my mind needs refreshing so could someone please help explaining analysis of this circuit.
It is used for testing a current regulator (LED driver circuit) ('I' in the image). The regulator current is divided between a resistor and a series connection of a Zener, resistor and a LED. If D2 illuminates the current regulator is supposed to pass the test.
Majority of the current of course flows through the single resistor, but I don't understand the equation how it is exactly divided between the two circuit branches. I would like to replicate this circuit for testing a current source with different amperage, and thus would need the equation how to select proper values for Zener and the resistors.
Many thanks in advance.