Zener diode and special diodes (LED, photodiode)
Electronic Devices and Circuits · Engineering
Study notes
5V regulator: Zener (5.1V breakdown) in reverse across load; excess drops across resistor, Zener holds 5V. LED: 2V drop, 20mA via resistor from 5V. Photodiode in reverse: light increases current; used in remotes, oximeters.