This two-digit digital pressure gauge was found in the 1992 special edition of Radio Electronics Experimenter. A/D converter integrated circuits are uncommon today.
Found in a 1968 US publication, this circuit can operate on any power grid. The thickness of the wire...
In the figure we have a simple timer with the 555 feeding a relay directly. The circuit is from...
A simple electroscope can be made only with a 741, without the need for field effect transistors or other...