This circuit was found in an American magazine 73 for radio amateurs of the 80s. It is an automatic transmission circuit for telegraphy. The circuit is TTL.
The circuit shown in the figure is suggested by Maxim (www.maxim-ic.com) and makes use of the...
The circuit shown in the figure below is suggested by ON Semiconductor (www.onsemi.com), based on...
Found in an American 1980s documentation, this circuit makes use of a sensor of the era uncommon...