Given that today's smartphones are mobile and have more computing power and means to measure the external world than early PCs, they may also revolutionize data collection, both in structured physics laboratory settings and in less predictable situations, outside the classroom. Several examples using the internal sensors available in a smartphone were presented in earlier papers in this column.1, 2 But data collection is not limited only to the phone's internal sensors since most also have a headphone port for connecting an external microphone and speakers. This port can be used to connect to external equipment in much the same way as the game port on the early Apple II was used in school labs. Below is an illustration using the headphone port to receive data from an external circuit: smartphones as a portable oscilloscope using commercially available hardware and applications.

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HMB-TEC; hmb-tec.de/iPhoneApps/iPhone_Apps.html. The company lists a number of other external probes (temperature, IR probe, laser pointer, etc.) as available, but many of the items listed are not actually for sale yet.
4.
We tested SignalScope (www.faberacoustical.com/products/iphone/signalscope_pro/), AudioScope (www.hensley industriesllc.com/iphone/audioscope/audioscope.html), and oScope(itunes.apple.com/us/app/oscope/id344345859?mt=8), temporary web address.
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