Diode Tutorial for beginners- Electronics Crash Course #11
Channel: Saral Tayal
Date: 2019-02-24

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Video Article-

In a nutshell diodes are used to control the direction of the current flow. Diodes are made from semiconductors, the same materials that make transistors and that power the device you're watching this video on!

Different types of diodes exist from zener diodes to even light emmiting diodes LEDs, schottky diodes, and recitifier6diodes. We'll talk about the most basic form of diodes, the general purpose signal diode in this video

Think of diodes as a one way lane of electronics

When we apply a positive voltage along the Diode, it acts like a conductor of electricity. The techinical term for this is forward biased

However when a negative voltage is applied to it, the Diode acts like an open circuit that cannot conduct electricity.  This is called a reverse biased state.

Diodes are represented in circuits using this symbol and as you can see, they only have 2 terminals making it extremely easy to wire. This flat triangle side here is the anode and the pointy triangle side is the cathode. 

Most diodes have an ofset white line. This represents the______. Current flows in the direction of the triangle. Do note that this is for the conventional current flow and not so the actual elecgron flow.



Let's run through a couple of quick examples to understand how they work


Insert simple circuit video + quick p&N junction explainations


Now diodes aren't perfect. In the real world, they incur power loss when conducting electricity and do incur some voltage leak when a negative voltage is applied. We use the current voltage relationship graph to understand this behaviour. 

Looking closer at the graph we see that there's this breakdown period. Here we see that when too much of a negative voltage is applied, the Diode will incur a breakdown where it becomes a conductor.

The graph also shows us that the Diode has something called a forward voltage. This is the bare minimum of positive voltage required for the Diode to "turn on" and become a conductor.this depends on the semi conductor used and is typically 0.6-1v for silicon based diodes and a lower 0.3v for germanium based ones.


Use cases 
Rectifier- diodes can be wired to convert ac voltages found in households into dc voltages most electronics devices use. A single diodes can make a half wave rectifier that cuts all the negative parts of the a.c. wave. 4 diodes can make a full bridge rectifier.

Reverse current protection. They protect against reverse current. This can be anything from plugging in your batteries in the wrong direction to even protecting from reverse current from a electric motor slowing down aka fly back diode. 

Logic gates. Depending on the way we wire diodes,  we can make AND , OR logic gates