Below is a circuit where an LED will light on when the battery voltage (Vcc) is below approximately 8.8V. However, I'm confused as to how it works. My understanding is that when the battery voltage is less than 8.8V (6.8V Zener + 2.0V LED), the PNP will be in saturation mode, and thus the LED will turn on. However, when the battery voltage is greater than 8.8V, why does the LED turn off? Wouldn't the PNP be in active mode?
Please correct me if anything I've said is wrong. I apologise if this is a trivial question, but I've searched everywhere and asked a few older peers already. It also isn't very helpful when most resources on BJT transistors talk about NPN.