This series and parallel sensor circuit was found in Popular Electronics from the 1990s. Any SCR can be used and the supply voltage depends on the load.
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,...