ZENER Diode |
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The diode zener occupy a space of great relief in the world of the semiconductors. Mainly because with they the greater part of the stabilizing circuits is come true, secondarily because they are simple and economic components much, equips you of two electrodes, the cathode and the anode, like every other model of diode .Externally, the diode zener can assume various shapes and expressions, but its inner composition reflects always the same structural concept: that characteristic one of a semiconductor diode , constructed with very specifies geometry and opportune d oping, in order to sustain, without to endure damages, a determined value of inverse voltage applied to its finishes them. That is a voltage that polarizes the diode in contrary sense, with the anode on the line of negative feeding and the cathode on that positive one. But about that it is spoken little more ahead. For hour, instead, it convene to remembers, through two elementary circuits applied to you, one characteristic common electrical worker to the normal diode , when these are polarize to you directly.We make therefore reference the outline of figure 1, that it is fed with the d.c. voltage of 9 V and in which potentiometer the R1, of type to linear variation, can catch up 470 the maximum value of ohm, while the R2 resistance 100 conserve that fixed one of ohm.
Fig. 1 - This simple circuital experiences demonstrates them that, also varying the resistance in series inserted from potentiometer R1, the voltage on finishes them of the diode to the silicon remains the same one almost, around to the value of threshold of 0,7 V.
Components: R1 = 470 ohm; R2 = 100 ohm; D1 = 1N4004.
The tester is set in the measure of the d.c. voltages and on the range of 2,5 deep-scale of V. the silicon diode D1 is represented from common 1N 4004, that it goes applied in directed polarization, with ring indicating of the position of the cathode turned towards the clip the negative of the battery. Once composed the circuit of figure 1, second how much illustrating in the constructive project of figure 2, the experiment can begin, reducing itself to the single observation of the index of the tester during the free spins of the hinge of potentiometer R1, in ahead and to behind.
Fig.
2 - Practical
realization
of the experiment with which the function of
stabilizer of voltage
carried out from a diode is demonstrated. The tester is set in the scale of the measures of the
d.c. voltages and on the 2,5V range. The
result is following: the index of the tester marks it the value of voltage
of 0,7 V and remains almost immovable also when it is made to
vary the resistance, in series to the circuit, inserted from the potentiometer. With this test, therefore, it has been demonstrated that
the D1 diode leads current, but the fall of voltage on its
terminals is limited them to the value of threshold of the diode, that it is exactly that one of 0,7 V. |
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