Re: 82104A card reader current measurements? Message #5 Posted by Michael de Estrada on 10 June 2009, 5:56 p.m., in response to message #4 by Eric Smith
Here's some preliminary info based on a HP65:
Applied voltage at battery terminals - 3.75 Vdc
1) Calculator powered on and idle - display 0.00 - 140 mA
2) Calculator during a card read - 300 mA
3) Net current draw of card reader = 160 mA
Note that the current draw initially peaks as high as 450 mA as the motor does extra work grabbing the card and overcoming initial static friction (sliding friction is less). Also, I imagine this will vary between different card readers based on the tightness of the drive roller. If you are interested, I will test other calculators as I have 3 HP65's, 2 HP67s and a HP97. Also, all of these have been refurbished, so I have no baseline to the original.
Edited: 10 June 2009, 6:02 p.m.
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