This two-tone alarm siren was found in the January 1975 issue of Radio Electronics magazine. The power transistor can be changed and with it, Rx has values from 10 to 47-ohm.
This circuit was found in an American documentation and can be added to common amplifiers of any...
This circuit reinforces signals in a frequency range between 1500 and 2000 Hz for use in...
This simple circuit indicates, through an LED, when the water level of a filter (or other kind of...