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What's All This Homepage Stuff, Anyhow? THE BEST OF BOB PEASE What's All This Homepage Stuff, Anyhow? Once upon a time I couldn't even spell "Web Freak", and now I am one. But several people agreed, that in response to the popular demand, RAP should put out a "Web Page" with several kinds of useful information on it. You guys all know that there is an awful lot of garbage on the Great World Wide Web. I am trying to NOT contribute to that. I'll put on ONE set of information for people who have not been receiving Electronic Design: Some of my RECENT COLUMNS. Already we have over twenty, and I'll try to keep adding more. These will mostly be in straight ASCII, with no hokey graphics. If there are small drawings, we'll expand them to make them legible when you print them out. ● Remembering Bob Pease Topic: Driving High-Power LEDs Topic: Driving High-Power LEDs Without Getting Burned - Part 2 Without Getting Burned - Part 1 Your Hosts: Bob Pease & Dr. Howard Johnson Your Hosts: Bob Pease & Dr. Howard Johnson Guests: Patrick Durand - Future Lighting Guests: Patrick Durand - Future Lighting Solutions Solution Pat Goodman - Philips Lumileds Pat Goodman - Philips Lumileds Lighting Co. Lighting Co. Chris Richardson - National Chris Richardson - National http://www.national.com/rap/ (1 of 3) [3/23/2012 11:52:36 AM] What's All This Homepage Stuff, Anyhow? Circuit to provide rail-to-rail output, even with a (light) load Complete Circuit for Cold Toe Detector... Solutions to March 31 Electronic Design Puzzles The origin of the WOM - the "Write Only Memory" As decribed in my December 8 2004 ED column, "What's all this Merit Badge Stuff Anyhow", here is RAP's Merit Badge Workbook. Vacuum-tubes Op-Amps! View Our Archived Online Seminars ● The Use, Mis-use, and Abuse of Amplifiers (12/5/02) NoiseMaker and Level-Shifter and Preamp Circuits, to use with "Ripple-Rejection Stuff"! The San Francisco Chronicle had a good write up on Analog Designers Trekking in the Annapurna Sanctuary. Hikers and adventurers may enjoy reading about my trek around the Annapurna Circuit, in Nepal, in November of 1997. http://www.national.com/rap/ (2 of 3) [3/23/2012 11:52:36 AM] What's All This Homepage Stuff, Anyhow? Also, we'll try to have some Miscellaneous stuff: ● Anybody who has to do some REAL Analog Troubleshooting, and wants to buy my books, we'll make it easy. Just click on BOOK. ● Check here for a listing of ED columns ● If you want to see a horrible photograph, we may occasionally have one. Click on HORRIBLE. ● We will refer you to the Electronic Design Website. Just click on ELECTRONIC DESIGN. ● We will have LISTS. ● And if you have any comments on what ought to be in this Website, holler. Holler to [email protected]. Send nasty comments. I'll read your comments. ● AND we will also put in some good technical material, even for guys who have read all my columns in E. D. These will be based on some of the old technical notes I have written over the last 35 years. With comments. I bet you'll find something interesting. All for now. Best regards./ R. A. Pease / Engineer / NSC Site Map | About "Cookies" | National is ISO/TS16949 Certified | Privacy/Security Statement | Contact Us/Feedback | RSS Feed | Site Terms & Conditions of Use Copyright © 2011 National Semiconductor Corporation http://www.national.com/rap/ (3 of 3) [3/23/2012 11:52:36 AM] The Best of Bob Pease THE BEST OF BOB PEASE ● What's All This Neatness Stuff, Anyhow? ● What's All This Applications Engineering Stuff, Anyhow? ● What's All This Splicing Stuff, Anyhow? ● What's All This Muntzing Stuff, Anyhow? ● What's All This Teflon Stuff, Anyhow? ● What's All This Ground Noise Stuff, Anyhow? ● What's All This Femtoampere Stuff, Anyhow? ● What's All This Quality Stuff, Anyhow? ● What's All This Cost-Accounting Stuff, Anyhow? ● What's All This Smog Stuff, Anyhow ● What's All This Mentoring Stuff, Anyhow? ● What's All This Measurement Stuff, Anyhow? ● What's All This "SMWISICDSI" Stuff, Anyhow? ● What's All This Common-Centroid Stuff, Anyhow? ● What's All This Multiplication Stuff, Anyhow? ● How To Make Your Own Matched Transistors ● What's All This Box Stuff, Anyhow? ● What's All This VBE Stuff, Anyhow? ● What's All This Copper-Clad Stuff, Anyhow? ● What's All This Widlar Stuff, Anyhow? ● What's All This Reflex Response Stuff, Anyhow? ● What's All This Fuzzy Logic Stuff, Anyhow? (Part II) ● What's All This Dead Car Stuff, Anyhow? Site Map | About "Cookies" | National is ISO/TS16949 Certified | Privacy/Security Statement | Contact Us/Feedback | RSS Feed | Site Terms & Conditions of Use Copyright © 2011 National Semiconductor Corporation http://www.national.com/rap/Story/Index/0,1563,0,00.html [3/23/2012 11:52:42 AM] http://www.national.com/rap/images/circuit120507.jpg http://www.national.com/rap/images/circuit120507.jpg [3/23/2012 11:52:43 AM] Complete Circuit for Cold Toe Detector... THE BEST OF BOB PEASE Complete Circuit for Cold Toe Detector... Link to Electronic Design Article http://www.national.com/rap/coldtoes.html (1 of 2) [3/23/2012 11:52:50 AM] Complete Circuit for Cold Toe Detector... Site Map | About "Cookies" | National is ISO/TS16949 Certified | Privacy/Security Statement | Contact Us/Feedback | RSS Feed | Site Terms & Conditions of Use Copyright © 2011 National Semiconductor Corporation http://www.national.com/rap/coldtoes.html (2 of 2) [3/23/2012 11:52:50 AM] Solutions to Mental Math Puzzles, Electronic Design, 31 March 2006 THE BEST OF BOB PEASE Solutions to Mental Math Puzzles, Electronic Design, 31 March 2006 1. How can a train ascend a 1-mile radius hemisphere, without exceeding a 4% grade? The train track must spiral up the hill as far as it can, at a 4% gradient. About 25 miles or so, up to point "X". And how far is that, exactly? Where is this "point X"? Let's look at this from the standpoint of starting down the hill. The track will go STRAIGHT DOWN the hill as fast as it can - but it starts out on the level, and gradually starts getting steeper, as it descends further along the Great Circle. How far down can it go? It can go down to a point where the gradient reaches 4.0%, and then it has to curve over to one side, and start spiralling. That defines Point X, in terms of its (r) and (Z) coordinates. (It does not tell us about the angle, theta.) How can we describe this point X? It's a point where the slope (the tangent) is at 4 degrees. There, the radius (from the center of the hemisphere) is still exactly 1 mile, and the vertical elevation above the plain is exactly - 1 mile x cosine of (arctan 4%). About 0.999200958 mile. And, this is about 4.21894 feet closer to the plain, than the top of the hill. In other words, you only descend 4.21894 feet of elevation, before it has hit the 4% gradient. That's the view from the top. And this point is barely 211.2 feet from the top, before it has to curve. Now, starting from the bottom, every mile you ascend and travel, at a 4% grade, the horizontal distance is - cos (arctan4%). So when you travel one horizontal mile, the vertical ascent is 0.040000 mile, and the amount of track needed is - 1/cos (arctan 4%) - or about 1.00079968 miles When you need to spiral up to ascend a vertical distance that is exactly 1 mile x cos ( arctan 4%) - the amount of track needed is exactly 25.0000000 miles, to get UP to Point X. The value of cos (arctan 4%) cancels out, in both parts of the math - - - so you never have to know the exact value of this quantity. What is the distance from point X to the top of the mountain? Well, it is quite close to (4% of 1 mile), or 0.04 x 5280, or 211.2 feet. That is 4% of a mile. But the angle, in radians, is NOT 0.0400, but 0.039978687. That is the arctan of 0.0400. If you go in a straight line that would be (211.0734 feet) But since we are travelling along an arc with a true radius of 5280' - - the actual mileage from point X to the top, along the arc, is very close to 211.0875 feet. The TOTAL is quite close to 1 mile x [(1/.04) + (.04)], or 25.04000 miles, or 132,211.20 feet. That is a very good estimate. Actually you don't need 132,211.20'; 132,211.087 feet will be enough, so 25.0400 miles would be over by about 1.35 inches. But since this isn't even 1 ppm over, it won't cost Egbert too much. Nobody buys rail with an accuracy better than 1 PPM. To do that, you would need a very tightly controlled temperature-controlled rail-yard. http://www.national.com/rap/Story/solution.html (1 of 6) [3/23/2012 11:52:57 AM] Solutions to Mental Math Puzzles, Electronic Design, 31 March 2006 Problem 1.b. If you start on the exact west side of the mountain, heading north, from what angle do you approach the summit? In other words, at what angle is "point X"? I have no idea. My best guess is: About (XX) degrees.