Quick resistor question

[POPEYE]

Can anyone tell me what value resistor i would need to connect a ultra bright led to to give less than 12volt? say 9-10v so it's not so bright, running other leds from a 12v source but just need to cut the power down to these two (side lights on a model, amber), off to maplins on the way out for tonight before they shut but thought i'd ask so i can quite what i want instead of relying the spotty c### behind the counter
i thank you

[Apache]

The guys at the electronics counter are usually pretty clued up.

These days it isn't always so simple as shooting for 20mA, though its usually a pretty good start. For 12v it is 600 ohms (I think 620 is nearest value), so increase that value to reduce the brightness.

[Apache]

Might do. With LEDs its a matter of limiting current really, so it would be a case of suck it and see depending on the design of the dimmer.

[POPEYE]

Cheers, ok the bloke at maplins was very good, as he said he's guessing as i did'nt know the forward voltage or limiting voltage of the two leds, so he sold me some 680's, i'll give em a try, btw when one orderes leds from goodwills anyway ya get 470ohm resistors for running on 12v thats the ultra-bright leds