This is the version of the previous circuit for vehicles with positive ground. The circuit is from a Radio Electronics from December 1976. A siren is included.
This timebase was found in a European 1980s documentation. The circuit uses well-known components...
This amplifier stage with 1 power transistor was found in the Radio Electronics magazine of...
The basic idea of this 1989 circuit is to trigger a relay for a while when a call signal occurs on...