This configuration can be found in several articles on this site. The one shown in the diagram is from the datasheet of the LM101 series amplifiers, but it can be implemented with other types.
This stage with polarization of only one resistor can use any general-purpose transistor. The...
This voltage-controlled potentiometer using an LDR was found in an English documentation. LDR is...
This interesting sensor for RF signals was found in an article in the June 1989 Radio Electronics...