This interesting circuit was found on the Internet and is based on the 555. The circuit uses power MOSFETs that determine its output. No information about the transformer was provided.
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...