# LED info - 12V battery wired to four 3V LEDs in series...

This preview shows page 1. Sign up to view the full content.

Two resistors are connected as shown in the following diagram: The output voltage V out is related to V in as follows: As a simple example, if R 1 = R 2 then Any ratio between 0 and 1 is possible. Luminous flux lumen cd * sr = lm R = (V1 - V2) / I R = (4.5V - 1.7V) / .02 A = 140 ohms I = LED current (when wiring in parallel, multiply the current of one LED by the total number of LEDs) 20mA x 2 = 40 mA = .04A (we had been using 20 mA in our other calculations but since wiring LEDs in parallel draws more current I had to multiply the current that one LED draws by the total number of LEDs I was using. 20 mA x 2 = 40 mA, or .04A. Whenever using a resistor on an LED it should get placed before the LED on the positive electrode. If you wire a whole bunch of LEDs in series, rather than dividing the power supplied to them between them, they all share it. So, a
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 12V battery wired to four 3V LEDs in series would distribute 3V to each of the LEDs. But that same 12V battery wired to four 3V LEDs in parallel would deliver the full 12V to each LED - enough to burn out the LEDs for sure! Wiring LEDs in parallel allows many LEDs to share just one low voltage power supply. Wiring in parallel only works if all the LEDs you are using have exactly the same power specifications. Do NOT mix and match different types/colors of LEDs when wiring in parallel. http://www.instructables.com/id/E9NFEFO2ZGEV2Z9QKZ/?ALLSTEPS The package didn't come with a 140 ohm resistor but it did come with a 150 ohm one. Its always better to use the next closest value resistor greater than what you calculated. Using a lower value could burn out your LED....
View Full Document

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern