In the figure we have a good rectangular signals generator with several frequency bands. The circuit is based on old logic but can be implemented with modern equivalents.
This second-order low-pass Salen-Key filter was obtained from an American 1980s documentation. Formulas...
This capacitive switch or approximation relay was found in a 1980s US publication. Power should...
This circuit is the equivalent of the CB121, but is triggered with the negative transition of the...