How does an LED work?

LED means Light Emitting Diode. It is a 21st century solid-state semiconductor that was developed along with the transistors and integrated circuits now used in all our electronics. When a positive voltage is applied to an electroluminescent semiconductor junction, the junction emits a narrow spectrum of incoherent light. The color of the emitted light depends on the composition and condition of the semiconducting material used, and can be infrared, visible, or ultraviolet.

Among the visible-light LEDs are native red, orange, yellow, amber, green, blue, and pink, but we are most interested in "white" LEDs that can be used as a regular lighting source in our every day life. These are built using a blue LED covered by a "YAG" phosphor coating to re-emit yellow (down-converted) light with the blue to produce light that appears white to the human eye.

LEDs are very efficient in their conversion of electrical energy into light, and in a proper circuit with limiting resistor will achieve about 85% efficiency. They are also very long-lived, with expected lifetimes of 100,000 hours. However, they are also sensitive to overheating and overvoltage, so the lighting circuit is more complex than a simple plus and minus.

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How does an incandescent bulb work?

Over 130 years ago, Thomas Edison and Nikola Tesla worked on the development of devices to use electricity. One of the most important inventions was the incandescent light-bulb.

In an incandescent lamp an electrical current passes through a thin filament, heating it white hot until it produces visible light. It requires an enclosing glass bulb to prevent the oxygen in the air from reacting with the hot filament and quickly burning it up. The operating principle of an incandescent light is similar to that of blackbody radiation.

In most incandescent lights, approximately 85% of the electrical power is required to heat the filament, leaving only 15% to produce the visible light. This inefficiency has led some states to pass laws that ban the use of incandescent lighting within the next few years.

Incandescents work with either direct or alternating electrical current, and they are not polarity sensitive. Most of the filaments are made from tungsten and have a lifetime from 200 to 2,000 hours.

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How does a Halogen bulb work?

As the filament temperature of an incandescent bulb is increased, it will reach the point where the tungsten metal vaporizes and combines with a halogen (iodine or bromine) to form a gas within the bulb. As the gas decomposes, depositing the tungsten back on the filament, a halogen bulb emits a bright yellow light with a color temperature close to that of direct sunlight.

The efficiency of producing light is 10% to 20% higher for the halogen than for the incandescent bulbs, and the the bulb operates at a much higher temperature. The surface of the small bulb will reach 1,000 to 1,200 degrees F, enough to cause third degree burns and ignite paper and wood.

When you change out a halogen bulb, the package warns you to not touch the exterior of the bulb. The fear is that your fingers may leave a residue of oils on the surface, and when the bulb heats up, that residue can cause thermal cracking and destroy the bulb. So handle these bulbs with tissues or clean gloves. They will normally last up to 2,000 hours.

By the way, dimming a halogen bulb reduces its lifetime. It will operate at a lower temperature, and the tungsten will be redeposited on the glass rather than back on the filament. If you have a halogen bulb that is turning brown, that is what is happening.

CAUTION: Most of the halogen bulb fixtures in RVs are UL rated for 12-volt, 10-watt operation, though a few are rated for 20-watt operation.  A common mistake of RV owners is to replace the 10-watt bulbs with 20-watt bulbs. They look exactly alike and produce more light. But they also produce much more heat, and the 10-watt bulb is already hot enough to melt plastic and char the wood around the fixture.

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How does a fluorescent lamp work?

A fluorescent lamp or tube is a gas-discharge lamp that uses electricity to excite mercury vapor in argon or neon gas, resulting in a plasma that produces short-wave ultraviolet light. This light then causes a phospor coating the inside of the tube to fluoresce, producing visible light.

Present-day fluorescent tubes do not operate on regular AC or DC electricity -- they require that a "ballast" control the current flow and provide the startup and operating electrical power to the tubes. Since the 1990s most of the industry has converted to the electronic ballasts that convert the input power into a high frequency alternating current (up to 100 KHertz) that drives the tube.

By varying the choice of phosphor, fluorescent lights can be built with different color temperatures, ranging from a warm-white at 2,700K, cool-white at 4,100K, to daylight at 5,000K to 6,500K. They will have color rendering indices from 50% to 99%.

Fluorescent lighting is commonly used in RVs as a means for saving electricity. They are about 3 times more efficient than incandescents producing the same amount of light. This savings has fueled the drive to use AC-powered  compact fluorescent fixtures in stick-homes.

A downside of fluorescent lamps is that they contain mercury, and are thus considered to be hazardous waste when they fail. DO NOT put an old tube into the trash, but find a hazardous waste disposal site. Another downside is that the spectrum of fluorescent tubes contains a significant amount of ultraviolet light, known to be dangerous to a person's eyes and a partial cause of cataracts. Good lenses help filter out the UV, but they do not remove it all.

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How much more efficient are LEDs than other bulbs?

In the 12-volt systems of RVs and Boats, fixtures are designed to provide a specific amount of light (measured in lumens). What varies is the amount of electricity used to produce the useful light. The more heat that must be generated, the less efficient the fixture.

To a first approximation, here is where the electricity goes for various lighting:

		Heat	Light
Incandescent bulbs		85%	15%
Halogen bulbs		80%	20%
Fluorescents w/ballast		50%	50%
LEDs		15%	85%

Thus, LEDs can produce the same light lumenocity using about one sixth or better of the power of incandescents, about one third the power of fluorescents.

Incandescent bulbs use the other five-sixths of the power it draws to heat the tungsten filament which generates infrared radiation and heat. LEDs just do not generate all that heat. Definitely replace all incandescents with LEDs in an RV.

Halogen bulbs are touted to be more efficient than incandescents. They do this by vaporizing the tungsten instead of just heating it white hot. For a little more efficiency you get a much, much hotter bulb.

Fluorescents are a different calculation. Fluorescent bulbs are driven by a 48 volt alternating current generated by the "ballast" of the fixture. The bulbs are more efficient than incandescent, but there is inefficiency in the ballast, especially in a 12-volt DC environment.

LEDs use about 33% of the current of an equivalent fluorescent in an RV. 

Prudent RVer is now offering the fLEDescent replacement for fluorescent fixtures. It is necessary to gut the fluorescent fixture, removing both the tubes and the ballast, but what you get is a fully LED fixture providing the same amount of light as before, or if you choose, more or less light.

In a "stick-home" that uses 120 volt AC, some inefficiencies are introduced by having to convert the AC current into a DC current for the LEDs, so the savings there is less. LEDs take about 20% of the electrical power required by an equivalent AC bulb, or one-fifth. Replace all incandescents in a stick-home with LEDs or fluorescents (see below).

Savings is also a matter of investment expense. LEDs are more expensive than either incandescents and fluorescents, but they last up to 100 times longer than incandescents and 20 times longer than fluorescents. It makes good economic and earth sense.

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What kind of light-bulb do I have?

First, determine in what kind of electrical circuit the light-bulb is used. Is it 120-volt AC or 12-volt DC or 24-volt DC?

In a USA stick-house the standard electrical circuits for lights are 120-volt AC. You may find some fixtures (especially halogens) that have an AC/DC convertor that plugs into the house circuit and supplys 12-volt DC to specialty lighting.

In most RVs and boats, all the lighting is connected to a 12-volt DC circuit. That is so you have lighting even when not connected to shore (the pedestal). There are many owners who are surprised by this fact. Only in a rare few high-end rigs have I seen AC lighting; these are the exception.

Some older MCI bus conversions have house circuits of 24-volt DC, and since there are few 24-volt lights, this usually requires two 12-volt DC lamps be used in series in each light fixture.

Next, take the light-bulb out of its socket and look at it. You may be able to find the bulb number printed on the bulb base or on the glass. If you do, you can immediately check it out on the  Don's Bulb  website. This will give you more information than you normally need.

If the bulb comes from a screw-type socket (called edison sockets), it is probably a 120-volt AC bulb, though there is one exception I know of. The other most common kinds of sockets are the bayonet, wedge, and bi-pin. These are all used in DC circuits.

The base for a bayonet socket is solid metal with two little ears on opposite sides near the bottom. The following FAQs discuss different bulbs with the various bases and their LED replacements.

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Can my Bayonet Base light-bulb be replaced by an LED?

The Bayonet Base is a metal cylinder with small ears on the opposite sides that fit into slots in the socket and rotate into place like the bayonet on a rifle.

There are two diameters of Bayonet bases: 9mm and 15mm. LightBlasters only supports the 15mm base.

There are three types of 15mm bases: the BA15s, the BA15d, and the BAY15d.

The BA15s Single Contact Bayonet base has a single contact for +12-volt on the bottom of the base. The base shell is ground. Incandescent bulbs using this base include: 67, 93, 1003, 1073, 1139, 1141, 1143, 1156, 1295, 1383, and 1651. We support all these types, though space limitations where the bulb is used may limit what can be done with LEDs.

The BA15d Double Contact Bayonet base has two contacts on the bottom of the base: one for ground and the other for +12-volt, though no indication is given on which is which. The shell of the base is normally not connected. Incandescent bulbs using this base include: 68, 90, 94, 1004, 1076, and 1142. Since the LEDs have a required polarity, the base may need to be rotated 180 degrees to get the LED to operate correctly. LightBlasters offers replacements for these bulbs in certain applications and configurations.

The BAY15d Double Contact Index Bayonet base has two contacts on the bottom of the base, both +12-volt, one for one filament and the other for the second filament. Ground is provided by the shell of the base. These are dual function bulbs such as used for brake/turn signal lights, etc. Incandescent bulbs using this base include: 1016, 1034, 1154, 1157, and 1176. LightBlasters does not offer replacements for these bulbs.

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Can my wedge base light-bulb be replaced by an LED?

Wedge bulbs are made entirely from glass, including the base, with two wires wrapped around at the bottom to make contact with a socket measuring 2.1mm by 9.5mm. Incandescent bulbs of this type include: 194, 906, 912, 921, and 922. The 194 bulb is a miniature and sometimes used in applications where there is insufficient room to fit an LED. Otherwise, LightBlasters supports all these bulbs.

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Can my Bi-Pin Halogen light-bulb be replaced by an LED?

The 4mm Bi-Pin halogen (12v10w) using the G4 base in the puck fixture is replaceable. We do not have a solution at this time for vertically mounted halogen bulbs or the 6.35mm MR16 bulbs.

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Can my flourescent light fixture be replaced by an LED?

Yes, take a look at our new fLEDescent product. It requires removing the tubes and ripping out the ballast and uses the zipLED LightSticks on an aluminum plate to provide the light.

You can vary the number of LightSticks in the fixture to produce the level of lighting you wish to have. You can also include a dimmer in the package. Can you dim your current fluorescent light?

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What is a lumen?

If you put a collecter totally around a lighting device and count all the photons coming out from the device, that number corresponds to the total luminosity of the device. Any photon that is produced, goes into a dark reflector, and does not come out is not counted.

You can think of lumens like a quart of photons, but the engineers get much more exact than this, and there is an exact number of photons to make up one lumen.

The best way to measure the lighting capability of a LED is in terms of its luminosity in units of lumens.

A new incandescent 1156 bulb at a voltage of 12.8 volts, 2.1 amps, is specified to produce 402 lumens of light. Over its 1,200 hour lifetime, that will drop to around 280 lumens. This light is distributed omnidirectionally, so only a portion of it falls on the work you are doing -- at least half of it shines away from your work.

Three ZL3 zipLED LightSticks at a voltage of 12.8 volts, 0.21 amps, is specified to produce 135 lumens of light, all directed in a 150 degree cone in the direction the LEDs are pointing. That is why the zipLED solution seems brighter than the incandescent solution, and it surely is cooler.

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What is an amp-hour?

Quite literally, one amp-hour is one amp of electric current running for one hour. It is a surrogate measure for power used in discussing 12-volt systems commonly used in the RV and Boat environment where it is assumed the voltage is always 12 volts. One amp-hour at 12 volts produces 12 watt-hours of power.

A type-27 battery rated at 100 amp-hours contains about 50 amp-hours of useful power. You do not want to use more than half the stored energy from a battery, else you will damage the plates. 

In stick-houses on the grid, power usage is most commonly measured in kilowatt-hours. 50 amp-hours at 12 volts is equivalent to 0.6 kilowatt-hours. Therefore, a bank of four type-27 batteries has a capacity of 2.4 kilowatt-hours. That means your typical battery holds about $0.06 worth of electricity. But when you are off-grid, that much can make the difference between living well and sitting in the dark.                                                                                                                                                      

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What do you mean by off-grid?

The grid refers to the nation's electrical system, with all its power generation stations and transmission lines and transformers. It is what your house is connected to so it can receive the electrical power it needs to operate.

The grid is what you plug your RV or boat into when you connect the power cord to the pedastal. You are off-grid when you are not plugged in, depending upon your batteries or solar system or generator to keep going.

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What is the color temperature of LEDs?

Color temperature is determined by comparing its chromaticity with a theoretical, heated black-body radiator. Got that?

What people really want to know is how does the light from LEDs compared with their perceptions of light from other sources. Since the spectrum of light from a white LED does not have the same form as that of any other light source, the color temperature of LEDs is somewhat subjective.

LightBlasters original LEDs had a comparitive color temperature of 5,500K, a blue-white mixture we called cool-cool. We worked with the LED manufacturers to produce a warmer LED, and they provided a blue-yellow variety with a comparitive color temperature of about 3,500K, which we called warm-warm. We mixed these two LEDs into a cool variety (CWC = 2/3s cool-cool and 1/3 warm-warm) and a warm variety (WCW - 1/3 cool-cool and 2/3 warm-warm).

More recently, we have found an LED manufacturer that can reliably provide what we call a "natural" color, with a comparitive color temperature of about 4,100K. We are converting to this LED for all future products as inventories of earlier LEDs are exhausted. 

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Are LEDs a good replacement for fluorescent lighting?

LED lighting is an excellent replacement for fluorescent lighting, for several reasons.

There is a power savings of a factor of 3 when you use LEDs to produce the same amount of light as you were getting from the fluorescent.

Fluorescent tubes contain a small but accumulating amount of mercury, and it is considered a hazardous waste. You must dispose of if in the proper way.

Fluorescent lights produce a considerable amount of ultraviolet light that can damage the human eye and cause cataracts. This is of special concern for the older generation who have already had a bout with cataracts.

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Can I use LEDs in the tail lights of my rig?

LEDs are becoming more popular for lighting in automotive tail lights. However, LightBlasters nexLED kind of LED is NOT a good solution.

Most of the automotive lights require a high level of the red spectrum. The nexLED LED is very little power in the red or infrared part of the spectrum.

Go to NAPA or AutoZone or Flying-J for automotive LEDs.

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My bulb has two contacts on the bottom. What is it?

The B15 base comes in three varieties: BA15s and BA15d and BAY15d. The last two have two contacts on the bottom. LightBlasters supports only hte BA15d. See the question above.

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How can I use LEDs in my stick-house?

Since most houses are on the grid, their electrical system runs on 120 volts AC (alternating current). LEDs are DC (Direct Current) type devices.

We suggest you consider installing 120VAC to 12VDC convertors to provide a 12-volt power source that will work with the LightBlasters LEDs.

Kelly Walterscheid, designer of the nexLEDs and zipLEDs, is also working on the residential LED business. There is his ThinLUX spec sheet and a small ad for his products. I am getting prices so I can include these products as a reference sale here at Prudent RVer.

We suggest you consider installing 120VAC to 12VDC convertors to provide a 12-volt power source that will work with the LightBlasters LEDs.

In time you may want to convert your entire stick-house to 12 volts and use LEDs throughout. One way to do that is to move into an RV or a Boat. Brilliant.

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