The easiest way to the functioning of a diode to explain, is a visible and known live from the replacement model.



In this case, always a model of a non-return valve used. Just here:



GRAPHICS



The graph shows such a check valve. In the water condition pen pushes the ball down and the valve is closed. The diode behaves analogously to do so.


Now you can pass water in the direction of flow into the valve, must first reach a certain pressure to ensure the spring force to be overcome and thus the ball upwards to press. According to this force must be in the flow of diode voltage overcome.


Once this threshold has been overcome, the ball is pushed upwards and the water flowing through it, just the electricity in our tiny diode.



It turns the whole thing now and leave water from the other direction to the influx of valve, there is no possibility of the water, the valve to open, on the contrary, the ball is on the rise in pressure is always solid against the tapered horizontal pipe down.
The diode behaves well here largely analogue, at least to a certain tension.



Here comes the only exception. Will lock in the direction of a certain voltage is exceeded, the so-called breakthrough voltage, the diode forward in this direction.


This would correspond to a breakup of the ball in the check valve date.