This circuit was obtained in an Electronics Now from the 90s. The circuit uses operational amplifiers from the time and the indicator is of the Sonalert type with internal oscillator.
This circuit of a few watts of power shows a typical configuration from the 70s using driver and...
Scratch and Rumble are noises that appear when recovering vinyl recordings, both due to scratches on...
This circuit, already explored on this site, can be applied to other comparators in the same...