#### soierr

##### Newbie level 2

Having this, I'm trying to calculate resistance R1 in order to obtain proper voltage drop on the diode.

First of all, I open datasheet for this particular diode and look at the plot below.

Let's say, I choose V

_{FM}= 0.3V which corresponds 600 mA. (Consider, T

_{j}= 25

^{o}C)

Now I can calculate resistor which is

R1 = (U

_{supp}- V

_{FM})/I

_{F}= (5 - 0.3)/0.6 = ~7.83 Ohm

So I have two questions:

Question1: Is this calculation correct ?

Question2: If this calculation correct then I have completely different probes as I simulate this schema

in proteus. See the picture below

Why is that ?