Hi Bombero
I used lots of LEDS on my RMS Olympic and they were wired in parallel in several banks to allow for the different current required for different size Leds 3mm and 5mm. You will need a voltage reducer to provide the max 3v required and as others have indicated some Leds require lower voltages. They all require a current limited source to prevent instant destruction of the junction. I used the LM317 voltage reg chip in four separate units (two for port and two for starboard) and connected this through a remote controlled 12v switch which allowed me to dim the lights when on display. There are many cheap voltage converters available so you don't need to build your own. I attach a pic of the units and the model FYI. It's 9ft long and has Led's in each porthole. I can provide details of the electonics if you are interested. Good luck
Dave 976

Hi
You could try a voltage reducer from component shop, that way you remove the resistor.

Strained my eyes Googling it.

https://www.componentshop.co.uk/led-exp/
This gives you some idea what's required

https://www.componentshop.co.uk/led-exp/

🔗

HI yes sorry I wrote diode instead of resistor, not sure what you need resistor wise but pre wired diodes normally have coated wiring.

First, what is your supply voltage.
Leds the colour of the led determines it's driving voltage.
White led requires 3 volts to light it.
If you have a 6volt dc supply , you can connect two in series which gives three volts across
There is quite a lot info on the Web about this and the use of resistors to drop the voltage required by the led.
It's using ohms law to calculate the resistor size but you need the find the spec for the led.
Led are polarity sensitive as well.

LEDs must have a dropping resistor, to keep them from destroying themselves by overdrawing .02 ma, each. Three LEDs, in series, will have a different size dropping resistor, than a single one. As to series or parallel connection, all in parallel, could be dropped by one resistor, of a slightly higher wattage(usually not a issue), mostly a decision on how complicated the plan becomes. Someone mentioned using a diode, did they really have a diode? A diode has a drop of about 1 1/2v, no resistance, and isn't a help in this decision. Does this help? kb

You likely already know, LED's are polarity sensitive so if some don't light reverse it's polarity.

HI They are wired like that on my model railway station platform lights. Run on 12 volts through a resistor to illuminate three lights. I did buy a three volt power supply in the end. If like mine the wires are coated with enamel.

As long as the resistors are first from the battery I can't see that series or parallel makes any difference.

You could cheat and get a string of white lights from poundland with a 2 x AA battery holder