I'm wondering what will happen if more or less voltage is given to a LED light, like a single diode. Example: if the LED is stated as a 12V, what would happen if i attach it to a 6v power supply?
2007-03-17 22:02:37 · 6 answers · asked by martystoyanov 2 in Consumer Electronics ➔ Other - Electronics
It has to have a certain amount of voltage to actually work, but once it reaches that voltage, it will glow, but not as bright without the right voltage. too much will burn it.
2007-03-17 22:07:20 · answer #1 · answered by M00ND0CT0R 6 · 0⤊ 0⤋
The LED will have a "forward voltage", which is the voltage dropped across the LED when it conducts. You only need THAT voltage to make the LED conduct and give light. The excess voltage is shorted by the LED and will drop on the current limiting resistor that you HOPEFULLY accompanied the LED with(pull up, pull down).
The LED will also have a "nominal forward current" rating, which states the optimum current needed to achieve the rated millicandela(brightness) of the LED. More current, the brighter the LED will be, to a point, but the life-span of the LED will be reduced. The lesser the current, the less brightness you get from the LED, but it should last longer than excessive current.
Example:
So if you have an LED with a forward voltage of 2V connected across a 12V source, 12V will be dropped across it, but the LED is being damaged because while only 2V are needed to light it, you have 12V with no current limiting. Therefore you have a smoke emitting diode.
If you have a 2V LED with a current limiting resistor in series, across a 12V source, you will have 2V dropped at the LED, and 10V dropped at the resistor, with 10V/R current flowing.
If you have the forward voltage rating, the forward current rating, and the power supply voltage, designing your circuit is easy.
The equation is R = (Vsupply - Vforward)/I forward
Example:
You have a 12V source and an LED who's data sheet states a forward voltage of 1.6V and a forward current of 150mA.
R = (Vsupply - Vforward)/I forward = (12V - !.6V)/150mA = 69.3ohms.....go lower R for brighter, higher R for dimmer
2007-03-20 14:54:32 · answer #2 · answered by joshnya68 4 · 0⤊ 0⤋
If an LED is stated as having a forward voltage of 12v and you apply 6v then it simply should not light at all. The stated voltage should be the required voltage to break down the internal "barrier" to current.
The main thing that affects the brightness of an LED is the current supplied, higher current means brighter LED but too high a current will turn it into an SED, or Smoke Emitting Diode. Use current limitting resistors to prevent burnout... http://led.linear1.org/1led.wiz
2007-03-18 05:42:01 · answer #3 · answered by PaiMina 1 · 0⤊ 0⤋
The 12 volt rating is a suggested highest voltage that should be applied across it. Less voltage wont hurt the led although it wont be as bright as it could be, as long as you reach the voltage accross the enclosed junction which can be as low as .6V you can vary the voltage right up to 12 volt. but i wouldnt push it too far over the rated voltage as they will burn out.
They may be pushed a little higher as long as you limit the current with a current limiting resistor.
Hope that Helps
2007-03-18 05:36:16 · answer #4 · answered by razerally 2 · 0⤊ 0⤋
i've seen that happen. it does that all the time with your DSL modem or the HDD volume boot LED (the red or orange light in the front of the pc) it usually has a low glow or it flickers depending on how much you give it.
2007-03-18 05:27:36 · answer #5 · answered by ? 2 · 0⤊ 0⤋
Burn @ LOWER LIGHT if VOLTAGE is LOWER
TOO MUCH VOLTAGE BURNS 'em UP or MELTS 'em
2007-03-18 05:14:28 · answer #6 · answered by NOKIA 6103 By T*MOBILE 3 · 0⤊ 0⤋