This circuit is from a Hughes documentation from 1968. The components are of the time and the RC network determines the operating frequency of the circuit.
In fact, the original American publication exaggerated a little about the range that a good...
We found this circuit in an American documentation from the 90s. Through an LED it indicates the...
August 2017 - Mouser Electronics is announcing the availability of TDK ICS-52000 microphones with...