Will the led be affected by a higher current but same voltage?

Question

I can provide the same voltage the led requires, but I plan to connect several leds in parallel. I don't understand how I can control the mA for each led. Say the source provides 70 mA, and I only connect to leds, does this affect the life of the leds?

Answer 1

Just connect the proper voltage across the LED, and by Ohm's law, it will automatically take appropriate current. Connect as many as the supply can handle in parallel, and it will be fine, as long as the voltage is equal to or less than the lowest max voltage rating of the diodes.

A word of warning though, you are playing with fire a little bit here. The forward biased curve of LED voltage vs. current is fairly steep. Thus, if the voltage is a little bit above the rated value, current grows rapidly with excess voltage and can be huge and smoke the LED. This is why some other Yahoo-ers incorrectly believe you must have a "current limiting" resistor. This is used because it is a simple and forgiving circuit, however, it is not necessary if you understand the physics and respect the manufacture ratings. I do like to put a small resistor, like 1 Ohm or even less, in series with the diode as a current sensor (not to limit current). You can measure the voltage drop across the resistor to directly determine the current by Ohm's law, thus verifying the current is OK.  Measure the resistor accurately before putting it in, then use I = E/R to determine current.

The LED is not actually limited by voltage or current, it is really the power that causes problems. By verifying power = volts * amps is below the diode rating, you assure it will last a long time. You can also put the power supply voltage a little below the rated LED voltage, to make sure you are safe.

Answer 2

This does not work. You need a resistor in series for each LED, and you should drop at least 2 volts across the resistor.

Leds with a voltage applied to them will blow up or not light at all.

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Answer 3

no. The current is higher because it is divided across the parallel paths. The current through each path will remain the same with or with out another in parallel. Components in parallel are called current dividers and in series are called voltage dividers.  

If you do not change the voltage, the led current will remain constant.

Answer 4

If you are connecting LED's in parallel each LED should have a current limiting resistor.

If you connect LED's in series only one current limiting resistor is required.

see

http://www.kpsec.freeuk.com/components/l...

http://answers.yahoo.com/question/index?...

http://en.wikipedia.org/wiki/LED_circuit