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question about led's

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fiji

Member
Joined
Jul 14, 2002
Location
berlin
ok well im not very familiar with leds or the theory behind them they just seem to be a big ball of smart people things


ok well anyway getting to my question


would a led lower the voltage of a line? i dont think they would i mean it just wouldnt make sense but then again im like :rolleyes:

cuz i was on this site where a guy put 3 LEDS in a series on his 12v line w/o a resistor and they were only 5v leds....


also what does forward/backwared voltage mean?
 

1-Man-Army

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Oct 18, 2002
Location
Ontario Mississauga
thats because led=load which means it use up the energy which means u dont need a resistor (is they were linked together)
about forward and back ward i think he means the elcetricty not going in a straight line as in its not stable correct me if im wrong but thats what i tihnk he meant by forward and back wards
 
Last edited:
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fiji

fiji

Member
Joined
Jul 14, 2002
Location
berlin
what = load?


well erm... wouldnt that just be wattage and not potential energy diff?


garr i dont know naything but i dont know what you mean they are load


ok basically what im trying to figure out is what do the forward/backward and rated voltages mean in practical terms
 

1-Man-Army

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Oct 18, 2002
Location
Ontario Mississauga
the led light emitting diode its a load means it uses up the energy meaning lowering the currents or to put it in a simple way what i mean is the led eats up the energy eg u have 12v right?
a led which use 3 volts whats gonna happen?
the led eats up the 3 volts but gets shoved with that extra 7volts which will blow it up, but if they were linked to getter then each led takes 3 volts out of 13 volt
 
OP
fiji

fiji

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Jul 14, 2002
Location
berlin
well i dcant find the link and im just over all confused right now lol

but i get the part of losing the voltage


but not sure kidna well
 

Butmonkey

Registered
Joined
Nov 9, 2002
Correct me if I'm wrong, but I believe voltage is simply potential for a current. I feel confident when I say that no, it wouldn't cause a voltage drop, unless the LED is resistant. If it is, the voltage drop is probably negligible.
 

1-Man-Army

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Oct 18, 2002
Location
Ontario Mississauga
ok since ur a bit confused let me give atemp number 3 what i mean is if u take a light bulb and soldered the wires on then u add one 5v battery its pretty dim now addanother battery u gain more volts right? thats serries circut so if u do the opposite like how u read sum were, were this guy hooked 3 leds in the line its almost the same as the light bulb thing's example. so instead of adding more volts u add more things like led which will act like 1 resistor taking away the electricty so the more load(led,light bulb or sumtihng that use electrcity hdd,cdrom) u add the more it will use up the current which means u do not need resistors cause u used up all of the electricity which is not over powering the leds
so do u get it now?
if u still dont then heres a very short example that u might get
if u have 5v and u no 1 led takes 3v right? so what do u do and plus u wanted to add 3 leds right? if u added the resistor and then added 3 leds not enough power u can see led 1 bright led 2 will be less bright as led 1 and led 3 will be dimmed so if u have alot of loads(leds light bulbs etc) that u need a resistor then u add a few more leds and it will use up all the current and ur done no need for resistors
 

Veland

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Aug 13, 2001
Location
Bergen, Norway
..and forward voltage is the maximum voltage that can go through it "the right way". But the LED is a light emitting DIODE, so the reverse voltage is the maximum voltage it can "stop" without taking damage.
 
OP
fiji

fiji

Member
Joined
Jul 14, 2002
Location
berlin
1-Man-Army said:
ok since ur a bit confused let me give atemp number 3 what i mean is if u take a light bulb and soldered the wires on then u add one 5v battery its pretty dim now addanother battery u gain more volts right? thats serries circut so if u do the opposite like how u read sum were, were this guy hooked 3 leds in the line its almost the same as the light bulb thing's example. so instead of adding more volts u add more things like led which will act like 1 resistor taking away the electricty so the more load(led,light bulb or sumtihng that use electrcity hdd,cdrom) u add the more it will use up the current which means u do not need resistors cause u used up all of the electricity which is not over powering the leds
so do u get it now?
if u still dont then heres a very short example that u might get
if u have 5v and u no 1 led takes 3v right? so what do u do and plus u wanted to add 3 leds right? if u added the resistor and then added 3 leds not enough power u can see led 1 bright led 2 will be less bright as led 1 and led 3 will be dimmed so if u have alot of loads(leds light bulbs etc) that u need a resistor then u add a few more leds and it will use up all the current and ur done no need for resistors

but current amps, or the watts they take is totally diff than a voltage drop


but i think you mean it will lower the voltage or potential energy.... so your saying that like a led has resistance itself like a good bit of resistance so that 3 of them would be quite alot of resistance

ok so if thats true is there anyway to calculate how much resistance a led takes away
 

Vulpes

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Dec 29, 2002
Location
Denver, CO
like 1 man Army is explaining, LED stands for Light Emitting Diode, and it works by moving electrons through special material, on the fat side the electors are being generated (thus it being (-) side) and on the other one electrons are being taken away, thus causing electorns jump from the fat side while emitting light and very smal amount of heat.
The "Jump" requires Potential (i.e. Voltage) and also generates resistance. LEDs are very efficient, almost all energy that it "eats up" turns into light, if LEDs are overloaded, they heat up, when they heat up, you have a problem.
What the guy did by hooking 3 leds in series is plit the voltage among 3 leds. Since you have 12 volts and 3 "resistors" on the line, each gets 4 volts. Thats how much ultra bright red/white LED's eat up. Blue requre less voltage. The other way to hook up led's in a computer is take a 60 ohm resistor (so the voltage drop after it would be 4.2-4 volts) and supply that to led. The usual rating for leds is 3-4.2 Volts, and 5 is severe overvoling causing overheating.
 
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fiji

fiji

Member
Joined
Jul 14, 2002
Location
berlin
thanks alot, i get it now

somewhat ... :)


well i atleast understand what i need to do, to put some cool led's in my case ehehe and thats all that matters