Found in a1967 Ferranti documentation, this circuit uses an operational amplifier from that time. The circuit uses a LDR as a sensor and has a null setting.
This circuit was found in a Popular Electronics of the 1990s. Its purpose is to expand the scale of...
This circuit can be used as an input shield by removing the signal directly from the second port,...
In figures 1 and 2 we have two current drains that can be made with operational amplifiers and...