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The Operation Begins...
This is the core of the system and therefore the first part of the system we
get to take apart. The Logitech webcam is one of the best there is on the
market, with a flexible shapeable stand that we will have to use in an upcoming
project. One word for the wise with this project is to be vary careful with
dissecting electronics. Do not disassemble this project with it plugged into
your USB ports on your computer. Additionally, all circuit boards contain lead
and other potentially dangerous chemicals. Do not eat or handle food while or
after handling lead based circuit boards until you have washed your hands.
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So here is the
webcam disassembled. Removing outer casing, as well as unplugging the mic
and photo button on top, you should have as bare bones of a camera as possible
for this project. If you are planning on reinstalling the completed project
into the camera body I recommend keeping track of all the parts and screws.
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Here is a
close-up of the camera board and lens. The lenses is basically a plastic
housing screwed onto the board. The CCD the camera uses is actually
surface mounted on the board and the plastic housing helps to protect it from
dust and other contaminants. The lens is a variable focus lens and can be
turned left and right to adjust focus (done at the factory).
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By turning the
lens counterclockwise you can actually unscrew it from the board assembly. In
side the lens there is a lens that filters out infrared light that fills the
majority of the lens body. If you press on the clear lens lightly it will pop
the lenses out of the body making room for our radioactive components. Trash
the lenses as they are not needed for this project.
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Next up is the
disassembly of the smoke detector to obtain our alpha source. We purchased the
cheapest smoke detector we could find at our local hardware store. Now there
are some smoke detectors that do not use radioactive components. The cheap
detectors come in a paper box that can be opened. On the back side of the smoke
detector you will find printed information if it contains americium as well as
amounts.
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Using a flathead
screwdriver, depress the tabs on the back of the detector to remove the cover.
Inside you will see a lot of empty space and a circuit board with a large metal
housing on it.
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Carefully remove
the circuit board from the rest of the plastic housing. Our next step is to
remove the metal housing from the circuit board for disassembly. To do this you
could take the time to de-solder it and bend the metal tab, etc. I opted for
the faster method as on this unit the solder tabs are close to the edges of the
board. Using a good pair of wire cutters I simply cut through the board and
metal flanges in one simple stroke.
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With the metal
housing removed the inner components are wedged into place. Using a flat head
screwdriver pop the internals out of the housing. The tab at the bottom of this
image contains a small circular metal item with an indented center. The center
is the component that emits the alpha radiation, do not disassemble this. Just
remove this from the tab.
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Here is a close
up of the metal wafer. In the center of the wafer in the small indent there is
a small amount of the americium. The material around this acts as shielding and
we not only want to keep it for that reason, but also for the added ease of
mounting it into the lens. (Insert joke about glowing little green men here.)
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