We found this receiver circuit for modulated light in a 90s Popular Electronics. Equivalent audio amplifiers can be used. Transistors are commonly used.
The circuit shown in figure 5 generates square signals based on a transconductance operational amplifier...
By adding a transistor to the output and some polarization features we can obtain a higher output...
Found in the 1990 special issue of Radio Electronics Experimenter magazine, this circuit uses an...