The TRF receiver was patented in 1916 by Ernst Alexanderson. His concept was that each stage would amplify the desired signal while reducing the interfering ones.
In the preceding circuit diagram, each of those circular things is a vacuum tube, each about the size of a reddi-whip can and each needs the equivalent of 16 watts of power. Add to that the power supplies and amplifiers, the total comes to about 160 watts. The total size was about that of a dorm fridge.
Now with integrated circuits, the total draw of a TRF system comes to about .46 watts in a package that contains but one 14 (7 in-line) terminal IC, one four terminal IC power amp and six passive components. The total size was about that of a deck of cards. The circuit is not that much different from the old:
The first diagram illustrates the world when I was born and the second, the state of the art 40 years ago. I was 30 in 1971- do you believe there have been changes since then?
This is our Open Thread. How do you think technology has changed since you were born? Remember that the Apple II, the first genuine home computer, was introduced on April 16, 1977.