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Subject: 
fiber optics conduit to light sensors
Newsgroups: 
lugnet.robotics.scout, lugnet.robotics.microscout, lugnet.robotics.vll
Date: 
Fri, 26 Jan 2001 04:02:27 GMT
Viewed: 
11066 times
  
You can make a sturdy fiber optic cable conduit from Lego tubes and
connectors.  It can completely enclose at least two Lego fiber optic cables
joined  end-to-end from a light source to a light sensor.  The  conduit can
shield a light sensor from external light, join the ends of fiber optic
cables, and snugly fit on to certain Lego light sources and Mindstorms light
sensors.

Successful assemblies:  Tests of a length of 2 fiber optic cables end-to-end
in such a conduit successfully controlled a Micro Scout from a Lego Lamp.
Other successful combinations included the Scout and the LED's in the rotary
Lego FOS (Fiber Optic System).

Failures:  Tests using 3 cables end-to-end failed to trigger the sensors.

The parts of the conduit include:

Flex-System hose
http://img.lugnet.com/ld/75.gif

Pneumatic tubing

Technic Pin 1/2
http://img.lugnet.com/ld/4274.gif

Technic Pin Joiner Round
http://img.lugnet.com/ld/75535.gif

The following notes explain some of the characteristics and variations in
the conduit assembly.

The tubes come in 2 materials:  a) hard Technic Flex-System hose, and b)
soft pneumatic tubes.  The soft tube: 1) fits snugly over the hard tube, 2)
expands a small distance over the large end of the fiber optic cable, and 3)
allows bending of the fiber optic cable.  Precise cutting of the exact
length of the hard tube can prove difficult.  The soft tube forgives such
errors because it stretches or compresses where it fits over the hard tube.
The small ends of two adjacent fiber optic cables can touch inside either
type of tube to make a connection for light transmission.  The soft tube
fits over the Scout and Micro Scout light sensors.  The hard tube fits
firmly into either side of a pin until it reaches the flange inside the pin,
then it fits almost too tightly if pushed beyond.

A pin has a short side and a long side. The short side of a pin fits tightly
into the Scout's red LED hole and into any of the FOS rotary's LED holes.
The pin's short side does not have slits that could admit external light.
The long side of a pin snaps into a pin joiner.

A pin joiner connects the long sides of two pins, fits tightly over a Lego
Lamp, and holds tightly around a connection where a soft tube fits around
the end of a hard tube.

The large end of a fiber optic cable fits snugly into the long side of a pin
and stops at a precise position.  A pin joiner can enclose the large ends of
two adjacent fiber optic cables seated into pins this way so that the cables
touch inside the joiner.

Example conduit:  The small end of a fiber optic cable threads through a pin
joiner, the long end of a pin, a soft tube, a hard tube, the short end of a
second pin, a second pin joiner, the long end of a third pin, then stops
slightly before the end of the short side of the third pin.  The short side
of the third pin can fit into the FOS LED or Scout red LED or it can fit
into the Scout light sensor or the Micro Scout light sensor.  The first pin
joiner can fit over a Lego Lamp or snap over the long side of a pin from
another such assembly to make a conduit with 2 cables end-to-end.

Color:  Lighter colored tubes and pins joiners, especially at the light
source, produce better results in the 2-cable assemblies.  For example, a
test with a black pin joiner over the Lego Lamp failed to trigger the
sensor, but a yellow replacement succeeded.  The dark colors absorb too much
internal light.

Light sources & sensors:  The fiber optic 2-cable conduit works between the
following:
from Lego Lamp to Scout's light sensor;
from Lego Lamp to Micro Scout's light sensor;
from FOS LED to Micro Scout's light sensor;
from FOS LED to Scout's light sensor;
and maybe with the Scout's red LED, the Mindstorms Light Sensor, and the red
LED on the Mindstorms Light Sensor.

Parts Availability:

Fiber Optic Cable comes in accessory pack #5227 from LSAH and all sets with
"FOS."

FOS (Fiber Optic System) rotary 8-LED assembly with fiber optic cables comes
in the Extreme Creatures Expansion Set #9732, the  Fiber Optic Multi Set
#8456, the Space Shuttle #8480, Interstellar Star Fighter #6979, and
probably a few other sets.

Lego Lamp comes in the Mindstorms Ultimate Accessory Set #3801, accessory
Lighting Brick #5033 from LSAH, and train accessory Lighting Brick #5310
from LSAH.

Flex-System hose
http://guide.lugnet.com/partsref/technic/ LDraw 75
Available in many sets, mostly as decoration.

Pneumatic tubing
Available in accessory packs 5218 and 5109 from LSAH, in all pneumatic sets,
and in a few sets as decoration.

Technic Pin 1/2
http://guide.lugnet.com/partsref/technic/ LDraw 4274
Available in many sets as the pin without slits on the short side.

Technic Pin Joiner Round
http://guide.lugnet.com/partsref/technic/ LDraw 75535
Available in many sets as a decoration.

Micro Scout, Lego's simplest microprocessor "brick," comes in the Dark Side
Developers Kit #9754 and the Droid Developers Kit #9748.  It has  built-in
programs that do not require a PC and has a built-in light sensor.

Scout, Lego's intermediate microprocessor "brick," comes in the Robotics
Discovery Set #9735.  It has a built-in programs that do not require a PC
and has a built-in light sensor.

To fasten and guide the conduit through your model you can use parts
described by the keywords "connector" and "clip" at
http://guide.lugnet.com/partsref/keyword/



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