Alternatively referred to as a flash memory card, a Memory card is a type of storage media that is often used to store photos, videos, or other data in electronic devices. Devices that commonly use a memory card include digital cameras, digital camcorders, handheld computers, MP3 players, PDAs, cell phones, game consoles, and printers. The picture to the right is a MicroSD flash memory card, which is just one of the types of memory cards available.

Memory cards can vary in the amount of storage space based on the type of memory card. However, in general, most memory cards today range in size from as small as 4 gigabyte (GB) up to as large as 128 gigabyte. Older memory cards may be even smaller than 4 GB and you can find memory cards that are larger than 128 GB, but they will have higher costs.

The size of a memory card is fixed and cannot be increased. If your memory card is full, consider deleting some of the files stored on the memory card. Or, consider moving the files to a different storage device, or purchasing a memory card with more capacity and replace the memory card with the new card.

Speakers are one of the most common output devices used with computer systems. Some speakers are designed to work specifically with computers, while others can be hooked up to any type of sound system. Regardless of their design, the purpose of speakers is to produce audio output that can be heard by the listener.

Speakers are transducers that convert electromagnetic waves into sound waves. The speakers receive audio input from a device such as a computer or an audio receiver. This input may be either in analog or digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Since sound waves are produced in analog form, digital speakers must first convert the digital input to an analog signal, then generate the sound waves.

The sound produced by speakers is defined by frequency and amplitude. The frequency determines how high or low the pitch of the sound is. A speaker system's ability to accurately reproduce sound frequencies is a good indicator of how clear the audio will be. Many speakers include multiple speaker cones for different frequency ranges, which helps produce more accurate sounds for each range. Two-way speakers typically have a tweeter and a mid-range speaker, while three-way speakers have a tweeter, mid-range speaker, and subwoofer.

Wireless keyboards can be extremely useful computer peripherals, reducing cable clutter and allowing you to control a computer without having to be physically next to it. However, with many different types of wireless keyboard connection methods available, choosing the right one can be difficult. Knowing your wireless keyboard options can help you and your staff work comfortably and efficiently while keeping your office as cable-free as possible.

Bluetooth is one of the most popular methods of syncing a wireless keyboard with your computer. The technology is only effective over a short range, but it allows for reasonably high data transfer speeds and does not need a direct line-of-sight for connection. As such, it is ideal for use with office keyboards, as it creates a reliable connection that is not affected by on-desk clutter. Bluetooth keyboards are available in virtually all the styles that wired keyboards are, including ergonomically designed and Apple-specific versions.

Radio-frequency wireless keyboards are principally designed for long-range use. They use a broadcast method similar to the Wi-Fi standard used in wireless networking to communicate with a computer or other device. This method of wireless transmission gives them a greater range than Bluetooth keyboards, with some models able to work at distances up to 100 feet. However, RF keyboards are something of a specialized tool, and are generally more expensive than their Bluetooth equivalents.


This is a very simple explanation of the construction and function of LEDs. White LEDs need 3.6VDC and use approximately 30 milliamps of current, a power dissipation of 100 milliwatts. Therefore, a light-emitting diode (LED) is essentially a PN junction semiconductor diode that emits light when current is applied. By definition, it is a solid-state device that controls current without heated filaments and is therefore very reliable.


LEDs are highly monochromatic, emitting a pure color in a narrow frequency range. The color emitted from an LED is identified by peak wavelength (lpk) and measured in nanometers (nm ).

Peak wavelength is a function of the LED chip material. Although process variations are ±10 NM, the 565 to 600 NM wavelength spectral region is where the sensitivity level of the human eye is highest. Therefore, it is easier to perceive color variations in yellow and amber LEDs than other colors.

LEDs are made from gallium-based crystals that contain one or more additional materials such as phosphorous to produce a distinct color. Different LED chip technologies emit light in specific regions of the visible light spectrum and produce different intensity levels