OK, my recollection from a web site about LED use said to figure a
voltage drop of 3.4 volts for the white ultrabrights leaving about a 9
volt drop for the resistor. At 600 ohms, this gives about .015 amp
through each resistor and LED. Yes, the correct resistor wattage is
less than 1/4 watt but I hate blowing resistorswhen odd things happen
and space saving is not a consideration here. Radio Shack had nothing
even as alrge as 1/4 watt less than 1000 ohms.

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OK, my recollection from a web site about LED use said to figure a
voltage drop of 3.4 volts for the white ultrabrights leaving about a 9
volt drop for the resistor. At 600 ohms, this gives about .015 amp
through each resistor and LED. Yes, the correct resistor wattage is
less than 1/4 watt but I hate blowing resistorswhen odd things happen
and space saving is not a consideration here. Radio Shack had nothing
even as alrge as 1/4 watt less than 1000 ohms.

That's what I really dislike about the "new" Radio Shack. I suspect once
their inventory of discrete components are gone, you won't be able to buy
*any* resistors, capacitors or anything there.

Eisboch

wrote:
OK, my recollection from a web site about LED use said to figure a
voltage drop of 3.4 volts for the white ultrabrights leaving about a 9
volt drop for the resistor. At 600 ohms, this gives about .015 amp
through each resistor and LED. Yes, the correct resistor wattage is
less than 1/4 watt but I hate blowing resistorswhen odd things happen
and space saving is not a consideration here. Radio Shack had nothing
even as alrge as 1/4 watt less than 1000 ohms.


It'd be more efficient to put 2 or 3 LED's in series with one resistor
so more of the power goes to lumens rather than heating resistors.

-rick-