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Article #2714Resistor Puzzle
From: Alan Wm Paeth
Date: Fri, 25 Nov 1988 23:02
Date: Fri, 25 Nov 1988 23:02
16 lines
1138 bytes
1138 bytes
Scenario: A resistor decade allows the selection of one through ten ohms.
Typical internals are ten one-ohm resistors and a 10-pole switch. A more part-
efficient design (ignoring switch complexity) might use four resistors of
binary weights (1,2,4,8) thereby extending the range to fifteen ohms.
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PUZZLE: using four resistors construct a "decade" good for (at least) the
range 1 to 16 ohms, inclusive. No restrictions on wiring or resistor values.
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Reminder: resistors in series sum values, eg: (4+4) = 8. Resistors in parallel
sum their inverse values (1/a+1/b=1/sum), eg: (4|4) = 2.
/Alan Paeth
Computer Graphics Laboratory
University of Waterloo
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!watmath!watcgl!awpaeth From: awpaeth@watcgl.waterloo.edu (Alan Wm Paeth) Newsgroups: rec.puzzles,sci.electronics Subject: Resistor Puzzle Message-ID: <6951@watcgl.waterloo.edu> Date: 25 Nov 88 23:02:37 GMT Distribution: rec Organization: U of Waterloo, Ontario Lines: 16