This circuit was obtained in an Electronic Engineering of the 90s. The operational amplifiers and the sensor are from that time. The circuit has symmetrical power supply.
I found this circuit in an English magazine from July 1982. The circuit is still viable by using...
The circuit shown was found in the 1994 National Semiconductor's Linear Application Handbook. The...
This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose...