Not really that much difference really, probably the second one as to no interferance from each other.
aha,...i asked because i was wondering if in option2 the voltage would create small capacities and if so, that capasity could damage the ccfl or something....
Well assuming it is in your computer off of a molex connector, just use seperate ground wires to be on the safe side. Both should really be fine, the LED wont suffer at all, they are resilliant buggers. The CCFL shouldn't have any detrimental effects to it. I would jsut go ahead with it, if you are worried, just use seperate grounds. As for capacitive effectI don't see any reason there would be any.
i wanna make a simple controller of two ccfls...and when i turn the ccfl on the led will get turned on too....so with one wsitch i must turn on both ccfl and led...is there any other way i can do that?
Sure there's other ways, but what you have drawn above will work just fine... Whether or not you have seprate ground wires or not doesn't really matter because ground is all connected inside the PSU and then into your wall plug anyways...
ofcourse there are other ways...what i wanted to say was if there is another as simple way as mine because i dont hav much tools and i cant suply with ICs if needed at least not straightforward cause i will be in my village for xmas vecations these days...
Actually, #2 seems a bit dodgy to me. Just goes against my better judgement without knowing exactly what current could flow through the ccfl if the ground switch is opened. Potentially, you've got 7V with the switch open (I've never been a fan of that 7V trick with switching psu's anyway), and that could be more than the reverse voltage rating of the led. Typical led's only have reverse voltage specs of around 5V. Personally, I'd choose option #1.
Or Option 2 with a double-pole switch moved to the high side to switch both 5V and 12V lives at once. But Option 1 might save a few pence and nothing wrong with it. Option 2 just looks wrong.
3.3k will be fine if the LED is to be used as an indicator lamp to tell you if the CCFL is on or not. If not (i.e. you actually want to illuminate something with greater effect), then try the calculator posted above.
no i dont want to illuminate anything! just indicator lamp. the problem was that i had no clue about forward amp and voltage of the leds im gonna use... but i connected one led with a 1khom resistor and supplied them with 5volts and the circuits amp was about 3mA and the leds volt was about 1,9 using those numbers as granted i calculated that i sould need aresistor about 3,3khoms so i suppose i was right?
On a 5V supply the 1k resistor would give about 3mA on 2V LEDS, 1.5mA on a 3.5V blue or white. That's plenty for an indicator. Running off 12V a 3k3 resistor will give the same 3mA on red/orange/yellow/green 2V LEDs and about 2.5mA on blue or white so still fine. Only use the spec currents when you're trying to light up a case or making a torch.
ok then! i have connected the leds with their 3,3k resistors and they wait to get modded in to a floppy bay...soon i will post all the worklog not only of making this contoller but the hole case....just wait! its not that great but i like it and its my first attempt on modding..... the mod will start if everything go well this weekend
