For a current of 5A and a supply of 6 V this circuit was found in documentation from the 70s. Transistors admit modern equivalents. Q1 is a PUT uncommon today.
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...