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Why is knee voltage is different for different colour LED'S?
The knee voltage, or forward voltage drop, varies for different colored LEDs due to the materials used in their construction. Each color corresponds to a specific wavelength of light, which is determined by the energy bandgap of the semiconductor material. For example, red LEDs typically have a lower knee voltage (around 1.8-2.2 volts) compared to blue or white LEDs (around 3-3.5 volts), as the energy required to emit light increases with shorter wavelengths. This variation in knee voltage is a result of the differing energy levels associated with the electrons in the semiconductor materials.
Trying to make some indicators for a bike and am going to use 1.5 volt leds and a 12 volt 11ah battery by putting 8 leds in series was wondering whether resistors are needed not to short the leds?
Resistors will be needed in all cases when driving LEDs from a voltage source, unless you are using LEDs that already have a built in current limiting IC inside the package (a few do these days, for example I have some blinking LEDs that need no resistor they have a blinker IC built in that also limits current).However you have another problem that you obviously are not aware of. 8 LEDs rated at 1.5V in series totals exactly 12V. But your battery is only rated at 12V. As the battery discharges its voltage slowly drops, the moment it drops under 12V all the LEDs will turn off! I strongly recommend that you use no more than 7 LEDs rated at 1.5V in a circuit powered by a 12V battery, so that the battery can actually gets a chance to discharge beyond its knee voltage. In this case the resistor will drop the remaining voltage, whatever it is depending on the charge state of your battery.
How are LED TVs made?
by growing an array of different color LEDs and driver transistors on a glass sheet. each pixel gets a square array of 4 LEDs: red, green, blue, green. the glass sheet is then wired to the TV circuits. the glass sheet (screen) is effectively a super giant IC.
What is the lumen loss of led lamps?
LEDs will typically reduce their light output throughout their life after an initial increase above the rated light output.This degradation will usually be a near-linear reduction.Well-made LEDs will not normally fail catastrophically, but drop in their output until they are no longer useful.High quality LEDs are typically rated to drop to 70% of initial light output after 50,000 hours for white LEDs, and 100,000 hours for all other colours.
Can a nokia bl-5j 3.7 volt battery be used to power LED's safetly and how?
A: It sure can but what is voltage iof the LEDS 3.2 V then you need to drop 3.7 to 3.2 v at ~20ma .5v / 0,02=27 ohms in series the LEDS are 1.8 you need 3.7- 1.8/.02= 100 ohms in series. The warning is the life of this setup is going to be short lived after the battery drain off the battery needs recharging if so it is better to supply the LEDS from the charger directly will last until the LEDS QUIT FUNCTIONING
How are LEDs different from other artificial light sources?
The difference is that LEDs use less electricity.
What is the length of a pair of scissors?
They can be different lengths. YOU say they can be shown in different lengths but i need to know what particular lengths
What is the triangle that has two different lengths?
A SCALENE triangle has all three sides different lengths.
What are the lengths of the sides of an obtuse triangle?
The 3 sides have different lengths
What makes up the lights of a set of traffic lights?
Incandescent light bulbs are used, in addition to LEDs. LEDs or laser emitted diodes, produce the different colours with different electricity molecules mixing with the oxygen in the air
How long was each episode of fawlty towers?
There were 12 episodes of Fawlty Towers. Series 1, six episodes first broadcast on BBC television in the UK weekly from 19th September 1975. Series 2, six episodes broadcast weekly from 19th February 1979.
Which is a more powerful light - 95 leds or 128 leds?
If your compairing apples to apples like 3 watt leds to 3w leds then 128. The more leds the higher the power.
Lengths of a scalene triangle sides?
All three sides have different lengths.
Why do we have varying day lengths?
The tilt of the earth causes different day lengths.
How much energy does a led use per hour?
LEDs come for different power ratings. Miniature LEDs use between approximately 40-90 mW. High-power LEDs - used for illumination - can use hundreds of watts per square centimeter.
Why germanium and silicon are not preferred in LEDs?
A: Because the element has different property as gallium arsenide.
How many lengths do you swim for a gold?
That does not matter. There are different events which consist of different lengths. You just have to place 1st in an event.
