Found in Popular Electronics from the 90s, this circuit detects modulated infrared radiation and serves as a test for remote controls. Infrared sensors equivalent to the one indicated can be used.
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...