I have searched in over voltage protection (like MOSFET.) I wanted to use a Zener diode in parallel so it won't dissipate power unless in over voltage protection, but its power is low so I read that I need a resistor to control the current passing through it.
I found people put the resistor in this shape:
This resistor will dissipate power, so I thought if we can put resistor like this:
In this situation the resistor (R3) will only dissipate in case of over-voltage but in desired voltage current won't pass through zener so won't pass through the resistor.
- Is the voltage going to the LED equal to source or to the Zener?
- Is the new placement for the resistor right? If wrong, why?
- Is there another placement for resistor if this doesn't work ?**