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by Kailash NR

Introduction

A diode is a semiconductor device with two terminals, typically allowing the flow of current in one direction only. There is a myriad of uses for diodes in modern electronics and its invention can be considered the beginning of the modern electronics revolution.

    • Be mindful of the battery terminals, they can heat up or momentarily spark if an electrical short occurs.

    • Do not light the LED without the diode in the circuit. New batteries may burn out the Red LED if connected directly.

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  1. A diode is a two-terminal electronic component that conducts current primarily in one direction. It can function as an electronic gate for controlling and directing the flow  of current. The circuit symbol for the diode is triangle with a line. The line denotes the negative lead of the diode and is found on the physical component as well.
    • A diode is a two-terminal electronic component that conducts current primarily in one direction. It can function as an electronic gate for controlling and directing the flow of current. The circuit symbol for the diode is triangle with a line. The line denotes the negative lead of the diode and is found on the physical component as well.

    • It has low resistance in one direction. (When the positive lead of the diode is connected to the positive terminal of the power source). In this mode of operation the diode is said to be forward biased.

    • But it has a high resistance in the other direction. When this is the case the diode is said to be reverse biased.

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    • Insert two batteries into the foam holder. Alternately, you can use the safety pin holder outlined in this guide

    • Note the positive terminal.

    • Take three wires of ~7 cm and remove 2 cm of the insulation from both ends of each wire.

    • After removing the insulation, twisting the bare wire strands together will make the ends more robust and easier to work with.

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    • Attach two of the wires to the terminals of the battery holder.

      • This can be done by inserting the wire and twisting it back on itself till it is tight. Make sure the bare wire is in contact with battery holder terminal and not the insulation.

    • Now attach the negative lead of an LED to the negative wire from the battery. The leads of an led can be distinguished by their length; the longer leg being positive.

    • Now attach the third strand of wire to the positive terminal of the LED.

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    • Its time to attach the diode to the loose wires . We will first do this with the positive of the diode connect to the positive on the supply. [Forward Bias}

    • At this point the LED should light up. This circuit diagram indicates the direction of current flow as well as the diodes direction relative to it. The diode is acting much as a conductor would act.

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    • Remove the diode from the wires and reverse its direction. The negative of the diode should be connected to the positive of the battery.

    • The LED will not light up. The diode is acting as an insulator in this case. Thus we can see that the direction or polarity of a diode determines its electrical characteristics.

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    • If the circuit refuses to light the LED in the forward direction, check the contact of the LED, wires and battery terminals.

    • Be careful not to short the terminals of the batteries. If the batteries heat up while in the holder, this could indicate an electrical short circuit. Remove the batteries and check your connections.

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    • A diode acts as a conductor in the forward direction, but how good a conductor is it ? in other words, is there some voltage lost across the the diode itself? Could you think of an experiment to find if this loss occurs?

    • Some of you would have noticed that the LED and diode are similar. Both are two pin devices that have a preferred polarity. This is because, L.E.D is short for light emitting diode and as the name suggests its a diode that also give off light.

    • In this guide we assumed, as per convention, that direct current flows form positive to negative for all the circuit diagrams. But one could easily imagine current as flowing from negative to positive, and the result would be the same. In fact electrons (being negatively charged) do move from negative towards the positive terminal.

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Finish Line

Kailash NR

Member since: 05/02/2017

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