This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when light shines on a sensor.
The integrated circuit used in this 2002 project is not very common. It is powered directly by the...
We found this circuit in a documentation from the 50s. It is based on CK722 germanium transistors. The...
We find this current meter circuit from 0 nA to 200 nA in a Linear Technology application manual....