It's all well and good having a perfect, simple circuit but it it includes a switch, it will only work if the switch is in the on position meaning the circuit is closed. You can learn more about ...

When drawing circuit diagrams, rather than drawing detailed components, we use simple symbols to represent the different components.

I was convinced that there must be a way that a programmable zener diode, such as the TL431, could be used but I found no simple circuits ... a small initial current draw by the TL431.