This circuit for equipment adjustment and diagnostics was found in a Mullard transistors manual from 1960. Information about the transformers is given with the diagram.
This circuit is from a 2004 documentation serving for signals from 1 MHz to 160 MHz. The antenna is...
This filter of two transistors has the cutoff frequency determined by the formulas next to the...
This Philips commercial circuit is from the 90's documentation. The integrated circuit must be...