resistors

[bluedepot]

can someone link me to some suitable resistors?

i have a 16v output, i want to use it for signals and lighting (that i think require 2v outputs - i don't want them too bright so want good resistors)

i have no idea about electronics...

cheers


tim

[davieb]

hi tim

when you say you have a 16v supply is that AC or DC also are the bulbs LED's or normal bulbs

dave 

[EtchedPixels]

What are you actually trying to do ? With a bit more detail ?

Resistors don't simply make the voltage go away so it's not quite so simple - especially if you only want 2v, and if you need DC. And for lighting you *want* DC. LED lights need DC and ye olde filament lights last vastly longer on DC than AC (a point the manufacturers never seem to remember to mention)

What are you trying to drive ?

Alan

[bluedepot]

hi

i have 16v dc output

i want to power colour light signals (CR, Berko) and then also some yard lights (i'll buy some LED ones)

cheers


tim

[EtchedPixels]

For the LED ones it depends on the LED and you want at least the LED supplied with each CR signal etc. Adding extra resistors will make them dimmer but to be honest the CR signals ones are pretty much right, leaving aside the filters on read signals meaning you can't see the colour except at a very shallow angle.

Resistors don't drop volts so for bulb type lights I do it by trial and error adding extras to a 16v rated bulb, you can work it out but its all very non linear and ugly.

LEDs need to be current limited rather than just voltage limited, which means you need to know the current rating to find the right resistor, or simply use the supplied one and add more in series (adding more in series will dim the light). Again the supplier should be able to advise.

Because LEDs draw different amounts of power you want each LED wired with its supplied resistor (+ any others) not just one resistor the lot. If you do the latter it often doesn't give the results you might hope for (you'll get some very dim, some very bright)

[upnick]

Here is a thread i  just posted  for resistor  colours  & codes i  hope  helps

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=2356.0

[Corncrake]

LED lights need DC

Umm, well actually, LEDs are diodes and when reverse biased they draw little (negligible) current, when forward biased they draw considerable current, emit light, and need to be current limited either by the psu source resistance or an in-circuit extra resistance.
So, although the OP clarified the supply in use at this time, nevertheless the led can, if needed, act as its own (rectifier) diode when supplied with AC !

/pedantry

[bluedepot]

cheers for the info

this is all new to me so i understand very little of it! anyway i'm learning...


tim