12+-+Diodes

**Diodes**


 * Example: **


 * Circuit symbol: **

**__Function__** Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow.

__**Forward Voltage Drop**__ Electricity uses up a little energy pushing its way through the diode, rather like a person pushing through a door with a spring. This means that there is a small voltage across a conducting diode, it is called the forward voltage drop and is about 0.7V for all normal diodes which are made from silicon. The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current-voltage graph).



**__Reverse Voltage__** When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few µA or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction.