We found this circuit in the 1983 edition of the Electronics Experimenter handbook. The circuit uses components that are common today, although many admit equivalents.
This circuit was found in the December 1995 issue of Electronics Now magazine. The circuit...
In the figure we have the photo-conductive way of using a photocell to control a small motor with...
This circuit, which can be used on percussion instruments, has the oscillation point adjustment made in...