# of LEDs off of a Keywhiz Eco

[NoBonus]

I want to run one or more LEDs off of the 5v output on my KeyWhiz Eco, however, I am not sure how many the 5v output could push in parallel without causing any problems.  Any ideas?  I am leaning towards using 3.6v white or blue LEDs(with appropriate resistors), but how many will I need to successfully light my blue translucent trackball and not burn anything up?


Thanks

[Buddabing]

Here's an informative page.

I have read that you should not pull more than 100 mA through a keyboard port. If each LED draws 15-20 mA, three or four LEDs should be safe enough.

You should ask Randy.

[NoBonus]

I see a lot of talk about the negatives of using LEDs in parallel withonly one resistor, but recommendations about parallel with one resistor per LED.  Unfortunaly, I see no info on hooking up LEDs in parallel with individual resistors.  Do you know where I can find this info?

[NoBonus]

I also noticed that at lsdiodes, I can get a 5mm Blue THC3 11000mcd LED that uses 80 to 100 mA or I can get 3 or 4 5mm Blue - 5900mcd LEDs that use 20 to 30 mA...  which is the better pick?  Am I better off with a single, brighter light or a few dimmer lights to light a translucent blue trackball?

[NoBonus]

Also, do I run the LEDs at "TYP" or "MAX"?  Will "MAX" fry them?

[cholin]

At LSDIODES, there should be a little small tutorial about hooking up LEDs in series, parallel, etc.  Trackball lighting is choice, and I dont have one so I cant help you.  Im guessing 2 would do the job.  Running the LEDs at TYP would be the efficient way to do it.  MAX is how much the LED can stand before it blows up on you   (That means use TYP)

[NoBonus]

Thanks!

So what do you think? A single, really powerful LED or a few less powerful LEDs?

[cholin]

The best one Ive heard of was someone that bought a cheapo flashlight and just used the bulb.  I know they give off heat and all that, but a bulb at 3 volts doesnt do too much damage.  Use the reflector and theres concentrated light   I say go for 1 well placed one or two lower ones.  You need to check the viewing angles and crap though, so come to think of it, just go for two, what have you got to lose, a few cents?

[Chris]

The best one Ive heard of was someone that bought a cheapo flashlight and just used the bulb.

[NoBonus]

Thanks for the info!!

[cholin]

I didnt mean running it off the keywiz, sorry, didnt think about the origional topic.