TNT Newsletter for February 6, 2007

Throw away your calculator (but not your computer), save your eyes, keep up to date on the stars, make super-quick breakfasts, and have a rockin' good time making a literary clock.

Arwen O'Reilly
Staff Editor, Make Magazine
Makezine.com
toolbox@makezine.com

The Maker's Edition Pocket Ref: No Maker's Tool Kit Should Be Without One!

This great little book is a concise all-purpose reference featuring hundreds of tables, maps, formulas, constants & conversions and it still fits in your shirt pocket! Packed with mathematical formula, tables, standard conversion ratio, electric wire size vs. load, resistor color codes, Morse code, sun & planet data, earthquake scales, nail sizes, geometry formulas, currency exchange rates, and much more! It's no wonder The Pocket Ref was featured on MythBusters.

And now, with each two-year subscription to MAKE magazine, you'll receive your own MAKE Special Edition Pocket Ref as our gift to you. And if you already subscribe, we'll extend the same offer on any two-year renewal.

Subscribe today!

Reviewed by Bob

One of the most useful tools I've found for Makers is Google's built-in calculator. It knows about all kinds of units and is as simple as typing in plain English.

For example...

Say I have an LED that I want to run from a 12V DC power supply. I already know that the LED requires a forward voltage of 2V and and a forward current of 20 milliamps. What I want to know is how big my current limiting resistor needs to be.

I know I need to drop the voltage by 10 volts, and my draw will be 20 milliamps, so I go to the Google search page and type "10 volts / 20 milliamps" in the search box, hit enter, and out pops my answer... "(10 volts) / (20 milliamperes) = 500 ohms." Woohoo! Now, I've never seen a 500-ohm resistor, so I opt to use a 470-ohm, which is pretty close.

Next I want to build an enclosure for my little project, but I only have measurements in inches, and I want millimeters (because I'm an engineer). This time I type "9 in in mm" and get "9 in = 228.6 millimeters." Great!

To celebrate my project, I decide to bake a cake, but I don't have the correct measuring jug. The recipe says 2 cups, but I can only measure in fluid ounces. No problem, Google calculator has me covered! I type in "2 cups in fl oz" and get my answer "2 US cups = 16 US fluid ounces." Doh! Of course it is, but I'm curious to know what that is in gallons. Now we type "2 cups in gal," and get "2 US cups = 0.125 US gallons."

Now I'm obsessed with gallons and have some time while my cake is baking. I decide to find out how economical my truck is. I know a full tank is about 15 gallons, and I can do about 225 miles before I need to refill. I head over to Google and type "225 miles / 15 gallons," and I'm surprised by the result "(225 miles) / (15 US gallons) = 6.37715558 kilometers per liter." What kind of measurement is that? Never mind. I can specify the units I want the results in. I retry with "225 miles / 15 gallons in mpg" and get "(225 miles) / (15 US gallons) = 15 miles per gallon." Ouch! Hmm, I need a new truck!

Maybe it looks better in different units ... time to try something wacky! This time I tried "225 miles / 15 gallons in mm per fl oz" and got my result: "(225 miles) / (15 US gallons) = 188 595 mm per fl oz." Looks much more impressive now :)

Also, Google calculator does currency conversions: "99 gbp in usd," gives "99 British pounds = 195.2676 U.S. dollars."

You can even do clever stuff like working out what people in the UK pay for gas in your local currency and measurements...
"0.89 gbp per liter in usd per gallon" gives us
"0.89 (British pounds per liter) = 6.64504815 U.S. dollars per US gallon."
Ouch! \$6.64 a gallon is a rip off!

Discussion

Magnifying Ruler

http://www.amazon.com/ACM40719-Westcott-Processing-Magnifying-Ruler/dp/B00094CR7Q
\$2

Sometimes the most useful tools are also the most low-tech. Growing up, I always remember my dad (a dental school professor) having one of these and using it to save his eyesight when digging through reference books with tiny fonts. As an editor, I found myself squinting to figure out if that quotation mark is a "straight quote" or a "curly quote" and straining to determine whether there's an extra space in the text or if it's just my eyes playing tricks on me. I was so excited to rediscover this magnifying ruler. With it's bold blue lines surrounding the magnified strip, my squinting days are over. We love it so much that we ordered one for each of our editors. Truly the best two bucks I've spent in a long time!

Discussion

Easy 40-Second Egg

Reviewed by Arwen O'Reilly Griffith
http://www.instructables.com/id/EX971HRLE0ETVPM6OD/

Short on time? Well, you can make yourself a poached egg, if only you have a microwave and an egg (and 40 seconds). Check out Hoopajoo's great Instructable, and never skip breakfast for lack of time again!

Discussion

Sky Calendar

Reviewed by terrie
http://www.pa.msu.edu/abrams/SkyCalendar/Index.html
\$11

Sky Calendar comes as a one-page per month subscription from Abrams Planetarium at Michigan State University. The front of the page is a calendar that's packed with information about planets, moon phases, and other sky events during the month. The back of the page has a map showing major constellations and planet locations during the evening through the month.

When you subscribe, you get three months of Sky Calendar at a time. It's been around for years and continues to be a great resource for casual sky watchers and amateur astronomers alike.

Discussion

Literary Clock Instructable

Reviewed by Arwen O'Reilly Griffith
http://www.instructables.com/id/EZTUO52E98EVYE0J1T/

As much as I hate seeing books butchered, I have to admit that this seems to be a good use of your time. (Arrggh! Pardon the pun!) Instructables user mdhaworth has a great how-to on making a simple clock with a book cover as its face (after all, children's books and cookbooks do seem to take the most heat, and you might as well do something clever with the remains).

Discussion