I think one of your images is wrong - the parallel setup. In the parallel setup it should have an LED pointed in each direction. That would be "Two LED's". However, that same image (parallel but reversed diode) will also work. It will just not produce any light when the current runs opposite to the LED.two LED's or a single LED and a diode.
Actually they are both 100% correct. The purpose of the non-light emitting diode is to protect the light emitting diode from very large reverse bias.I think one of your images is wrong - the parallel setup. In the parallel setup it should have an LED pointed in each direction. That would be "Two LED's". However, that same image (parallel but reversed diode) will also work. It will just not produce any light when the current runs opposite to the LED.
by Jake Hertz
by Aaron Carman
by Jake Hertz
by Aaron Carman