30-09-2013, 04:19 PM
INFRARED BUG
INFRARED BUG.docx (Size: 1.48 MB / Downloads: 39)
Introduction:
As next-generation electronic information systems evolve, it is critical that all people have access to the information available via these systems. Examples of developing and future information systems include interactive television, touchscreen-based information kiosks, and advanced Internet programs. Infrared technology, increasingly present in mainstream applications, holds great potential for enabling people with a variety of disabilities to access a growing list of information resources. Already commonly used in remote control of TVs, VCRs and CD players, infrared technology is also being used and developed for remote control of environmental control systems, personal computers, and talking signs.
For individuals with mobility impairments, the use of infrared or other wireless technology can facilitate the operation of information kiosks, environmental control systems, personal computers and associated peripheral devices. For individuals with visual impairments, infrared or other wireless communication technology can enable users to locate and access talking building directories, street signs, or other assistive navigation devices. For individuals using augmentative and alternative communication (AAC) devices, infrared or other wireless technology can provide an alternate, more portable, more independent means of accessing computers and other electronic information systems.
Wireless Communication
Wireless communication, as the term implies, allows information to be exchanged between two devices without the use of wire or cable. A wireless keyboard sends information to the computer without the use of a keyboard cable; a cellular telephone sends information to another telephone without the use of a telephone cable. Changing television channels, opening and closing a garage door, and transferring a file from one computer to another can all be accomplished using wireless technology. In all such cases, information is being transmitted and received using electromagnetic energy, also referred to as electromagnetic radiation. One of the most familiar sources of electromagnetic radiation is the sun; other common sources include TV and radio signals, light bulbs and microwaves. To provide background information in understanding wireless technology, the electromagnetic spectrum is first presented and some basic terminology defined.
The electromagnetic spectrum classifies electromagnetic energy according to frequency or wavelength (both described below). As shown in Figure 1, the electromagnetic spectrum ranges from energy waves having extremely low frequency (ELF) to energy waves having much higher frequency, such as x-rays.
555 TIMER:
The 555 timerIC was provides circuit designers and hobby tinkerers with a relatively cheap, stable, and user-friendly integrated circuit for both monostable and astableapplications. Since this device was first made commercially available, amyriad of novel and unique circuits have been developed and presented in several trade,professionaland hobby publications.
Operating modes:
555 Timer IC can be connected either in its Monostable mode thereby producing a precision timer of a fixed time duration, or in its Bistable mode to produce a flip-flop type switching action. But we can also connect the 555 timer IC in an Astable mode to produce a very stable 555 Oscillator circuit for generating highly accurate free running waveforms whose output frequency can be adjusted by means of an externally connected RC tank circuit consisting of just two resistors and a capacitor.
The 555 Oscillatoris another type of relaxation oscillator for generating stabilized square wave output waveforms of either a fixed frequency of up to 500kHz or of varying duty cycles from 50 to 100%. TheMonostable circuit produces a single output one-shot pulse when triggered on its pin 2 trigger input. In order to get the 555 Oscillator to operate as an astablemultivibrator, it is necessary to continuously re-trigger the 555 IC after each and every timing cycle. This is basically achieved by connecting the trigger input (pin 2) and the threshold input (pin 6) together, thereby allowing the device to act as an astable oscillator. Then the 555 Oscillator has no stable states as it continuously switches from one state to the other. Also the single timing resistor of the previous monostablemultivibrator circuit has been split into two separate resistors, R1 and R2 with their junction connected to the discharge input (pin 7) .
IC 78L05
The 78L05 is a self-contained fixed linear voltage regulatorintegrated circuits. The 78L05 fam is commonly used in electronic circuits requiring a regulated power supply due to their ease-of-use and low cost. the 7805 has a 5 volt output, The 78L05 line are positive voltage regulators: they produce a voltage that is positive relative to a common ground. 78L05 ICs have three terminals and are commonly found in the TO220 form factor, although smaller surface-mount and larger TO3 packages are available. These devices support an input voltage anywhere from a couple of volts over the intended output voltage, up to a maximum of 35 or 40 volts, and typically provide 1 or 1.5 amps of current (though smaller or larger packages may have a lower or higher current rating). 7805 is a 5V fixed three terminal positive voltage regulator IC .The IC has features such as safe operating area protection,thermal shut down, internal current limiting which makes the IC very rugged.Out out currents up to 1A can be drawn from the IC provided that there is a proper heat sink.