This circuit was found in a 1968 documentation. It makes use of both NO and NC reed-switches and small magnets attached to a card in the form that results in the drive combination.
Found in a 90's EDN, this circuit generates signals in the frequency range given by the graph. The...
Found in Harris' 90s documentation, this circuit uses a zener as a stabilizer. The signals...
We found this circuit in a 90s Electronic Design. The circuit is based on a quadruple operational...