We found this micro amplifier in a technical documentation from National Semiconductor. The circuit can be used on an experimental phone, being powered even by alternative power sources.
This low noise preamplifier has a gain of 19 dB in the 30 MHz band. The circuit is from the 80s....
The transformer of this experimental circuit, which appears in other versions on the website, is...
This circuit is from a 1968 documentation using one of the first integrated circuits available at the...