Diodes

How are Diodes formed?

When P Type and N Type materials join together

What is a Diode?

An electrical one way valve that results from interactions at the junction of the N Type and P Type material

Current can pass easily in one direction but:

It is blocked in the opposite direction

Why is the orientation of the battery in a circuit important?

Because current can only flow in one direction

What is it called if current is able to flow?

A Forward Biased

What must happen in order for the circuit to be forward biased?

The P type material should be connected to the battery’s positive terminal and the N type should be connected to the battery’s negative terminal

What is a P type material also known as?

The Anode

What is an N type material also known as?

The Cathode

What does the excess of electrons at the battery’s negative terminal do?

Repel the free electrons in the N type material and sends them towards the junction

The electrons in the N type material then cross over the junction to:

Fill the “holes” in the p type material, and current flows through the diode

What does reversing the diode’s connection to the battery do?

It creates a new set of conditons

Why do the N type material’s free electrons move away from the junction?

They are attracted to the opposite charge on the battery’s positive terminal

Since the electrons have moved away from the junction:

No electron transfer takes place there and current flow stops

What does a reverse bias refer to?

A situation in electronics where a voltage is applied across a diode in the opposite direction of its normal current flow, effectively blocking most current from passing through it

What is the most common application for diodes?

Rectification

What is Rectification?

The conversion of AC into DC

Since a code only permits current flow in one direction:

It will only pass either the upper or lower half of the waves

When current only passes either the upper or lower half of the waves, what is it called?

Half Wave Rectification

Four Diodes can be connected in a diamond configuration to:

Create a full wave rectifier, which is the foundation for most DC power supplies

What are Diodes also used for?

Rectification in automotive alternators

What happens in Automotive Alternators?

Generated AC is converted into DC to be used in the vehicle’s electrical system

A diode only outputs:

DC current

What will happen to any AC current that passes through a diode:

It will be converted to DC

Only the positive or negative values of the AC signal:

Will be output