Found in an 90s Electronic Design, this circuit provides a 110 dB output to a ceramic transducer. The transducer is of the type available at the time.
This circuit uses a contactor having been found in a 1987 publication. More modern equivalent...
Only for reference this is a circuito f a commercial receiver of the year 1958. The circuit uses...
This astable multivibrator configuration causes two LEDs to alternately flash at a frequency...