NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Heath Hezzanith question
From: Greg R_
Date: 2007 Oct 22, 21:38 -0700
From: Greg R_
Date: 2007 Oct 22, 21:38 -0700
--- Chuck Taylorwrote: > 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 > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---