Electronics Basics - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 55

voltage, and the breakdown state does not destroy the component. Schottky
diodes have a low forward voltage drop. Tunnel diodes are extremely interest-
ing because they use quantum tunneling and are used for advanced circuits.
There are also many other common diodes, ones that could deserve their
own section. Laser diodes are special types of diodes that create laser lights;
you can i nd these components in consumer electronics like CD players and Blu-
ray recorders. Light-emitting diodes (LEDs) work in the same way, producing
visible and nonvisible light and are presented in the next section.
Using Diodes
Diodes are used primarily to protect circuits either by avoiding a reverse-voltage
or avoiding voltage spikes.
Electric motors can use large amounts of energy to make the motor spin.
When there is an interruption of current l ow inside the component motor, this
can lead to a sharp rise in voltage across the device circuit. If the voltage drawn
is beyond what the circuit is designed to handle, it may damage or destroy it.
Light-Emitting Diodes
Light-emitting diodes are exactly what their name implies; diodes, electronic
components that let current l ow in one direction only and that emit light. LEDs
are used as indicators in home electronics, and have started to replace tradi-
tional incandescent light bulbs in home and industrial lighting. They are far
more robust than light bulbs; they use less energy and exist in many different
colors, shapes, and sizes.
Most LEDs emit a single-color with typical colors being red, orange, green,
blue, and white. Dual-color LEDs also exist that can be either one of two colors
or a mix between two colors, and i nally, RGB LEDs exist that can take on almost
any color by varying the red, green, and blue components.
LEDs also exist that emit nonvisible light: ultra-violet and infrared. Laser
diodes are special types of light-emitting diodes, capable of creating laser light
in various wavelengths and powers.
Using LEDs
Using LEDs is remarkably similar to their parent family: diodes. However, the
difference is in their power consumption. Care must be taken not to supply too
much current to an LED; otherwise it is possible to damage or even destroy the
component.
LEDs have a larger voltage drop than their diode counterparts. Most common
red LEDs have a voltage drop between 1.8 V-2 V, yellow LEDs 2.0 V, green LEDs
2.2 V, and blue LEDs can have up to a 3.4 V voltage drop. Typical maximum cur-
rent for LEDs is around 20 mA for all LEDs, though blue versions can draw 30