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How many GGG LEDs can I wire together when connected to the PC's 5V power?
unclet:
I would like to wire some of Randy's LED lights directly to my PC's 5V/ground power supply connectors. How many of these GGG LED lights can I wire together and still have them work?
(EDIT)
All LED lights will be wired in parallel ....
Franco B:
Depends on the LED forward voltage, the LED forward current and how you wire them
I think you will get more if you wire the LEDs in parallel.
This is a handy link that will work out an array for you and also tell you what resistors to use.
http://led.linear1.org/led.wiz
Put the values of the resistor in and then just keep increasing the resistor count until you cannot add any more.
unclet:
That link you provided me is way over my head. Pretend I have absolutely no knowledge of electricity. :)
Now, I am using the resistors which Randy includes with the GGG LED lights and I am wiring them in parallel.
Perhaps someone can tell me how many can be connected together using one set of 5V/ground lines from the PC.
Neverending Project:
I was in the middle of writing a reply when Franco B beat me to it. ;)
Another thing to consider is the USB bus itself. The USB bus allocates current in 100mA units, up to 500mA per port. Most places you plug your USB cable into in your PC will actually be a hub (even the front USB access in your PC is usually an intenral hub), and hence will most likely only be able to pull between 100mA and 500mA. If you plug your USB cable into a self-powered hub, it may depend on the total current rating of the hub itself.
Unfortunately, it will be a bit of a trial and error for you. Each USB device will be different, and other devices on the same bus will be drawing current also. As a general starting point, I calculated that you should be able to get 5 LEDS in parallel with a 100Ohm resistor each, and this will draw about 100mA.
FWIW, if you are talking about the ButtonBlaster LEDs from GGG, according to his site they have a drop of 3.0-3.5V (most LEDs like this are around 3.3V) and draw 20mA current each.
Hope this helps.
[EDIT] Hold on a minute here... I somehow thought you wanted to connect them to the 5V in a USB bus, but now I realize that you are talking about the 5V power supply. In this case, it depends on how much current your power supply can dish out (taking into account the rest of the 5V circuitry on your computer that also needs that current). Sorry for the mis-info above.
RetroACTIVE:
--- Quote from: unclet on January 31, 2008, 04:38:47 pm ---That link you provided me is way over my head. Pretend I have absolutely no knowledge of electricity. :)
Now, I am using the resistors which Randy includes with the GGG LED lights and I am wiring them in parallel.
Perhaps someone can tell me how many can be connected together using one set of 5V/ground lines from the PC.
--- End quote ---
(current) X (voltage) = power ... example: 20mA over 5 volts = 0.1 Watt per led
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