This adjustable circuit from 0 to 200 nA was found in a 90's EDN. The components can still be found relatively easily, as they are CMOS.
The configuration of this circuit was suggested by an old English publication that comes to...
Using comparators, this circuit can be used in a measurement bridge. The balance indication is...
Found in a 1999 documentation, this circuit makes use of a power germanium transistor and a...