This Linear Technology circuit can measure currents from 100 pA to 100 uA. The circuit is from the 80's, using a component of the era. Transistors are general purpose types.
This receiver was obtained in a documentation from the 90's and is of the super-regenerative type....
This circuit couples 600-ohm signals to a line of the same impedance consisting of an amplifier stage....
The circuit presented is from an old magazine having been translated and published in a national...