This IR light sensor circuit was found in the July 1992 issue of Radio Electronics magazine. It is tuned for 20 kHz modulated light.
We found this oscillator in a documentation for radio amateurs from the 1970s. The circuit can use...
Many oscilloscopes have high impedance inputs that make it difficult to observe high frequency signals...
This is the receiver for the previous circuit we found in the December 1992 Radio Electronics...