by Guzman Trinidad http://sites.google.com/site/solymar1fisica/fisica-con-xo-investigacion-
by Guzman Trinidad http://sites.google.com/site/solymar1fisica/fisica-con-xo-investigacion-
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== Hall Effect Sensor ==
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A Hall Effect sensor such as the (Allegro) UGN3503UA Hall Effect Sensor http://www.jaycar.com.au/products_uploaded/ZD1902.pdf ($6ea.) can be used to measure magnetic fields. (The Allegro1302 http://www.alldatasheet.com/datasheet-pdf/pdf/120806/ALLEGRO/A1302EUA.html is an alternative to the Allegro3503).
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The sensor requires +5V, this is available from the XO's USB connectors.
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[[File:PinoutUSB.jpg]] [[File:Usb5v.jpg | 150px]]
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(<i>image http://www.homebrewusb.com</i>)
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see also http://wiki.laptop.org/go/Making_XO_sensors/How_to_connect_sensors
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The sensor has an output of half supply voltage (2.5V) at zero magnetic field with a sensitivity of 1.3mV/Gauss. This makes it suitable for connection to the XO1.5 (input range 0.17 - 3.3V). For the XO1.0 (input range 0.4 - 1.85V ) a 2:1 voltage divider is necessary.