The integrated circuit used in this 1975 application no longer exists, and it is also not indicated in the original diagram and must be of the TAA series by the diagram.
Of course, the range of this transmitter found in a 1992 documentation is not exactly 4 km, as it...
This sensitive circuit was found in the June 1995 Electronics Now magazine. R1 can be from 10k to 1M...
This logarithmic gain operating configuration was found in the June 1994 Electronics Now magazine. The...