Keyboard mod help

[phalkon30]

I just bought some blue LED's, and was thinking about putting them under the keys in my keyboard, one on either side, just to give a little glow behind them.

Its a cheap Microsoft Internet Keyboard. I'm thinking about soldiering it onto the NumLock LED, but I'm wondering if 2 LED's would be too much power draw on that circut. Or, is there another circut that would be allways on, that could handle the current of 2 LED's? I'd rather not fry something.

I don't have specs on the LED's right now, as the site I bought them from is down for repairs. I'll have the LED's by friday I hope, and the site should be up before then.

From what I remember, they were 3.3v 4400MCD blue LED's.

[isus]

i have 2 led's, but i put them into the appropriate plugs from the ps2 port... use a multimeter.

they glow underneath my translucent volume keys. it's nice, but since i never soldered them onto the plugs, they have a tendency to blick on and off occasionally.

in conclusion:
just stick them right on the incoming power...

if you haven't opened up your keyboard yet:
it's basically a little circuit board, and a big pad, and a bunch of keys. the cable plugs into the circuit board, and the circuit board is attached to the big pad. the led's are on the circuit board.

at least, that's how it is on my logitech.

[phalkon30]

Thats exactly how it looks with mine. I have mine on the floor in pieces right now, my cousin dumped a full glass of water on the keyboard, while it was ON.

So...if it still works...

There are a few great soldier points right where it plugs into the board, I just need to know which ones to use.

Black, white, brown, red, big black. Thats the order of the wires from left to right. Sound similar?

[wonderboy2005]

instead of basing your procedure on the that of somone else's (different) keyboard, it'd probably be best if you tested for the correct wires. if you get the setup wrong, at best youll have to reconfigure them. at worst, you'll short out the whole KB and your out probably $50.

with LEDs you do not want to pump a higher voltage through than they were designed for. you'll ruin them right away. so make sure the source of the power to the LEDs is the same as they are rated for.

though i cannot say for sure, i doubt you would have any problems just piggy-backing the new LEDs on the existing LED circuit(s). LEDs take very little power. ive seen mods where there is atleast one LED under every key. it looks pretty cool.

now i have a question for you guys: is it possible to use a mac usb keyboard on a PC? i would love to take one of the newest apple KBs (with the white keys) and put blue LEDs under every key and use it on my PC. also, if i could do this, could i reassign keys? i remember when i was a mac person that the 'help' key always bugged the hell out of me, because i would push it when trying to hit the delete key. now that i am more familiar with the KB, this is not very likely to happen, but still i dont want a help button on a KB.

[phalkon30]

At LAN partys a friend of mine uses a mac USB keyboard all the time. With both that and a PS2 keyboard plugged in, he can type on both at the same time.

I suppose you're right about testing it for myself, I'm just kinda lazy and anxious to get it done :)

[phalkon30]

http://www.case-mod.com/store/product_info.php?cPath=26_60&products_id=383

Thats the LED. 3.3v, I really wonder if thats going to be too much draw on the keyboard.

[isus]

nah, led's aren't that 'heavy'. i think usb can handle 500mA.

but you definitely need to take a multimeter and find which points to solder the led's onto. and make sure you don't get them backwards... i did that on my first try (i didn't have the fresh-bought led's with one tail being longer than the other) and i had to resolder. so just pay attention and use common sense, and you'll be fine.

[phalkon30]

Its not a USB keyboard, its PS2, which is why I'm wondering, but you're probably right, 20ma isn't that much of a load.

[isus]

ooo... well in that case, it's no load at all... my k/b is ps2, and i don't think ms vs logitech would have that much more to power in a keyboard.

[wonderboy2005]

yeah... the amperage will not be a problem. you just have to worry about the voltage being too high... im not sure what the voltage is for most KBs so youll have to check that.

[zaphodiv]

Putting an led in parallel with another is likly to result in both led's glowing less brightly. It probably won't cause any damage.

AT and PS2 keyboards have a 5volt supply from the computer.
pinout here (http://www.physiol.ox.ac.uk/~trp/pinouts.html), as Isus says, you need a multimeter to do this properly.

To drive a 3.3v 20ma led from a 5volt supply you can put a 100ohm resistor in series with it. Use a higher value resistor if it's too bright.
Most LED's are about 2.2 volt so a 270ohm resistor will let it light up brightly on a 5volt supply.

Shorting out the 5volt supply to the keyboard is a bad thing. Most motherboards have a self-reseting polyfuse to limit the current however I once had to use a soldering iron to replace the keyboard supply fuse on a poor quality motherboard.