This circuit is from an American documentation from 1975. The circuit uses components of the time which can be replaced by modern equivalents. The coupler is homemade with a lamp and a photocell.
Found in a 1970 EEE, this circuit uses general-purpose transistors of the time. Transistors support...
This simple source using fixed voltage regulators can supply currents up to 1 A at the voltages...
Originally suggested by Harris in the 1990s, this circuit uses an optical tachometer. The circuit is...