Using a 4046 PLL this circuit generates rectangular signals in three wavebands that depend on the capacitors used. The circuit is from a Radio Electronics from December 1989.
This circuit is from an 80's documentation, applying to ordinary comparators. The source does not...
This circuit produces an intermittent ring tone being triggered directly by the telephone line. However,...
This loop antenna was found in a 1990s documentation. The circuit includes a field strength meter. The...