This configuration was found in the Texas Instruments optoelectronics manual. PNP transistors support equivalents and the phot transistor does.
The components of this circuit are not common today, as it was obtained in the Linear Applications...
Suggested by General Electric documentation from 1968, this circuit activates a relay after 60...
This basic amplifier circuit that can be powered by voltages from 6 to 24 V has the output...