[TriLUG] [OT]: Best RadioShack (or equivalent) in RDU

[John Riselvato]

Thanks John for the advice. I went to that store after work and to my
surprise you are correct, it does have the largest electronic component
section. I was able to get everything I needed.

I took Brian Hennings advice and went with a 9V clip instead of AA. They
actually didn't have a AA holder for two batteries. I also bought a huge
bag of resistors, last one in the store. Thanks again everyone who gave me
feed back!

Cheers,
John


On Mon, Feb 10, 2014 at 11:59 AM, Brian Henning <bhenning at pineinst.com>wrote:

> John Riselvato wrote:
>
> > I'm looking for low voltage blue LEDs, a two AA
> > battery holder/case, switch and resistors that would interface correctly
> > with the LEDs.
>
> John, I can't address RS's stock status, but I wanted to chime in for this
> reason:
>
> Be aware that most discrete through-hole blue LEDs have forward voltage
> drops nearing or over three volts (2.7V for 3mm, 3.2V for 5mm).  You might
> want to consider powering your project with a 9-volt battery instead of a
> pair of AAs (only ~2.4V if you use rechargables).
>
> (Skip the next part if you're already familiar with Ohm's law to find the
> appropriate resistor for a given LED)
>
> For a typical 3.2V blue 5mm LED with 20mA forward current and a 9-volt
> battery, you'll need a resistor as follows:
>
> 9V - 3.2V = 5.8V across the resistor
> 5.8V / 20mA = 290 ohms
>
> Hope this helps, and good luck!
> ~Brian
>
>
>
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