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gonug Offline

Posts: 5
Joined: Aug 2019
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Post: #1

All LED's stolpskyltar are semiconductor diodes. They create their light at the junction of their positive and negative sides. When power is applied to an LED, the electrons jump from one side to the other releasing light in the form of photons in the process. Different types of semiconductors produce different wavelengths and consequently produce different light colors. The warm white lights that we prefer in yachts is produced by Indium Gallium Nitride (InGaN). Add other materials, like phosphors and you get a pleasing incandescent light color.

Now, what happens when we apply voltage to this semiconductor is what we really need to look at. Apply the right voltage - in our application 12V - and the right amount of current will travel through the semiconductor and we get a beautiful, energy-efficient, bright light stolpskyltar that will glow for thousands of hours. But, we need the right voltage, precisely 12V.

You and I know for a fact that boats do not offer lab quality power! Start the engine, the generator set or connect to shore power and your environment has suddenly become hostile to your LEDs stolpskyltar.

Why is that? Simple! When the generator, alternator or inverter kicks in, we often see the voltage reaching upwards of 15V or higher. The higher the voltage, the more current goes through the semiconductor, the more electrons jump from one side to the other, the more light is generated and MORE HEAT is generated. And, guess what is the enemy number one of LEDs stolpskyltar? HEAT! We need to either control the heat produced or dissipate it. Apply a lot of current to an LED and you will get a very bright light for a very short period of time. Apply to little and you get a dim, useless light. That's what happened to you friends' LEDs.

In this application of semiconductor physics, we know that the current measured at junction of the materials is proportional to the voltage supplied. Controlling the voltage and consequently the current is paramount to the life expectancy of your LED.

Most inexpensive 12V LED stolpskyltar cluster bulbs being sold today use a ballast resistor which bleeds off energy to limit the current. This ballast resistor limits current according to a simple formula: Voltage/Resistance = Current. In that world, one can reach the right amount of current for an LED by using a ballast of the right resistance for the Voltage provided. Problem is, on a boat, the voltage is not always the same, it fluctuates. Consequently, the resistance being fixed, when the voltage drops, the current drops, and vice-versa. Conclusion: low voltage = dim light and high voltage = fried LED!

The result is the disappointment in LED lighting that you have heard about from all your cruising friends.

Most automotive and inexpensive LEDs stolpskyltar are based on the ballast resistor model. They work fine in automotive because the voltage variations are smaller than those found in the marine environment and also to the fact that most LEDs in the automotive world are used for turn signals or brake lights. These signals are not on for a long period of time so heat is not a problem. One can also use a resistor that will handle 14V while maintaining an acceptable current level for the LED generate enough light. This makes automotive LEDs stolpskyltar inexpensive, but unsuitable for the marine environment.

Now that we know that a ballast resistor is not suitable for our environment, what do we do next? Let's start with what we have learned so far. We know that a resistor is a passive device that can't maintain an even current with a changing voltage. So, what are our other options?
08-21-2019 04:18 AM
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