This setting applies to virtually any photo transistor and any operational amplifier. The power supply must be symmetrical, and the gain is determined by the relationship between R2 and R1.
In the figure we have the circuit of a simple humidity sensor with the 4011. The circuit was found...
We found this receiver for the 144 MHz band in a European publication from the 1970s. The circuit...
We found this circuit in an ancient American documentation. It can be adapted to operate in other...