Right this might have been asked before But I can't see anything about so I'm going to ask it now! I want to put a pair of cold cathodes into my keyboard but I don't want to mod the wiring really. I mean ok so they should run on 12volts but what will happen if I were to try to run them off of 5volts, would they just be dimmer? (not really a bad thing) or would it do damage to the inverter/keyboard power/tubes? thanks --=] J [=--
I don't know about undervolting a CCFL, never tried that with mine. but the best thing might be to simply get an inverter that runs off 5 volts. check Here to see what I mean. dunno if you could get them there, but i'm sure you could find something similar. that's my opinion anyway.
The 1st CCFL I ever bought came with a 5v inverter. Just look around, you're bound to find something.
hmm thing is that cc s are really cheap on ebuyer atm... would be a shame to have to buy another inverter... would be nice to see a dual output 5v cc inverter too. --=] J [=--
as far as i remember the whole tube doesnt light up it only lights half of the tube if you undervolt them
i had a CC on a baybus (ie on a dimmer) once. starting at no volts: it would light up dim at one end, then move up to light the whole thing, then the whole thing would get brighter. so you may have to see at what voltage the whole thing is lit in your case. doesn't seem to have done any damage either - still going strong.
I think I have a cunning plan On ebuyer there are "led bars" .. specifically some that are USB powered... So .. I will get one of them... cannabalise the box on the end and solder it right to the keyboard controller board should work a treat... and they do 7 colour ones too! --=] J [=--
Even if you were to find an inverter that takes in 5v and delivers the appropriate AC voltage and current, or an inverter that undervolts them and you like the effect, you're going to have a problem in how much current your keyboard interface can supply. Consider this: I have an LCD that uses CCFL backlighting. I got an inverter for it that runs at 5v, and for these little tubes (less than 4"), the inverter draws more than half an amp. The longer the tube, the greater the power draw. The greater the power draw on the AC side of the inverter, the even greater draw on the DC side. And if you want two, then your current draw doubles. Here's some math to backup my statement. Assume for the moment that the inverter is 100% efficient (which there's no way in hell it will ever be because current will be drawn by the components necessary to generate an AC wave before it's transformed). If a single 12v 12" CC inverter draws .4A (4.8w), and spits out 1000v AC, then the current draw of the tube is 12*.4/1000 = 4.8mA (4.8w). If you were to get your hands on an inverter that ran at 5v, but spit out 1000v AC @ 4.8mA, then the current draw would be .96A. Best case scenario is that you have a USB, in which case the most current you could draw is .5A, which is still way below what you need to appropriately run them. So your choices are simple: either an external adapter or no keyboard CCFLs. edit: didn't read jazzy's last post. Lightbars are a good idea, although you need to look at the current consumption. PS/2 keyboards should draw more than 100mA, while USB keyboards shouldn't draw more than 500mA, and that's if they're plugged into either a hub with an external power supply or ports on the back of your computer. And since the USB chipset doesn't know you're drawing the extra power [apparently the USB controller has to send its current draw to the system so that the O/S knows not to use the device if it's plugged into the wrong port], you risk blowing something up).
I have a multimeter.. and will be using it! Thing is I was trying to find a way to use ccs instead of leds... I'm running 4 blue leds off my KB at the moment anyway, I don't think that the led bars are going to be too much of a problem, but what I will do is run them off a usb port and see what they draw before I transplant them to the kb. I mean the worst that could happen is that they draw too much and I have to use them inside the case instead! Cheers for the info. --=] J [=--
