L.E.D. Resistors

[POPEYE]

Just a thought but when and if a resistor breaks down/blows or whatever they do which way do they go? let more volts through or cut off volts alltogether, (or either way)? thinking if i'm useing one resistor on lots of led in parallel and it goes it may blow all of em or just cut the power (which is ok, as it'll be easy to replace one resistor)

[BUSHWHACKER]

They cut the power Ian.

[roylittle0]

They are basically a heating element, they just burn out and sometimes break in half, never known one short out yet.

[POPEYE]

Thanks guys, the thought just occured to me and wanted to check, at least if it goes it wont bugga up a load of leds

[MattF]

Yeah, as mentioned, absolutely no worries about it shorting. If you used a highly over-rated resistor, (wattage wise), then the chances of it going high resistance or O/C are practically nonexistent unless you are really unlucky. Using a metal film rather than carbon is also preferable. Don't forget to pop a fuse inline either.

[POPEYE]

Yeah, as mentioned, absolutely no worries about it shorting. If you used a highly over-rated resistor, (wattage wise), then the chances of it going high resistance or O/C are practically nonexistent unless you are really unlucky. Using a metal film rather than carbon is also preferable. Don't forget to pop a fuse inline either.

Cheer's matt

[SoundsDigital]

I cannot explain why, but when I have connected a bank of LEDs to one common resistor, they never seem to give off equal amounts of light. Would 12 volt LEDs be more suitable?

[MattF]

I cannot explain why, but when I have connected a bank of LEDs to one common resistor, they never seem to give off equal amounts of light. Would 12 volt LEDs be more suitable?

You are compensating|allowing for voltage drop in your design? Is the unequal brightness erratic in placement or otherwise? Are the L.E.D's from the same batch, i.e: all bought at the same time?

[roylittle0]

I cannot explain why, but when I have connected a bank of LEDs to one common resistor, they never seem to give off equal amounts of light. Would 12 volt LEDs be more suitable?

It’s a bit of an unwritten rule but you should (if at all possible) never connect more that three led's in series with one resistor

If you check out most of the led resistor calculators on the internet, they generally only show calculations for the max of 3 led's. and should thus be installed in banks of 3

[POPEYE]

What about "in paralell" is it ok to wire as many as you like on one resistor ? and they will all be bought from the same place at the same time, or is it best to do em in banks as well

[MattF]

It’s a bit of an unwritten rule but you should (if at all possible) never connect more that three led's in series with one resistor

It doesn't make a monkeys difference in practice if your design is okay.

[MattF]

What about "in paralell" is it ok to wire as many as you like on one resistor ? and they will all be bought from the same place at the same time, or is it best to do em in banks as well

How many L.E.D's are you fitting? Generally, a single bank is fine. Only reason to make multiple clusters is as a failsafe, i.e: you retain most segments if one goes down, which, come to think of it, may be the preferable way to do it for a brake light. Make sure you get 1% tolerance resistors, however, to keep everything as close as possible.

[POPEYE]

How many L.E.D's are you fitting? Generally, a single bank is fine. Only reason to make multiple clusters is as a failsafe, i.e: you retain most segments if one goes down, which, come to think of it, may be the preferable way to do it for a brake light. Make sure you get 1% tolerance resistors, however, to keep everything as close as possible.

About 300-400 i hope, all depends on finding/making the encloseure for em, plus if i can i'm gonna build in a rude message in em, switchable of course,

[BUSHWHACKER]

About 300-400 i hope, all depends on finding/making the encloseure for em, plus if i can i'm gonna build in a rude message in em, switchable of course,

Blimey!

Not only have you cleared the shelves of red Hammerite, but LEDs and solder too!