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Each nesting box is fitted
with a small ccd video camera. The camera has a built in microphone so we
can hear what is going on as well. We have mounted the cameras in small
plastic housings along with 4 infra-red light emitting diodes. These
cameras are usually used for security systems but can easily be adapted
for other purposes.
The pictures are only
black and white because the camera has to be able to see in the 'dark'.
In fact, it is not really 'dark' because the inside of the nesting
box is lit by infra-red light which the camera can see. Like us, the birds
cannot see the infra-red light so are not disturbed by it.
The output from the
cameras can be connected directly to a standard television, video recorder
or a tv/video card in a PC.
For the pictures on these
web pages we are using a video capture card in the PC to take snapshots of
the activity.
Details of
camera and parts list.
The following shows how
the camera is put together but does not give full construction
details.
Picture 1.
Picture 1 shows the
completed camera. The four screws you can see hold the metal posts
that support the camera circuit board. To give you some idea of
scale, the distance between these screws is 32mm. Just outside the
screws you can see the four plastic lenses that cover the infra-red
LEDs. These lenses just snap into holes drilled through the plastic
box. The microphone is held in place by a rubber grommet just to
the left of the camera lens. The three small holes have been made to
allow air circulation through the camera box.
Picture 2.
Picture 2 shows the camera
with the back removed from the plastic box. You can see the four
screws that attach the camera circuit board to the metal mounting posts.
The blue terminal block on the left hand side is soldered to a small piece
of veroboard which is inserted through a slot cut into the plastic
box.
Picture 3.
Picture 3 shows the camera
circuit board removed from the mounting posts. You can see the two small
pieces of veroboard that have the infra-red LEDs and resistors soldered to
them. These are held in place by the slots that are part of the plastic
box and also by clipping the LEDs into the plastic lenses that are fixed
into holes in the front of the box. You can also see the microphone that
is fixed into the front of the box by a rubber grommet. This
was removed from the camera circuit board and re-attached using a short
length of cable. This was done to try to improve the sound
quality.
Picture 4.
Picture 4 shows one of the
small pieces of veroboard with two of the LEDs and the resistors that are
used to drop the voltage for them. The resistors run fairly hot which is
one of the reasons for making the small ventilation holes in the plastic
box. One benefit of this heat is to keep the camera box free from
condensation :-)
Parts
list
- B/W camera module 206L
from Henry's.
- Other parts from Maplin.
- Siemans SFH487 GaAlAs
high power infra-red emitting diode (x4)
- LED cover, clear
(x4)
- Metal film 0.6W
resistors, 150 Ohm (x2)
- Piece of
veroboard
- Low profile 301
series PCB terminal block, 4 way
- ABS box H2855
- Standard grommet, 9.5
mm
- M3 6 mm steel screws
(x4)
- M3 10 mm steel screws
(x4)
- M3 threaded spacers
(x4)
- Four-core lapped
screen cable, black
- Peritel (SCART)
plug
- Also required is a
regulated 12 volt power supply rated at least 300
mA.
Construction could be
simplified by not removing the microphone from the camera module.
This bit is tricky as it is soldered on to the very tightly packed circuit
board. Fitting the grommet and the microphone to the front of the
plastic box is also a bit fiddly. Fitting the terminal block is also
a bit fiddly but once done this provides a very easy method of installing
and removing the camera.
If you use an alternative
camera, make sure that the lens can be adjusted. Most cameras will
be supplied with the focussing set from infinity down to about one
metre. Obviously for the bird box this will need adjusting so that
it can focus down to just a few centimetres.
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