This circuit divides the grid 60 Hz frequency to obtain 20 Hz to drive mechanical watches used at the time. The circuit is from a 1970 CQ magazine.
This circuit is from the 1994 Linear Applications Handbook. The operational circuit can be...
This circuit is suggested by National Semiconductor (now Texas) in an old manual. The circuit...
With this circuit, found in a 80s Popular Electronics, it is possible to use two ordinary phones in a...