This RIAA equalizer preamp was found in a 1990s schematic. The transistors are an old version of the BC549 that can be used as a replacement. Signal input and output cable must be shielded.
This siren configuration using the 555 has already been explored in other circuits on this site. In...
This circuit generates a 1.46 kHz sine wave with an output ranging less than 1.5% in frequency...
This simple circuit for switching RF signals was found in an RF Design from the 90s. The circuit...