# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Heath Hezzanith question
From: Greg R_
Date: 2007 Oct 22, 21:41 -0700

```--- "Greg R."  wrote:

> a current of 20 mA (0.2 A)

Oops, dropped a zero from the previous post - that should obviously be
0.02 A, not 0.2.

--
GregR

> --- Chuck Taylor  wrote:
>
> > Bonus question:  What size resistor would I need?
>
> Bonus answer: It's a simple voltage divider/Ohm's Law problem. You'll
> be dropping 1.3 V across the resistor (3.0 - 1.7), and a current of
> 20 mA (0.2 A) through the series circuit gives a resistance of 65
ohms
> if I did the math right.
>
> --
> GregR
>
>
>
> > Why not use an LED?  Radio Shack sells a 5 mm red LED for \$1.99. It
> > draws 20 ma at 1.7 volts (typical).  My sextant takes two penlight
> > batteries (3 volts). To make this work without smoking the LED, I
> > would need to solder in a resistor of the proper value in order to
> > drop the voltage to 1.7 volts. But first I would have to do the
> math
> > to compute the proper value for the resistor. I think I'll stick
> with
> > the red marker. :-)
> >
> > Bonus question:  What size resistor would I need?
> >
> > Cheers,
> > Chuck Taylor
> >   48 N
> > 122 W
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Gary LaPook writes:
> >
> >
> >
> > Why not use this opportunity to join the 21st century and use a red
> > LED
> > (light emitting diode) cheap at Radio Shack, uses almost no current
> > and
> > lasts forever?
> >
> >
> >
> > gl
> >
> >
> >
> >
> >
> > Chuck Taylor wrote:
> >
> >
> >     red nail polish on the bulb or lens.
> >
> >
> >
> > I use a red felt-tip marker for coloring the bulb on my boat's
> > compass. It works well. It would likely work also on a sextant
> light.
> >  I picked up that trick from a compass repairman at a boat show.
> >
> > Chuck Taylor
> >   48 N
> > 122 W
> >
> >
> >
> >
> >
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam?  Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com
> > >
> >
>
>
> >
>

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