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HP48 Keyboard Scanning and Electrical Resistance


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Post: #2
03-17-2008, 11:57 AM
Thomas Chrapkiewicz Offline
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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

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Post: #3
03-17-2008, 12:11 PM
Randy Offline
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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

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Post: #4
03-18-2008, 07:59 AM
Thomas Chrapkiewicz Offline
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Randy:
Excellent resource! Thank you very much!
TomC

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