Electronics simple LED question - parallel or series

hello

I want to wire up 3 LEDs onto the HDD activity header on my mobo. Should I put them in parallel or series in order to keep them all bright?

Sorry for being simple but i've never been taught this stuff + I probably could find out but im busy installing windows at the moment and could do with a timesaver...

cheers

chris

 

Parallel, but it might not be a good idea to wire 3 LEDs to your mobo header as it may draw too much current through it and damage your motherboard.

You've got 2 options to overcome this, Zap's re-wired HDD activity LEDs guide (in the mod guides section) or to use an optoisolator (as in linear's IC guide).

 

As 'crimmie said, you'll need something like an optoisolator (see macro's circuit - http://www.bit-tech.net/article/83/) because you won't get 60~75mA from a hdd header I don't think (though it should current limit and not hurt anything if you try).

Rob.

 

Thanks guys. was hoping for a one word answer really that circuit looks a little bit too much for someone who has to ask "series or parallel" lol but thanks for the help

i might try using plexi sheet to reflect the light to get the same effect.

BUT... If i was to put them in series would they draw the same current as one LED but not as bright?

cheers

 

series really isn't an option.

I don't think Cheese meant the whole circuit just the opto-isolator part in the bottom left, linear drew a picture:

bandwith theft, i know
Full article here: http://forums.bit-tech.net/showthread.php?s=&threadid=8965

Have you looked at Zap's guide? Thats easy to follow:
http://forums.bit-tech.net/showthread.php?s=&threadid=23567

 

thanks acrim.. i should be able to handle that one
I'll try and pick one up.

cheers

 

Just a quick explanation as to why series is a bad idea:

Most mobo LED headers only give off 3v (although more boards, mine included, have LED headers that give off 5v). At 3v, you'd need LEDs that operate really close to 2v, the closer the better, as your standard 3.7v superbrights have no chance of lighting up at only 1.5v, while a 2v LED might (this is called the forward breakover voltage, a diode has a minimum forward voltage and a maximum reverse voltage needed to conduct). Plus, 2v LEDs are quite wimpy, and it sounds like you're using LEDs to illuminate mostly, which would make them a poor choice.