#31956 - mymateo - Thu Dec 16, 2004 7:26 am
Totally off topic, has nothing to do with games or game development, which is why we have this wonderful off-topic section!
My roommate wants to put LED's into his custom Dragon case for his computer (the "dragon" is a stainless-steel dragon head that fits over standard cases), but would like to have them on a powerbar, not hooked directly into his computer.
To the best of my caveman-like-primitive knowledge, it should be pretty easy. Just take a regular polarised plug from any defunct gadget laying round that you can cannibalize, hook it into a circuit board, and have LED's coming off of that. The problem is this: I don't know what to put on the board. Obviously, I'll need to regulate the amperage and voltage down to a point where I don't electocute myself or melt the LED's.
So if anyone knows enough on how to do this, and it's easy to explain, could you help? (Even if you just know of a website that can explain this, that's good enough!) Thanks!
#31957 - Krakken - Thu Dec 16, 2004 7:30 am
You'll want a transformer to bring down the voltage. I strongly recommend against doing this though. Power outlets give off an extremely strong current which could be very dangerous. What is the reason for him not wanting to be hooked up to his computer?
#31958 - tepples - Thu Dec 16, 2004 7:31 am
If you buy another PC power supply, you can plug anything into a standard power strip that you want, and it'd be just as safe as plugging it into the molex jacks inside the computer.
_________________
-- Where is he?
-- Who?
-- You know, the human.
-- I think he moved to Tilwick.
#31962 - mymateo - Thu Dec 16, 2004 7:49 am
Krakken:
To keep the dragon removable, as well as to be able to switch the LED's and the fan on it off via power bar.
tepples:
This thought occured, but (a) not enough viable room to keep an entire 2nd P/S, even a tiny one that comes in lower-end (there's a higher-end?) e-machine, and (b) he's hoping to keep the cost down. This is why I thought it might be possible to just do a little solder job with $3.50 in components to handle it.
But, from what you're both telling me, it's going to cost more than that to do the job. I guess maybe just summa those LED christmas lights would do the trick...
Thanks anyways! Appreciate the help
#31965 - Fatnickc - Thu Dec 16, 2004 8:09 am
Probably a bit late/not wanted, but I have an idea...
you could have batteries that are rechargeable so it is completely free...
EDIT: free as in free of wires to wall
#31971 - blinky465 - Thu Dec 16, 2004 10:14 am
I've done some work with microcontrollers and the like and quite a bit with LEDs from a DC supply.
It'll probably cost a little over $3.50, but you could get a 12v or 9v adaptor (choose one to suit your fan - find out how much power it consumes, divide the wattage by your voltage to get the total current draw for the fan. Now get an adaptor that can provide this level of current - the LEDs themselves will draw negligible current.) You're probably looking at milliamps so a really cheap supply will do.
Batteries would work a treat for the LEDs alone, but if you want to run a fan, you'll need to match the total voltage of the batteries to the voltage required for the fan (e.g if the fan runs from 9v dc, you could use a big square battery, if its 5v, you may have to make do with 3x1.5v AA batteries and see if that's enough to drive it).
Running the fan on batteries will mean lots of recharging for you!
However you do it, just provide a dc power source with a voltage that best matches your fan, and can provide just a little over the total current drawn by it.
The only thing to remember is to stick a fairly meaty resistor in series with your LEDs to stop them drawing too much current and melting.
You don't have to be to accurate here - a few kOhms should do; if the LEDs are a bit dim, reduce the resistance, if very bright, increase it a touch - you want your LEDs as bright as possible, but running at about 95% luminence.
Don't get hung up on the maths behind it either. Unless you're dealing with really delicate components (which you're not) the voltages and resistance values don't have to be exact, just within a sensible range!
(how do you find a sensible range? keep upping the voltage and reducing the resistance to your LEDs until something smokes....)
#31973 - blinky465 - Thu Dec 16, 2004 10:25 am
I'm not sure you level of understanding of electronics, so I apologise if the following is a little patronising. But here you go...
Power = Current x Voltage or Current = Power / Voltage or... you get the idea!
Provided you're giving your board the correct voltage, you only really need to regulate the current and to make sure that your power supply can supply the current "asked for" by the components.
e.g. if you have a 10W fan running on 5VDC, it will draw 2Amps. Just make sure your power supply can provide, say 2.5Amps (allow a little over for your LEDs, although their current draw is negligible)
If your power supply can provide a maximum of, say 4Amps, you'll need to put a resistor in series with the fan, to stop it drawing too much current (and causing damage to the fan motor). You should always put resistors in series with your LEDs - even with a supply of milliamps. Resistors in the region of 1k-10k should suffice - if they are dim, use a lower resistance.
On a very basic level, a resistor with a low melting point is a fuse (note how fuses are rated by the current required to make them blow) - most expensive components are protected by fuses rather than resistors, but shouldn't be necessary in your case!
#31990 - pyros - Thu Dec 16, 2004 7:43 pm
Just get a plug-in-transformer thingie with the right voltage....
lots of gadgets come with them, but you'll want to get one with a low voltage (2vish??). i.e. mobile phone chargers give off about 12v, also electronic keyboards often take about 12v-16v input.
In fact my gba plug says:
PRI: 230V (uk mains voltage)
SEC: 5.2V 320mA (output-to-the-gba)
You can (in the uk) buy one that has a switch on. You plug it in and can switch to say 3v,6v,9v,12v,16v,24v or something. some have an ac/dc switch as well i think.
They look a bit like this, but come cheaper, a few ?.
http://www.speedydelivery.co.uk/electrical-goods/240v-mains-adjustable-power-supply-3v-to-12v-variable.shtml
#31991 - pyros - Thu Dec 16, 2004 7:57 pm
also:
this gives very safe voltages/ampages.
if they are too high for your led's; i.e. it burns them out, then wire them in serial (or combinations of parallel serial arrangements) so that less power goes into each :)