What’s a Diode? – Construct Digital Circuits

A diode is a part that lets present circulate in a single course and blocks it from flowing within the different course. It has two pins; anode and cathode.

The diode image seems to be like an arrow pointing towards a line. The road represents the cathode facet, and so does the road marking on the diode part itself.

Diode symbol and diode markings showing anode and cathode

How To Join A Diode in a Circuit?

A diode will block or let present circulate, relying on the way you join it in a circuit. Under you may see an instance circuit.

Diode connected in the correct direction so current can flow

Within the circuit above the diode is related in the best course. This implies present can circulate by it in order that the LED will gentle up.

However what occurs if we join it the opposite means round?

Diode connected in the wrong direction so current cannot flow

On this second circuit, the diode is related the flawed means. Which means no present will circulate within the circuit and the LED shall be turned OFF.

What Is a Diode Used For?

A regular diode is can be utilized for a variety of issues, from creating sound results to energy provides. Under you may see a couple of circuit examples with an evidence of what the diode is used for:

Sound Results Clipping: By putting two diodes in parallel in reverse instructions, you may get a clipping impact which creates an overdrive sound impact, usually utilized in guitar pedals.

Guitar pedal schematics where diodes are used to create the clipping/overdrive effect

Changing from AC to DC: Generally diodes are used to transform from AC to DC by putting 4 diodes to create a bridge rectifier. That is usually used after a transformer in an influence provide, adopted by a voltage regulator.

A basic power supply circuit

Defending from voltage spikes: Elements like motors and relays are principally inductors, which implies their present will attempt to carry on flowing after the facility is shut off. Diodes are used to securely discharge them.

Diode used to protect from voltage spikes

How a Diode Works

The diode is created from a PN junction. You get a PN junction by taking a negatively doped and positively doped semiconductor materials and placing it collectively.

The PN junction inside a diode

On the intersection of those two supplies, a depletion area seems. This depletion area acts as an insulator and refuses to let any present move.

Whenever you apply a constructive voltage from the constructive facet to the damaging facet, the depletion layer between the 2 supplies disappears and the present can circulate from the constructive to the damaging facet.

Whenever you apply a voltage within the different course, from the damaging to the constructive facet, the depletion area expands and resists any present flowing.

Issues To Notice About Diodes

  • It’s important to apply sufficient voltage within the “proper” course – from constructive to damaging – for the diode to begin conducting. Normally, this voltage is round 0.7 V to 1 V.
  • It has limits and can’t conduct limitless quantities of present.
  • Diodes will not be good elements. When you apply voltage within the flawed course, there shall be slightly little bit of present flowing. This present is known as leakage present.
  • When you apply a excessive sufficient voltage within the “flawed” course, the diode will break down and let present move on this course too.

Kinds of Diodes

There are a lot of totally different sorts of diodes. The commonest ones are:

Sign and rectifier diodes are just about the identical issues besides that rectifier diodes are constructed to deal with extra energy.

Zener diodes are diodes that make use of the breakdown voltage when making use of voltage the “flawed” means. They act as very secure voltage references.

Schottky Diodes have a decrease ahead voltage drop and quicker switching speeds than normal sign diodes.

Photodiodes are diodes which might be delicate to gentle. They let present circulate by them when uncovered to gentle.

Mild-Emitting Diodes (LED) are elements that gentle up when present flows by them.


Do you may have any questions on diodes or any suggestions you need to share? Let me know within the remark area under!

Extra Diodes Tutorials


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