This circuit for receivers was found in an American documentation from the 90's. The circuit operates at up to 500 MHz. The integrated circuit used is uncommon nowadays.
Settings like this can be found in this section and on this website, but from different sources of...
This circuit was found in 1980s Electronic Engineering. Transistors can be modern equivalents. The...
This circuit oscillates at a frequency of 0.5 Hz. We can find it in an American documentation from the...