This 1968 Mullard circuit detects fire by smoke using LDR-type sensors. The circuit makes use of transistors of the time that admit equivalents.
This low Power output stage can source a fraction of watt to a small loudspeaker. The transformer...
This circuit was obtained from an American 1980s documentation. The frequency depends on the...
This filter was found in Delco's 1965 documentation. It can be implemented with modern components...