This circuit generates signals in four frequency bands with the threshold values indicated in the diagram. The circuit was found in the March 1996 issue of Electronics Now magazine.
Found in a 1968 Ferranti documentation, this circuit can be implemented with modern equivalent...
The purpose of this circuit found in an old Elektor is to light a lower power lamp when the bigger...
This circuit is from an old American amateur radio manual. The circuit shows how to use a Varicap...