3 volts DC and some high intensity LEDs .. do I need resistors?

[smp]

I'm making a strip light, I have 5 whites and 5 blues .. I have a 3 volt DC brick (well it's one of those multi ones, but it's set to 3 volts) .. i'm hooking them up in parallel (is this parallel, one ground and a bunch of power leads?) ..

do I need resistors on the LEDs? and if so, which resistors?
Thanks

 

[Navid]

Can you explain what you want to do a little more?

Do you want all the LEDs to be on?

Parallel means you connect lead A of all LEDs together and you connect lead B of all LEDs together. Series means you connect lead B of LED 1 to lead A of LED 2 and lead B of LED 2 to lead A of LED 3 .....

The only way you can turn these on without burning them with a 3V source is to either use resistors or to put them in series. An LED needs about 0.6V when it turns on. So, you can put 5 of them in series and connect 3V across.

But, the best thing to do is to get resistors for limiting the current. You need to find out how much current one of those LEDs needs to turn on with the brightness you are happy with. Let's say that is 100uA (this is just an example). Then, you know that you need to have the remaining voltage (3-0.6=2.4V) across the resistor. The resistance will be voltage divided by the current, or 2.4/100uA=24k Ohms.
You will need as many resistors as you have LEDs.

An LED is a diode (Light Emitting Diode). A diode has two leads, anode and cathode. Current enters the Anode and exits the cathode.

Or, you can just try a 56k Ohm resistor in series and see if it turns on. if it does not use a smaller resistor. If you do not use a resistor, a 3V supply can burn the LED.

Edit:
The main advantage of the resistor (other than not burning the LED) is that you can choose the brightness by selecting the resistor value.