well, a quick question,
could i connect 12v to a LED?
i will use resistor to limit current to 25mA, but just wondering would LED could accept 12V?
or it will kill the LED?
If conncted with correct polarity, the diode voltage is self limiting (if a suitable resistor is present), but reverse polarity would immediately destroy the LED. If there is any risk of wrong supply polarity, you should connect a diode, either in forward series connection or in reversed antiparallel connection to the LED.
P.S.: You can also use a two pin bi-color diode, it shows different color with reversed supply, but is effectively protected.
By placing a limiter resistor in series the voltage drop across the resistor will bring the voltage across the led to its nominal value. Leds are current driven, not voltage driven. No problem in doing that with a resistor. The value should be near 470Ω or 680Ω.
If conncted with correct polarity, the diode voltage is self limiting (if a suitable resistor is present), but reverse polarity would immediately destroy the LED. If there is any risk of wrong supply polarity, you should connect a diode, either in forward series connection or in reversed antiparallel connection to the LED.
no wrong polarity risk for my case.
therefore, just double confirm, i could just connect directly 12V to my led. to limit current to 25mA, i will need to add a 480Ohm resistor in series with the LED.
am i correct?
thanks.
Added after 2 minutes:
thanks bro FvM and pauloynski
i got the point.
now i could proceed with my project. thanks for fast reply.
Yes, just confirm that 25mA is the right current for you led. Also, note that depending on the led color the voltage across it is slightly different. Red=1,9V, Green = 2,3V and Blue = 3,6V (may differ depending on the brand and current). The value you´ve choosen seems to be safe for all types.
Hey,
What you wrote before was correct. Choosing resistor you should remember about power dissipation on it. I don't know what is the LED you picked up. Suppose drop in voltage on LED is 1.4V. (12-1.4)*24mA=0.25W. So you have to choose current limit resistor which is capable dissipate 0.25W.
For a LE to work from 12 volts I have been using a 1K to be on the safe side and I have been running a LE of 12 volts AC for over 4 years works well after all ;all that we are doing is converting AC to DC