in a 1995 documentation. It is a two-channel preamplifier for supplying a...
In the figure we have the way to connect solar cells in series in order to increase their voltage. The...
This circuit is from the 1990 Motorola Data Databook. The circuit can be implemented with...