This circuit was originally recommended to give the call signal on intercoms. However, it can be used with other applications. The circuit is from 1978 documentation. The transistor may be the BC548.
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...