Scratch Robots
Coin Sensor
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Scratch Robots
Coin Sensor – How does it work?
1) Build a long lever.
4) Build a platform
channel for a
quarter.
2) Attach one end
to a hinge.
3) Glue an arm to the lever as
near the hinge as possible that
rests on the Space Bar key.
5) When a quarter is dropped in the channel,
it pushes the arm down which presses the
Space Bar key. The quarter then rolls into
a can that collects the quarters.
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Scratch Robots
Coin Sensor Overview
Coffee stirrer stick
arm positioned to rest
on the Space Bar
Straw
8” coffee stirrer sticks
4”x4” cardboard
Find a book or block of
wood that is roughly
the same thickness as
your computer
keyboard. Tape the
book to the table and
tape your arm hindge
to the book.
3”x3” foamie hinge
The straws give you flexibility to
adjust the coin platform. Don’t
glue to coffee stirrer sticks!
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Scratch Robots
Coin Sensor
Materials:
Coffee stirrer sticks from Starbucks
Straws from Dunkin Donuts
Cardboard
Foamies
Masking tape
Tools:
Scissors
Hot glue gun
Ruler
Materials picture
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Scratch Robots
Coin Sensor – Step 1
1. Cut 4” square cardboard.
2. Break coffee stirrer sticks and hot glue to
cardboard. This will make a rigid platform.
Show how to break
sticks cleanly.
1. Instructions
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Scratch Robots
Coin Sensor – Step 2
1. Glue coffee stirrer sticks to a 3”x3”
square of flexible foamie.
2. Glue one edge of the hinge to the
cardboard platform.
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Scratch Robots
Coin Sensor – Step 3
1. Add sections to the lever until it is long
enough to span your computer key board.
8” coffee stirrer sticks
4”x4” cardboard
3”x3” foamie hinge
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Scratch Robots
Coin Sensor – Step 4
1. When the lever is long enough to span
your computer keyboard, create one last
section. Glue one end of the final section
but NOT the outside end !!!
Straw
8” coffee stirrer sticks
4”x4” cardboard
3”x3” foamie hinge
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Scratch Robots
Coin Sensor – Step 5
1) Insert the final section into the straw.
Straw
8” coffee stirrer sticks
4”x4” cardboard
3”x3” foamie hinge
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Scratch Robots
Coin Sensor – Step 6
1. Build a platform to channel a
quarter into a tin can. The straws
enable you to position the quarter
channel so it catches a quarter
from your model.
2. Build the quarter channel.
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Scratch Robots
Coin Sensor – Step 7
1. Glue or tape the quarter channel to the
platform on the straws.
2. Insert the lever ends into the straws on
the quarter channel platform.
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Scratch Robots
Coin Sensor – Step 8
1. Mount your lever on a book or block
of wood.
2. Tape the book or block of wood to
the table next to your computer
keyboard.
3. Glue an arm to the lever so that it
rests on the Space Bar key.
Be careful not to get glue on your
keyboard !!! Lift the lever away
from the keyboard.
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Scratch Robots
Coin Sensor – Step 9
1. Add a module that can drop
a quarter into the quarter
channel.
2. Position a cup or tin can to
catch the quarters.
3. Now you can write a
Scratch program to play
audio clips and control a
black or white square on
the computer screen.
When the square is black,
your motor controller will
turn a motor off.
When the square is white,
your motor controller will
turn a motor on.
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