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.
The circuit, shown in the figure, activates a relay when the logic level applied to its input, from...
The traditional circuit was taken from a French magazine Radio Plans that no longer exists but can...
This circuit makes use of the LM11, 112 or 113 operatives and was found in a 1980s documentation. The...