This 1967 Philips circuit recognizes a light signal (visible or infrared) modulated by tone. The circuit makes use of components of the time that are equivalent to the current BCs.
This circuit is suggested by National Semiconductor and has an excellent gain, for a photodiode as a...
With the circuit shown, when the brightness of one lamp decreases, that of the other increases. There is...
We found this circuit in an Intersil documentation. Temperature sensors are special components of the time,...