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Activities/Turtle Art/Using Turtle Art Sensors (view source)
Revision as of 03:58, 21 November 2013
, 03:58, 21 November 2013→XO-1.75
On the XO-1, mono data is measured, the left channel, the tip (usually the red wire). The XO-1.5, XO-1.75, XO-3 and XO-4 can read both the left and right channel. (Currently on the XO-1.75, XO-3 and XO-4 stereo input is disabled).
On the XO-1, mono data is measured, the left channel, the tip (usually the red wire). The XO-1.5, XO-1.75, XO-3 and XO-4 can read both the left and right channel. (Currently on the XO-1.75, XO-3 and XO-4 stereo input is disabled).
The XO-1 is protected at the input by a 5V zener diode. The allowable input is -0.5V to 5V. Inputs outside this range will cause excessive current and damage. Even a single 1.5V battery can cause damage if connected reverse polarity.
The XO-1 is protected at the input by a 5V zener diode. ([http://wiki.laptop.org/go/File:XO-1_Schematics.pdf 1]) The allowable input is -0.5V to 5V. Inputs outside this range will cause excessive current and damage. Even a single 1.5V battery can cause damage if connected reverse polarity.
The XO-1.5 and XO-1.75 (XO-3 and XO-4 presumably too) are protected by a resistor,(1/16W 470 ohm SMD0402) and a pair of diodes to ground and to +3.3V which should protect -6V to +9V continuously, and up to higher voltages for shorter periods of time.
The XO-1.5 ( [http://wiki.laptop.org/go/File:XO-1.5_Schematics_rev_G.pdf 2] [http://wiki.laptop.org/go/File:XO-1.5_Schematics_rev_I.pdf 3] [http://wiki.laptop.org/go/File:XO-1.5_Schematics_rev_M.pdf 4] )and XO-1.75 (XO-3 and XO-4 presumably too) are protected by a resistor,(1/16W 470 ohm SMD0402) and a pair of diodes to ground and to +3.3V which should protect -6V to +9V continuously, and up to higher voltages for shorter periods of time.
For the XO-1, the addition of a 150k ohm series resistor would (I expect, no guarantee) give a reduced sensitivity in voltage mode (0-4V) but allow inputs to +- 100V without damage. Input impedance in resistance, volume and pitch modes is much lower but a 1k ohm series resistor should still allow inputs to +-12V.
For the XO-1, the addition of a 150k ohm series resistor would (I expect, no guarantee) give a reduced sensitivity in voltage mode (0-4V) but allow inputs to +- 100V without damage. Input impedance in resistance, volume and pitch modes is much lower but a 1k ohm series resistor should still allow inputs to +-12V.
(* A small number of pre-production laptops were built with -3V to +3V input range and input impedance 1k ohm to a +3V bias, eg. model SKU199. Turtle Blocks V141 and previous is correctly calibrated for these laptops but not for production laptops)
(* A small number of pre-production laptops were built with -3V to +3V input range and input impedance 1k ohm to a +3V bias, eg. model SKU199. Turtle Blocks V141 and previous is correctly calibrated for these laptops but not for production laptops)
===XO-4===
Two channels, 0 to 3V. At the time of writing, as a workaround to a bug with dual channels, apply the input to both channels, only a mono reading is available.
==Resistance Mode==
==Resistance Mode==
===XO-1.75===
===XO-1.75===
Two channels, zero ohms to open circuit. At the time of writing, as a workaround to a bug with dual channels, apply the input to both channels, only a mono reading is available.
===XO-4===
Two channels, zero ohms to open circuit. At the time of writing, as a workaround to a bug with dual channels, apply the input to both channels, only a mono reading is available.
Two channels, zero ohms to open circuit. At the time of writing, as a workaround to a bug with dual channels, apply the input to both channels, only a mono reading is available.
== RC time constant ==
== RC time constant ==
IT IS RECOMMENDED THAT A SERIES PROTECTION RESISTOR BE BUILT INTO THE PHONO PLUG AND LEADS IF USING AN EXTERNAL VOLTAGE
IT IS RECOMMENDED THAT A SERIES PROTECTION RESISTOR BE BUILT INTO THE PHONO PLUG AND LEADS IF USING AN EXTERNAL VOLTAGE WITH THE XO-1
[[File:Rc cct.jpg]]
[[File:Rc cct.jpg]]
==Voltage-current relationship==
==Voltage-current relationship==
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. This experiment should be possible using just the XO-1.5 which has stereo input.
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:VIgraph.jpg|250px]] [[Image:VI Turtle Art.png|400px]]
[[File:Turtle Art Activity VI.ta]]
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.
A laboratory power supply was used in this experiment. It is safest if its output is within the maximum allowable voltage range of the XO-1.5, -6 to +9V. Low cost options would include a selection of dry cells in varying states of discharge. It may be practical to construct a variable resistor using a pencil lead.
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==