We found this circuit in a magazine 73 for radio amateurs from the 80's. The circuit makes use of an epochal component which is programmed according to the table beside the diagram.
This well-known siren configuration using complementary transistors is from a 1980s documentation. The...
This circuit was found in an old American magazine and could make use of more modern components...
This circuit is from the Philips integrated circuits manual of 1990. It is intended for magnetic...