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| [[Fichier:Diode-fiche-technique-1N4148-02.png]] | | [[Fichier:Diode-fiche-technique-1N4148-02.png]] |
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− | Ce graphique met en évidence une autre caractéristique importante des diodes – le courant maximal dans le sens passant ("''maximum forward current''" aussi noté If(max) ). | + | '''Ce graphique met en évidence une autre caractéristique importante''' des diodes – le courant maximal dans le sens passant ("''maximum forward current''" aussi noté If(max) ). |
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− | Just like any component, diodes can only dissipate so much power before they blow. All diodes should list maximum current, reverse voltage, and power dissipation. If a diode is subject to more voltage or current than it can handle, expect it to heat up (or worse; melt, smoke,…).
| + | Comme tous les autres composants, les diodes sont capable de dissiper une quantité d'énergie maximale avant de claquer. |
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− | Some diodes are well-suited to high currents – 1A or more – others like the 1N4148 small-signal diode shown above may only be suited for around 200mA.
| + | Toutes les diodes devraient lister les caractéristiques: |
| + | * maximum current - courant maximum, |
| + | * reverse voltage - tension inverse, |
| + | * power dissipation - puissance dissipée. |
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| + | Si une diode se voit appliquer une tension (ou un courant) plus important que ce qu'elle peut supporter alors attendez vous à la voir chauffer (ou pire; fondre, fumer, exploser, ...). |
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| + | Certaines diodes sont conçues pour des courants importants – 1A ou plus – d'autres diodes comme la 1N4148 est une diode "''small-signal''" et plutôt destinée à un courant d'environ 200mA. |
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| + | = Les types de Diodes = |
| + | == Les diodes normales == |
| + | Standard '''signal diodes''' are among the most basic, average, no-frills members of the diode family. They usually have a medium-high forward voltage drop and a low maximum current rating. A common example of a signal diode is the 1N4148. Very general purpose, it’s got a typical forward voltage drop of 0.72V and a 300mA maximum forward current rating. |
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| + | [[Fichier:Diode-1N4148.png]]<small><br />A small-signal diode, the 1N4148. Notice the black circle around the diode, that marks which of the terminals is the cathode.</small> |
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| + | A '''rectifier or power diode''' is a standard diode with a much higher maximum current rating. This higher current rating usually comes at the cost of a larger forward voltage. The 1N4001, for example, has a current rating of 1A and a forward voltage of 1.1V. |
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| + | [[Fichier:Diode-1N4001.png]]<small><br />A 1N4001 PTH diode. This time a gray band indicates which pin is the cathode.</small> |
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| + | And, of course, most diode types come in surface-mount varieties as well. You’ll notice that every diode has some way (no matter how tiny or hard to see) to indicate which of the two pins is the cathode. |
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| + | [[Fichier:Diode-CMS.jpg]] |
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| + | == Diodes émettant de la lumière == |
| + | The flashiest member of the diode family must be the light-emitting diode (LED). These diodes quite literally light up when a positive voltage is applied. |
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| + | [[Fichier:Diode-LED.jpg]] |
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| + | Like normal diodes, LEDs only allow current through one direction. They also have a forward voltage rating, which is the voltage required for them to light up. The VF rating of an LED is usually larger than that of a normal diode (1.2~3V), and it depends on the color the LED emits. For example, the rated forward voltage of a Super Bright Blue LED is around 3.3V, while that of the equal size Super Bright Red LED is only 2.2V. |
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| + | You’ll obviously most-often find LEDs in lighting applications. They’re blinky and fun! But more than that, their high-efficiency has lead to widespread use in street lights, displays, backlighting, and much more. Other LEDs emit a light that is not visible to the human eye, like infrared LEDs, which are the backbone of most remote controls. Another common use of LEDs is in optically isolating a dangerous high-voltage system from a lower-voltage circuit. Opto-isolators pair an infrared LED with a photosensor, which allows current to flow when it detects light from the LED. Below is an example circuit of an opto-isolator. Note how the schematic symbol for the diode varies from the normal diode. LED symbols add a couple arrows extending out from the symbol. |
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| + | [[Fichier:Diode-OPTO.jpg]] |
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| + | == Diodes Schottky == |
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