HP Forum Archive 18

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HP48 Keyboard Scanning and Electrical Resistance Message #1 Posted by Thomas Chrapkiewicz on 17 Mar 2008, 11:57 a.m. The keyboard of the HP48 is scanned as somewhat documented in the available schematics. Can anyone explain (or direct me to the appropriate links) why the keyboard contact paths have a significant (kilohms) electrical resistance? Regards, TomCee

Re: HP48 Keyboard Scanning and Electrical Resistance Message #2 Posted by Randy on 17 Mar 2008, 12:11 p.m., in response to message #1 by Thomas Chrapkiewicz Documented in US Patent 5,065,356. You'll find a copy posted on Eric's site here: PDF of HP Patent 5,065,356

Re: HP48 Keyboard Scanning and Electrical Resistance Message #3 Posted by Thomas Chrapkiewicz on 18 Mar 2008, 7:59 a.m., in response to message #2 by Randy Randy: Excellent resource! Thank you very much! TomC

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