OK, first thing's first:
Me + electronics knowhow =

I found this guide yesterday on using an optocoupler/optoisolator to separate the motherboard signal from your LED's: linky

Instead of running scared from those big words, I put on my reading shoes and had a decent look through.
The optocoupler basically is an infra-red emitter and receiver on separate sides of a chip - the motherboard signal gets transmitted optically frome one side to the receiver, which picks it up and acts as a switch on the other side (for a separate circuit running your LED's)
Essentially, what this means is that you can use the motherboard pin header, but power as many LED's (or anything else for that matter! )as you want DIRECTLY from the PSU without risk of frying your mobo!!

The part that REALLY got me stoked is that these chips are CHEAP! I bought mine for just under $2NZ (forgoing my can of drink for the day)


On my current case I had 2 HDD LED's connected to the HDD header on the mobo in parallel. They were SO much weaker than the power and msg. leds, Using this idea, I hooked 3 led's up to a 4N25 optocoupler and 12 volts while joining the mobo pins to the other side (that's right! even I could do it!!! Just remember, the recessed dot on the chip is above pin 1)

Sure, this ian't NEARLY as cool as a dragonmodz array, but there's SO many things that you could do with it:

LED lighting your whole case so it flashes when your HDD get's accessed? power EL wire to flash - (would be sweet for those EL HDD cables)? fancy custom built LED power switches

I think i'm going to use this on my refurb project somehow....

whadda ya think?

Cool. I found a 4N25 (cf the recommended 4N27) at Maplin (UK) ... don't know the signficance of the 27/25 but it sounds about the same. I'll bear it in mind for the future.

Yeap you got it right Masterp. Opotoisolators "ISOLATE" a Signal, hence the name Opto (meaning Light), ISOLATE (meaning to move away from).

These chips in the US run for abotu 50cents or so..There are other types and have more current capablitys or are made for higher voltages.

Heres something you dont know, you can find these in SOME switching powersupplies.

These things also prevent "loading" on the signal line, meaning you keep both of them isolated, but are mirrored (so one signal is on one side, and you see the same signal on the other side). They also keep the orignal signal clean from loading.

Quote: Originally Posted by username#132 Cool. I found a 4N25 (cf the recommended 4N27) at Maplin (UK) ... don't know the signficance of the 27/25 but it sounds about the same. I'll bear it in mind for the future.

Those are part numbers. Different models may have different voltage, or current capablitys. Check the schematic also to see its physcially the same. Some models may eveb have LESS of those abilitys than the ones you are supposed to have.

woa this is interesting


btw where in US can we get the chip? does radioshack have it?