Light dimming is based on adjusting the voltage that gets to the lamp to emit only small amount of light. Light dimming has been possible for many decades by using adjustable power resistors and adjustable transformers. Electronics controlling also made possible to make them easily controllable from remote location.
Most homes have lamps or fixtures that can be made brighter or dimmer by rotating or sliding a control on their on-off switch. Years ago, this was done using a device called a rheostat--a large variable resistor. This method wasted electricity and generated a lot of heat. To control the amount of energy going to the light the rheostat had to throw a lot away, turning it into heat. For example, at half brightness a 100-watt bulb would waste about 20 watts to heat in the rheostat.
Early light dimmer switches had a pretty straightforward solution to adjusting light levels -- a variable resistor. An ordinary resistor is a piece of material that doesn't conduct electrical current well -- it offers a lot of resistance to moving electrical charge. A variable resistor consists of a piece of resistive material, a stationary contact arm and a moving contact arm.
As charge works to move through the resistor, energy is lost in the form of heat. When you put a resistor in a series circuit, the resistor's energy consumption causes a voltage drop in the circuit, decreasing the energy available to other loads (the light bulb). Decreased voltage across the light bulb reduces its light output.
The problem with this solution is that you end up using a lot of energy to heat the resistor, which doesn't help you light up the room but still costs you. In addition to be being inefficient, these early dimmer switches tend to be cumbersome and potentially dangerous, since the variable resistor releases a substantial amount of heat.
Modern dimmers take a more efficient approach. Instead of diverting energy from the light bulb into a resistor, modern resistors rapidly shut the light circuit off and on to reduce the total amount of energy flowing through the circuit. The light bulb circuit is switched off many times every second.
Modern light dimmer switches use a transistor like device called a TRIAC to switch the electricity on and off very rapidly--120 times each second. Because they sort of 'chop up' the electrical power this way they are sometimes called 'chopper switches.' The current doesn't change suddenly. It rises and falls or, undulates.
The switching cycle is built around the fluctuation of household alternating current (AC). AC current has varying voltage polarity -- in an undulating sine wave, it fluctuates from a positive voltage to a negative voltage. To put it another way, the moving charge that makes up AC current is constantly changing direction. In the United States , it goes through one cycle (moving one way, then the other) 60 times a second. A modern light dimmer switch "cuts off" the sine wave. It automatically shuts the light bulb circuit off every time the current reverses direction -- that is, whenever there is zero voltage running through the circuit. This happens twice per cycle, or 120 times a second. It turns the light circuit back on when the voltage climbs back up to a certain level.
The knob or slider on the dimmer switch is also a variable resistor but, in this case it's just used as a signal to move the turn-on point --it's not redirecting the flow of current as the old time rheostat was. With the dimmer circuitry very little energy is wasted. A typical modern dimmer control is more than 99 percent efficient--less than 1 watt is wasted controlling a 100-Watt bulb.
If we hook up a really cheap dimmer switch, we may notice a strange buzzing noise. This comes from vibrations in the bulb filament caused by the chopped-up current coming from the triac (triode alternating current switch).
Better dimmer switches have extra components to squelch the buzzing effect. Typically, the dimmer circuit includes an inductor choke, a length of wire wrapped around an iron core, and an additional interference capacitor. Both devices can temporarily store electrical charge and release it later. This "extra current" works to smooth out the sharp voltage jumps caused by the triac-switching to reduce buzzing and radio interference.
Some high-end dimmer switches, such as the ones commonly used in stage lighting, are built around an autotransformer instead of a triac. The autotransformer dims the lights by stepping down the voltage flowing to the light circuit. A movable tap on the autotransformer adjusts the step-down action to dim the lights to different levels. Since it doesn't chop up the AC current, this method doesn't cause the same buzzing as a triac switch.
Most of light dimmer switches are built around the same simple idea -- chopping up AC current to reduce the total energy powering a light bulb.
Article Source: http://www.BharatBhasha.com
Article Url: http://www.bharatbhasha.com/home_improvement.php/71447
Article Added on Wednesday, March 5, 2008
| Other Articles related to "How Light Dimmer Switches Work" by Kimberly Quang | |
•Remote Control Lighting
The wireless age is here! Now is the perfect time to think about replacing those manual switches with a remote control lighting system. If the many benefits of remote control lighting are not immediately obvious, it can probably be attributed to the fact that this is still a very new technology. The uses and advantages of a remote control lighting system seem to expound indefinitely by those who use them on a daily basis. Once you try it, it will change your entire understanding of home...
•Bathroom Lighting Tips
If ever there were a room in your house that needs good lighting, it's the bathroom! Bathroom lighting must cover the gamut of every lighting situation you can imagine--from soft lighting in the morning as you wake up, to bright lighting for doing makeup and shaving. Bathroom lighting should come from many sources and directions and provide shadow free illumination as a task light. Who wants to put on makeup or shave with conflicting shadows on your face from poorly designed bathroom light...
•Bathroom Pendant Lights
Bathroom pendant lighting fixture offers a whimsical touch of elegance to your living headquarters. Homeowners, who install pendant lighting fixtures, tend to hang these in kitchens and over bar areas. These illumination fixtures are perfect for task lighting over kitchen counters, islands, tables, and other workspaces. These illumination fixtures are also becoming more popular within the bathroom area. There are now a variety of decorative pendant lights that will accommodate the design theme...
•Commercial Lighting Control System
Lutron's Grafik Eye is the premier lighting control system for virtually any commercial application. Lutron invented the world's first electronic dimmer in 1961, and has been innovating in lighting control technology ever since. Lutron's Grafik Eye has been used in restaurants, hotel lobbies and ballrooms, museums and even entire office buildings. Lutron's lighting control systems have been used in such exclusive locations as the Westin Hotel in Seattle, or London's Chelsea Harbor.
Benefits...
•MR11 Light Bulbs
MR11 bulbs can be used in your low voltage lighting design. These lamps have a multifaceted reflector, which is basically a pressed glass reflector. The interior parts of these bulbs are reflective and are made up of facets and a reflective coating. The facets provide a source of optical control since they have the ability to gather the light to form a single concentrated light beam. Some MR11 lamps have a smooth interior without the facets, but are still categorized as MR bulbs. Residents...
•Home Automation Systems
Having a system for home automation is extremely beneficial and rewarding. Not only do lighting controls make lighting rooms quicker and easier, but the home automation system adds security to your property and a warmth that a darkened home cannot offer thanks to the use of motion detectors.
Imagine retuning home on a cold night to find your abode brightly awash in light. Viewed from a shadowy driveway, especially on a chilly winter night, home lights can beckon you with a sense of a welcome...
•Light Bulbs Transformers Parts
Lighting parts and accessories is a diverse category of lighting related products designed to offer the homeowner or lighting professional new as well as replacement parts for indoor and outdoor lighting. Lighting accessories and parts for lighting fixtures may include the following categories of products:
Transformers
The heart and soul of a low voltage lighting job is the transformer. Every low voltage lighting project requires the use of a lighting accessory commonly called a power...
•Home Theater Lighting
Home theater lighting can transform your entertainment area into a vibrant work of art. Many homeowners are searching for new and exciting ways to entertain their guests, and superior lighting devices will usually do the trick. Modern day technology has given us innovative home theater products, such as big screen TV's, surround sound systems, and large scale entertainment centers to house such features. We all love to kick back with a bag of popcorn and watch a good movie from time to time....
•Light Bulb Evolution
After the invention of the incandescent bulb, newer, better ideas for light bulbs began to take off. In the early part of the twentieth century, experiments with various gases led to the advent of a wider range of light bulbs never before seen.
There are other types of light bulbs which arose from the notion of arc lamps. These involve sending electricity into a vacuum or gas-filled glass bulb or tube. If the glass is filled with neon gas, its electrons are excited, producing a light. The...
•Fluorescent Lighting Lamps
Initial cost and life long efficiency make fluorescent bulbs a good choice for general home and business lighting. You will be able to find a large selection of fluorescent light bulbs.
Cost effective fluorescent light bulbs are becoming the most popular type of bulb. Many environmentalists and energy misers are encouraging the replacement of incandescent bulbs with compact fluorescent lights. This is due to the fact that these bulbs use much less electricity and have a longer life span than...
| | Click here to see More Articles by Kimberly Quang
|
| Articles In LimeLight | Buying Discount Rims To Fit Your Budget
By Ernest Jarquio Added on Tuesday, April 22, 2008
Real Estate 101: What You Need To Know Before Closing
By Eric Bramlett Added on Sunday, April 20, 2008
The Basics Of Supply Chain Metrics
By Sam Miller Added on Tuesday, April 22, 2008
The Wonderful Effects Of Laser Hair Loss Treatment
By Bertil Hjert Added on Sunday, April 20, 2008
SUV - Four-Wheel-Drive Ultimate Style
By Roberto Sedycias Added on Tuesday, April 22, 2008
Help Keep Tabs On The Kids With Two Way Radios
By Gabriel Adams Added on Wednesday, April 23, 2008
Small Business And The Saturation Myth
By George Collins Added on Tuesday, April 22, 2008
Release The Butterflies - Planning Your Butterfly Themed Wedding
By Denise Sanger Added on Wednesday, April 23, 2008
Hair Loss Prevention Is Easy
By Bertil Hjert Added on Sunday, April 20, 2008
Spirituality - Inspirational Stories ( Part 69 )
By Vish Writer / Swami Vivekananda Added on Sunday, April 20, 2008
Used Car Loan Rates Affect Car Value
By Louis Rix Added on Sunday, April 20, 2008
Fitness Photography: The Other Half Of The Picture
By Tony Mandarich Added on Wednesday, April 23, 2008
Liquid Vitamin Supplement
By Mario Churchill Added on Wednesday, April 23, 2008
Detractors Claim Master Wealth Does Not Deliver
By D.H. Cannon Added on Tuesday, April 22, 2008
Finding Commercial Real Estate
By Kim Lee Added on Monday, April 21, 2008
DVD Players For Your Automobile
By Mark Robinson Added on Tuesday, April 22, 2008
Strategy Game
By Nikola Jankovic Added on Monday, April 21, 2008
Start Building Your Email Marketing List Today
By Uchenna Ani-Okoye Added on Wednesday, April 23, 2008
The Chloe Handbag - Makes A Great Gift
By Tori A Hewitt Added on Wednesday, April 23, 2008
Choosing A Day Care Center And Preschool For Your Child
By Andrew Ashworth Added on Saturday, April 19, 2008
|
|
|
