The circuit shown was found in the February 1994 issue of Electronics Now magazine. The circuit records messages for a few seconds and plays them back as keys are selected.
This very simple circuit must use coal microphones of the type found in very old equipment. The...
This biestable circuit was found in a Popular Electronics from the 90s. The circuit has an unusual...
This circuit was found in a 1969 US documentation. It provides a signal that can be externally...