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A videophone can be defined as a telephone, which has a viewing screen and a built-in camera. The main advantage of a videophone is that you can talk and see with a person at the same time. It gives the impression that the person whom you’re talking to is right in front of you. Videophones can also be used to make normal voice-only calls. There are many other uses of the videophones. For example, videophones are also used for the video conferencing. Videophones are also desirable because of its increasing commercial purposes.

How To Use A Videophone

Using a videophone is a cinch. A videophone looks just like a normal phone with camera and built-in screen. The only difference between a videophone and an ordinary voice phone is that the videophone is equipped with an integrated services digital network (ISDN) or digital phone line. A wide variety of video equipments is available now in the market. Videophones are more expensive than the normal phones because of the high technology integrated into these phones. The average cost of a videophone is around $1,000.

Some telecommunications providers and cable companies offer ISDN services. Due to high availability of these services, anyone in the U.S. and the UK can install a videophone. Generally, an ISDN telephone line has two separate channels in order to provide high-quality pictures. Once you have an ISDN-equipped videophone, you can start making calls. The only problem in this system is expensive. Video calls cost almost double that of normal telephone calls. This service is also not available in some countries. According to the telecom companies, the call cost will be significantly cut in the near future.

Use Of Videophones By Deaf Persons

Videophones are the result of recent advancements in the telecommunication field. This is a very useful medium of communication for people who are hearing impaired. Sign language can be used with this phone because of the good picture quality provided by most service providers. To do so, you are advised to sign slower than you usually would in a face-to-face conversation. Also, lip reading is difficult because of picture quality and a possible time delay between sound and picture.

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The DC Power Supply is a rather fundamental electronic device, however there are hundreds of DC Power Supply products on the market from dozen of manufacturers. Narrowing down the best product for your application and budget can be a daunting task. This article addresses DC Power Supply differentiators, functions and the applications they are best suited for. The article’s focus is DC Power Supplies used by engineers, manufacturers, quality professionals and electronic hobbyists for the purposes of R&D, manufacturing and testing.

Power Supplies can range in price from $50 to $20,000 and the cost is often directly proportional to the amount of power the device outputs. The primary function of a power supply is to regulate output voltage and current. It takes an input power and regulates the output power as to enforce a constant voltage and current. In the case of DC Power Supplies, the input power is converted from alternating current (AC) to direct current (DC). There are two basic types of regulated DC Power Supplies: Linear and Switching.

Linear power supplies can never output a higher voltage than the input source. In theory, a linear power supply that is driven by typical 110V wall outlet could only output 110V, assuming the device were 100% efficient. Realistically, no power supply is 100% efficient because power conversion always results in energy loss, usually in the form of heat dissipation. Therefore, linear power supplies usually output voltage that is significantly less than the input.

Switching power supplies can step-up, step-down or invert the input voltage. Switching power supplies are usually larger, noisier and more expensive than their linear counterparts, however, switching power supplies are typically more efficient.

Choosing the right DC power supply for your application requires definition of some basic design specifications: voltage range, current range, number of outputs, power cleanliness (known as “ripple”) and programmability. In general, the higher the output voltage and the lower the ripple, the more expensive the DC Power Supply. Multiple outputs and programmability features will also add to the cost.

The least expensive DC Power Supplies are ideal for electronics hobbyists and basic electro-mechanical applications where only raw power is required. It is likely that the devices being powered in these applications already have power-conditioning features that eliminate the need for precision input power. Low power, single output, DC power supplies range in price from $50 to $200.

Mid-range power supplies are best suited for non-critical, laboratory projects involving more advanced electro-mechanical applications or basic board-level testing. Mid-range power supplies might have multiple outputs, higher power ratings, lower ripple and precision, digital metering (+/- .001V, +/- .01A). Mid-range DC power supplies can be linear or switching and could range in price from $200 to $1,000.

High-end applications requiring high output voltage, advanced programmability (GPIB PC Interfaces), numerous outputs and very low ripple should budget in excess of $1,000 for their DC power supply. Many laboratory, R&D and testing applications could easily spend $5,000 to $10,000 per power supply.

This article has introduced some basic features and applications of DC Power Supplies. Before making your final purchase, be sure to consult the manufacturer and thoroughly understand all the specifications of a particular product. Choosing the best and most economical DC Power Supply for your application does not have to be a complex and time-consuming task. By identifying your design parameters, you will quickly narrow down product selection to niche class of products from only a few manufacturers.

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