LEDs wiring and resistors (please help)

[Keith]

Above is a quick drawing of how i want to lay out and wire-up some LEDs. From front left to right is about 3 feet in length.

The white dots are 5mm White LEDs. The only info i have on them is the following:
5mm Bright White LEDs
12V DC
20 mA
High Intensity - Low Power.

The two green and one red dot are 3mm green and red LEDs. Info:
High Brightness 3mm LEDs
12V DC
20 mA
High Intensity - Low Power

I am trying to find out the voltage of these LEDs, but so far, the seller has not sent me a reply after me asking three times.

Can anyone who knows about wiring LEDs help me wire these up. I don't know what resistors i need or where i should fit them.
These are going inside a model and can never be replaced once its built, so i need them to be wired up properly, with the correct resistors and the most suitable power supply.
I need to make it so if one led fails, the others still work.

Please help!

Keith.

 

[Scott Graham]

I used this for a recent 3 LED combination in an a-wing build. It helped a lot, and even told me what resistor(s) is needed:

http://led.linear1.org/led.wiz

 

[tim]

The white LEDs probably have a forward voltage between 3 and 5 VDC; the other LEDs should have a forward voltage of around 2-2.5 V. As for the resistors, the values needed will be dictated by the voltage of the power supply and whether the LEDs are wired in series or parallel. I'd probably recommend stringing 3-5 LEDs in series to create a "module" and then wiring the "modules" in parallel. This would have to be done correctly so that the total voltage drop (basically the sum of the forward voltages for all component LEDs) for each "module" is the same so that you don't have to play around with different resistor values.

 

[Keith]

Thanks.

I keep seeing wiring diagrams showing the to main + and - wires, with each LED branching off them.
Is there any reason why all the leds + wires can't all join together onto the main + wire using a junction block if i put a resistor on each LED?
This seems much more simple and tidy to me, rather than breaking into the main + wire multiple times and having to solder and heat shrink every LED.

Keith.

 

[feek61]

Keith,

I always use this LED arry wizard which will show you the resistors you will need for an array or just single LEDs:

http://led.linear1.org/led.wiz

Also if you look on this site you can get the specs from the LEDs and match them to the ones you have (or get close enough):

http://www.superbrightleds.com/leds.htm

Click on the left side for the specs.

I hope this helps!