All About Leds
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There's alot of misunderstanding and rumors running around here about LEDs. I decided to write a guide on Facts about LEDs. It's kind of frustrating for me to talk to people sometimes and this is a topic I've been dealing with alot lately. So here goes.
First to dispell rumors...
-LEDs drop little voltage compared to incandescants:
LEDs drop anywhere between 1.2V to 3.6V even without a ground applied, which means alot to any type of computer in your car. Incandescants do not drop voltage without ground.
-LEDs don't use current:
LEDs drop a certain ammount of voltage to foreward bias themselves. Then the current draw starts, usually about .02-.03Amp.
-LEDs are brighter:
it depends on the circumstances. LEDs are actually less bright overall but more focused. Incandescants are brighter overall, but way less focused. think of an LED like a flashlight, and a incandescant like a light bulb.
-LEDs light comes from the filament:
The "filament" in an LED is called a P/N junction. not really a filament, more of a mineral in a dish between 2 semiconductors.
-sounds like a fancy incandescant:
NO!!!!
A incandescant works like a toaster filament. you run electricity through it and it gets hot and glows.
A LED on the other hand, has a positive/negative junction called a P/N junction. It takes a certain ammount of voltage for the potential difference between the P side and the N side to be felt (FWD bias). After that voltage requirement is met, electrons jump across (current) and they loose energy in the gas in the dish. The energy is reflected out of the dish and to the front of the LED, where it is focused and expelled.
here is an LED
1.Voltage goes in the annode to the P junction.
(foreward bias voltage is lost, all else is passed)
2. Electrons in the cathode, N junction see the voltage sitting at P and start hopping across
(current is lost in the form of energy photons... Wave partical duality)
3. Photons/light are then shot out in all directions but contained by the fiberoptic properties of the LED.
4. Light is bounced around mulitple directions but eventually focused out the tip of the LED.
Voltage:
LEDS will act as a voltage barrier until foreward bias voltage is achieved (1.2V). A LED has no internal resistance after foreward bias is overcome. This is why you need a resistor. A LED drops very little voltage after foreward bias and has very little resistance as well. The resistor drops total wattage and turns it into heat.
Paralell:
Mass amounts of LEDs may be run in a seperate paralell circuit with battery voltage on one end and ground on the other. You don't want to try to put them in series of more then 4 even with correct calculations because of their cumulative foreward bias voltage. They can be joined together if calculations are done correctly
This is the same thing but has double the current in one resistor. It's still a very small ammount though. .04Amps
Resistance:
pretend this is about 13V worth of fwd bias in these resistors. With the vehical off, they wouldn't work. with the vehical on, they will blow up. This is because once the foreward bias is reached, at least one will blow up because there is no current regulation. 1V = 1A without resistance so these LEDs will have about 25X the ammount of current they require to light up running through them.
Advantages:
The universal advantages of LEDs over incandescants are low power consumption (wattage), light concentration, and frequency concentration. power concentration makes for less power, not through voltage used, but through the total amperage it takes to power an LED. The light concentration means they are naturally more focused then an incandescant, meaning that the LED shines in a small area. The frequency concentration means that blue is blue and red is red, whereas a white light through a diffuser will be slightly orange and slightly purple. frequency(color) is determined by the material in the P/N junction. For blue LEDs it's usually a slightly radioactive but harmless material.
First to dispell rumors...
-LEDs drop little voltage compared to incandescants:
LEDs drop anywhere between 1.2V to 3.6V even without a ground applied, which means alot to any type of computer in your car. Incandescants do not drop voltage without ground.
-LEDs don't use current:
LEDs drop a certain ammount of voltage to foreward bias themselves. Then the current draw starts, usually about .02-.03Amp.
-LEDs are brighter:
it depends on the circumstances. LEDs are actually less bright overall but more focused. Incandescants are brighter overall, but way less focused. think of an LED like a flashlight, and a incandescant like a light bulb.
-LEDs light comes from the filament:
The "filament" in an LED is called a P/N junction. not really a filament, more of a mineral in a dish between 2 semiconductors.
-sounds like a fancy incandescant:
NO!!!!
A incandescant works like a toaster filament. you run electricity through it and it gets hot and glows.
A LED on the other hand, has a positive/negative junction called a P/N junction. It takes a certain ammount of voltage for the potential difference between the P side and the N side to be felt (FWD bias). After that voltage requirement is met, electrons jump across (current) and they loose energy in the gas in the dish. The energy is reflected out of the dish and to the front of the LED, where it is focused and expelled.
here is an LED
1.Voltage goes in the annode to the P junction.
(foreward bias voltage is lost, all else is passed)
2. Electrons in the cathode, N junction see the voltage sitting at P and start hopping across
(current is lost in the form of energy photons... Wave partical duality)
3. Photons/light are then shot out in all directions but contained by the fiberoptic properties of the LED.
4. Light is bounced around mulitple directions but eventually focused out the tip of the LED.
Voltage:
LEDS will act as a voltage barrier until foreward bias voltage is achieved (1.2V). A LED has no internal resistance after foreward bias is overcome. This is why you need a resistor. A LED drops very little voltage after foreward bias and has very little resistance as well. The resistor drops total wattage and turns it into heat.
Paralell:
Mass amounts of LEDs may be run in a seperate paralell circuit with battery voltage on one end and ground on the other. You don't want to try to put them in series of more then 4 even with correct calculations because of their cumulative foreward bias voltage. They can be joined together if calculations are done correctly
This is the same thing but has double the current in one resistor. It's still a very small ammount though. .04Amps
Resistance:
pretend this is about 13V worth of fwd bias in these resistors. With the vehical off, they wouldn't work. with the vehical on, they will blow up. This is because once the foreward bias is reached, at least one will blow up because there is no current regulation. 1V = 1A without resistance so these LEDs will have about 25X the ammount of current they require to light up running through them.
Advantages:
The universal advantages of LEDs over incandescants are low power consumption (wattage), light concentration, and frequency concentration. power concentration makes for less power, not through voltage used, but through the total amperage it takes to power an LED. The light concentration means they are naturally more focused then an incandescant, meaning that the LED shines in a small area. The frequency concentration means that blue is blue and red is red, whereas a white light through a diffuser will be slightly orange and slightly purple. frequency(color) is determined by the material in the P/N junction. For blue LEDs it's usually a slightly radioactive but harmless material.
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ok wierd topic
not sure if this belongs in offtopic but im not really sure where it belongs so im gonna move it to ICE
you know alot about electronics but cant post a pic right lmao.gif
i also deleted the duplicate post
not sure if this belongs in offtopic but im not really sure where it belongs so im gonna move it to ICE
you know alot about electronics but cant post a pic right lmao.gif
i also deleted the duplicate post
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Vehicle: 2001/Hyundai/Tiburon
thats cool and all, but nobody here needs to know about that/care unless there in a physics or elec. course of study.
you should have got into how the p and n type semiconductors are made by adding impurities, or "doping".
there is no gas in a led though. the photons are emitted directly from the crystalline semiconductor material as the electrons lose energy recombining with a positive charge. here electrical energy is converted to electromagnetic energy, releasing a photon. the color of tyhe photon is determined by the distance of the depletion region and chemical makeup of the semiconductor material. then there are mirrors and stuff to reflect it out and focus it.
and whats really cool, is that if you hook up a led in reverse bias to a meter, you might actually see a small amount of voltage. this is because incoming light photons around it can actually be absorbed by electrons, causing them to be transferred into the conduction band.
i just took a test in my phy3 class on modern physics, so this stuff is fresh in my mind. better make use of it while its still there.
you should have got into how the p and n type semiconductors are made by adding impurities, or "doping".
there is no gas in a led though. the photons are emitted directly from the crystalline semiconductor material as the electrons lose energy recombining with a positive charge. here electrical energy is converted to electromagnetic energy, releasing a photon. the color of tyhe photon is determined by the distance of the depletion region and chemical makeup of the semiconductor material. then there are mirrors and stuff to reflect it out and focus it.
and whats really cool, is that if you hook up a led in reverse bias to a meter, you might actually see a small amount of voltage. this is because incoming light photons around it can actually be absorbed by electrons, causing them to be transferred into the conduction band.
i just took a test in my phy3 class on modern physics, so this stuff is fresh in my mind. better make use of it while its still there.
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Joined: Feb 2009
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grrrrr... like 1/2 of the thing was deleted and a picture went down.
You're right. the color is produced by the chemical makeup of the latice structure which is not a gas. You can make that change if you want.
The first one was created on accident because of a diode which split in two and only worked sometimes. Now the PN junction is straight latice.
I didn't want to go too in depth about it all though. I really just wanted to write a little about these LEDs because what something means to one person means something completely different to another. I've talked to alot of people about LEDs on here recently and have run into communication barriers. I hope i at least made an interesting and beneficial artical.
QUOTE (tibby01 @ Dec 12 2005, 08:29 PM)
thats cool and all, but nobody here needs to know about that/care unless there in a physics or elec. course of study.
you should have got into how the p and n type semiconductors are made by adding impurities, or "doping".
there is no gas in a led though. the photons are emitted directly from the crystalline semiconductor material as the electrons lose energy recombining with a positive charge. here electrical energy is converted to electromagnetic energy, releasing a photon. the color of tyhe photon is determined by the distance of the depletion region and chemical makeup of the semiconductor material. then there are mirrors and stuff to reflect it out and focus it.
and whats really cool, is that if you hook up a led in reverse bias to a meter, you might actually see a small amount of voltage. this is because incoming light photons around it can actually be absorbed by electrons, causing them to be transferred into the conduction band.
i just took a test in my phy3 class on modern physics, so this stuff is fresh in my mind. better make use of it while its still there.
you should have got into how the p and n type semiconductors are made by adding impurities, or "doping".
there is no gas in a led though. the photons are emitted directly from the crystalline semiconductor material as the electrons lose energy recombining with a positive charge. here electrical energy is converted to electromagnetic energy, releasing a photon. the color of tyhe photon is determined by the distance of the depletion region and chemical makeup of the semiconductor material. then there are mirrors and stuff to reflect it out and focus it.
and whats really cool, is that if you hook up a led in reverse bias to a meter, you might actually see a small amount of voltage. this is because incoming light photons around it can actually be absorbed by electrons, causing them to be transferred into the conduction band.
i just took a test in my phy3 class on modern physics, so this stuff is fresh in my mind. better make use of it while its still there.
You're right. the color is produced by the chemical makeup of the latice structure which is not a gas. You can make that change if you want.
The first one was created on accident because of a diode which split in two and only worked sometimes. Now the PN junction is straight latice.
I didn't want to go too in depth about it all though. I really just wanted to write a little about these LEDs because what something means to one person means something completely different to another. I've talked to alot of people about LEDs on here recently and have run into communication barriers. I hope i at least made an interesting and beneficial artical.
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Vehicle: 2001 Hyundai Tiburon, 2004 Kia Sorento, 2010 Kia Soul
Okay, i've had enough of this shit.
CLOSED until 01Tibby can get to it.
DrivingTibNaked, enjoy the evening off.
CLOSED until 01Tibby can get to it.
DrivingTibNaked, enjoy the evening off.