Diodes

Diodes are semiconductors which allow electric current to flow in one direction and prevent it from flowing back.

All diodes have polarity, but unlike other components, the polarity marking is for the negative lead.

To prevent incorrect loading, put the marked side of a diode in the square pad or in the direction of the arrow symbol.
However, some PCBs may use a "+" sign. In this case, you must remember to put the marked side of the diode (negative lead) in the opposite pad.

PTH diodes are most commonly identified by:

   * one band and "1N" markings
   * one band on a glass-like body
   * small colored light (LED)
   * small colored light (LED)

Unlike resistors and capacitors, diodes are not identified by value, wattage or voltage.
They are given a JEDEC (Joint Electronic Device Engineering Council) identification number.
Each kind of diode (i.e. rectifier, tunnel, zener) has its own JEDEC number, but may have the same component shape or body.

The only way to positively identify them is by their JEDEC number.
Because all diodes are formed by one junction of dissimilar semiconductor types called "N" and "P", the prefix "1" or " 1NĄŻis used in the JEDEC system (for example, 1N4004, 1N914, 1N4733).

Diode Types