Thanks to David Tweed's index of CircuitCellar articles, I located references to
 Brian Kenner's publication on the topic.

http://www.sss-mag.com/pdf/maxej22.pdf
page 8

Same stuff as an app note.
http://www.maxim-ic.com/appnotes.cfm/appnote_number/647

Should get you started.

Robert

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