LED'S question????????
#1
LED'S question????????
I have a led wiring question. I知 using 12v leds 5mm 10,000 mcd and 220 ohm resistors and they seem to work fine but when I connect more leds they start to dim. So my question is, should I use a different resistor when I知 connecting more then 5 leds? Witch resistors you guys recommend? And if I can connect more then 20 leds witch resistors to use? If some one has wiring diagram please email me @ starinskiy@yahoo.com. Thanks!!!!!!!!!!!!!
#2
Originally Posted by Talyan03
I have a led wiring question. I知 using 12v leds 5mm 10,000 mcd and 220 ohm resistors and they seem to work fine but when I connect more leds they start to dim. So my question is, should I use a different resistor when I知 connecting more then 5 leds? Witch resistors you guys recommend? And if I can connect more then 20 leds witch resistors to use? If some one has wiring diagram please email me @ starinskiy@yahoo.com. Thanks!!!!!!!!!!!!!
Impossible, I call
![BS](https://maxima.org/forums/images/smilies/bs.gif)
You need to find what the working voltage if of the LED (Vf). So let's say that we are using a single LED. Our working voltage is 13.4V, let's call our Vf 1.8. So...
13.4 - 1.8 = 12.6 V left in the line
Now, we need to consider how many milliamps (mA) are needed to actually light the LED...most run full capacity @ 20mA (Yours might be different). Now, simply divide the desired current into our voltage supply and we get the ohms-resistance needed.
12.6 / 0.020 = 680-ohms.
680ohms / 220ohms/resistor = +3 resistors to run the LED SAFELY.
Now, let's also consider if we ran 7 LEDs in series. 13.4 - (7*1.8) = -1 V. So now, we don't need a resistor.
CONCLUSION: Find out what your Vf is before you start sourcing out power supply insufficencies.
#3
Yeah, just what Metal said. Also, you can wire them safely like 3-4 LED's in "series" on one resistor, before you can actually see a difference in brightness.(Or, maybe even more, depending on the resistor and LED of course). I did this with the shifter lamp under the A/C unit. Just make sure you achieve a positive and negative lead when you tap into the resistor and 12V lead. I used 3mm 5000 LED's for this setup and it's enough brightness at night.
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