All About DIODES

This is the first of several tutorials about basic electronic. In this tutorial we will see symbols, uses and basics staff of DIODES. In the next tutorial known as  "Rectifier Circuits" we'll make and explain half-wave rectifier, full-wave rectifier and filtering of Voltage after that transitors etc. :) 
Stay tuned.


There are several types of DIODES. I'll look for the most used diodes. So let's see the Symbols.

GENERIC DIODE
As her title says it's generic diode which can be made from silicon (Si) or germanium (Ge). The breakdown voltage of Silicon diode is 0.7V and for Germanium is about 0.3V.




TUNNEL DIODE
Tunnel diode has breakdown voltage = 0V, in the forward direction has MAXIMUM (max) and MINIMUM (min) between these two acts as a negative-restistance element. What does it mean? That is when we increases voltage the Current will decreases. Because of that negative resistance it can be use for making high oscillations up to 20GHz also they can be used like faster switch.

PHOTO-DIODE
It's Germanium diode with dotted or surface PN junction. In the shut-off area presents resistance which value changes depends on intensity of light. This diode uses like faster light switch or indicator of brightness.

ZENER DIODE
In the breakdown area big changes of current doesn't occur almost no changes in voltage so it can uses for voltage stabilizer. Breakdown voltage is from 1.2V up to 150V. Zener diode connects vice versa in circuit, then Anode is on (-) and Chatode (+). 

LED (Light-Emitting Diode)
At least one time everyone see this diode it's well known LED (3mm, 5mm, 10mm) with all kind of color. What to say about it?  Well, everyone knows how it looks like and a lot of you who will read this, is at least one time checked it with Higher voltage than nominal and if you hit the right + and - the diode is DEAD :) hahah but I have little advice for you how to determine where is anode and cathode. First if you have the new LED the LONGER LEG IS ANODE (+) and the shorter one is CATHODE (-). Next, a lot of times we don't have the new one and then we have to desolder from some PCB. Then you can't see the longer LEG but you can see inside LED  and the smallest piece is ANODE (+)

VARICAP DIODE
Capacity of the PN junction changes with changes of voltage. They made of Silicon or Gallium arsenide. They uses on the High frequency up to 20GHz. Also they are used as Capacitor for tuning resonant circuits and for automatic frequency regulator in TV/Radio devices. 

  

That's it for these All About Diode #001 Tutorial :) 
Stay tuned :)