This circuit was found in a Hands On Electronics from the 80's. The circuit emits an audible alert when dawn and the sensor receives solar illumination.
This is the circuit of a sensitive voltmeter using a difficult-to-obtain 5 uA full-scale...
The circuit is from the United States Hands-On Electronics magazine, February 1987 edition. The...
The circuit shown was suggested by Analog Devices (www.analog.com) in its Application Note AN-411...