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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
Standard 3.5mm 2-pin switched mono microphone jack; selectable 2V DC bias; selectable sensor-input mode (DC or AC coupled); selectable +20dB boost.
Standard 3.5mm 2-pin switched mono microphone jack; selectable 2V DC bias; selectable sensor-input mode (DC or AC coupled); selectable +20dB boost.
On the XO-1, mono data is measured, the left channel, the tip (usually the red wire). The XO-1.5 and the XO-1.75 can read both the left and right channel.
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 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.
<i> 680 ohm series resistor on a 3.5mm audio plug</i>
<i> 680 ohm series resistor on a 3.5mm audio plug</i>
Test leads with a zener diode and series resistor would expand the safe range for the XO1.5 and XO1.75.
Test leads with a zener diode and series resistor would expand the safe range for the XO1.5, XO1.75, XO-3 and XO-4.
Damage can also be caused by applying voltages between the grounds of any of the external sockets.
Damage can also be caused by applying voltages between the grounds of any of the external sockets.
(* 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
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.
==Pitch Mode==
==Pitch Mode==
== 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]]
R = T/C
R = T/C
= 0.14 /(4x10^-6) = 35k
= 0.14 /(4x10^-6) = 35k
[[File:Rc-time.jpg]]
[[File:Rc-time.jpg]]
[[File:RC data to clip.jpg]]
[[File:RC data to clip.jpg]]
See also a similar experiment which uses the [[Activities/TurtleBots#Buti.C3.A1|USB4Butia]] board (in Spanish) http://youtu.be/eewFtOHX5-Q and http://youtu.be/KmNwC1qBhtA
==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 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==