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 old documentation, this circuit uses components that are still common on the market. The...
This circuit is from the American magazine that no longer exists Science & Electronics,...
This circuit was found in a 1969 US documentation. It provides a signal that can be externally...