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August 15, 2005, 6:44 am
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Its been a long time since i've done much electronics work .. just need
to re-check some things .. Hooking up some extra leds to a PC case, running
from the +5v line. The current setup is 1x "Bright Blue LED, specs unknown"
running direct from +5v, no resistors, nothing .. What i'm planning on doing
is putting 5 LEDs in its place (Jaycar Part Number ZD0182).. Which is the
best way to wire these? Will 5 of them run ok from +5?
Also, planning on replacing a HDD light (normal 3mm red led) with a Bright
Red 5mm LED, (Jaycar Part Number: ZD0156) .. Is there any issues foreseeable
connecting one of these directly to the motherboard? Would its power draw be
much higher than a standard 3mm LED, in terms of affecting/damaging the
motherboard? I'm guessing not, but just need to double check :)
Thanks in advance for any info/help!
Re: 5x LEDs
You need 1 resisor in series with each LED, The value of which is
(5V-3.2V)/20mA90%ohms, use say an 82ohm as the LED is rated at 30mA
Are you sure the old LED is being powered directly from the +5V rail?,
have you checked the votage across it while it's on?
If the +5V wire is directly connected to the +5V power supply rail then
it will be able to supply the current you need.
Nope, they both drop the same voltage (different colours have different
voltage drops), so the current will be the same.
Re: 5x LEDs
Thanks for the calculations, i thought i'd need somthing :)
And my bad about the old one .. cut away the heatshrink up its legs, and
there is a TINY resistor soldered directly to the leg of the LED :)
I'll drop by DSE tomorrow and get some bits, then i'll be set :)
Eeexcellent :) Dunno what was in the minds of the makers of this case to not
put a hdd light on the outside of the door :)