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Activities/Turtle Art/Using Turtle Art Sensors (view source)
Revision as of 21:55, 19 December 2012
, 21:55, 19 December 2012→Voltage-current relationship
==Voltage-current relationship==
==Voltage-current relationship==
Some devices including light bulbs have non-linear voltage current relationships. In this experiment, the V-I graph of a light bulb is drawn.
Some devices including light bulbs have non-linear voltage current relationships. In this experiment, the V-I graph of a light bulb is drawn using the stereo input of the XO-1.5.
[[Image:VI Turtle Art.png|400px]]
[[Image:VIgraph.jpg|250px]] [[Image:VI Turtle Art.png|400px]]
See http://youtu.be/37vJEUr5nRI and http://www.youtube.com/watch?v=_iSXHsGvLaY (in Spanish) for experiments plotting linear and nonlinear V-I relationships using the [[Activities/TurtleBots#Buti.C3.A1|USB4Butia]] board.
The light bulb and resistor were chosen thus. The maximum measurable input of the XO-1.5 is +3V, at maximum you want approximately 1.5V across the resistor and 1.5V across the bulb, the bulb should be near full brightness. A 2.8V 0.85A torch/flashlight bulb was used. The estimated resistance of the bulb is V/I, 2.8V/0.85A = 3.3 ohms, chosing from resistors at hand, trial and error found 2.2 ohms was OK. The power rating of the resistor is V*V/R, 1.5*1.5/2.2 = 1.02W, a resistor of 1W or higher rating is required.
The X axis is voltage across the bulb, voltage2 - voltage, the Y axis is the current which is proportional to the voltage across the resistor or the L channel voltage.
See also http://youtu.be/37vJEUr5nRI and http://www.youtube.com/watch?v=_iSXHsGvLaY (in Spanish) for experiments plotting linear and nonlinear V-I relationships using the [[Activities/TurtleBots#Buti.C3.A1|USB4Butia]] board.
==The XO as an audio amplifier==
==The XO as an audio amplifier==