I am planning to using a buck / boost converter to run a DSLR camera from my USB powerbank AND other power sources. For that module I want to build with the buck / boost converter, I need a simple LED voltage indicator circuit, since I need to adjust the potentiometer from the converter whenever I change the source of power.
input: 5V from regular USB powerbank output: 8.4V to the camera coupler
input: 9V from DIY battery pack output: 12V to other application
What I want the circuit to do is, when I turn the potentiometer, I want a LED to light up when the output voltage is between 8.4V and 8.6V ( ready for camera ). And when it's in an other range, I want an other LED to light up.
I've heard something about a combination of resistors and z-diodes to do the trick ?
Additionally it would be perfect, if the indicator circuit is not depending on whether the output circuit is closed or not ( camera is pluged in or not ).
Pleas tell me your ideas and solutions.
I've found this link that shows this circuit
How does that work and how do I calculate the values for the parts ? I didn't understand the text on the linked page.