Download - Year 9 Light Sensor Project V2
AGSB
2011
Light Sensor Project Design & Technology
James Persico 09JY
Brainstorm
Light Sensor
Fire exit lights
Emergency lighting
Power cut light backups
Amount of light
reaching crops
Photographer’s light meter
Light Pollution
These light up when
there is not enough
light to show them
clearly enough.
Fire exit lights often
contain a light sensor
unit that activates the
light when electricity
fails, and people need
to find an exit.
Environmentalists can
measure the amount
of light pollution
caused by
streetlights/floodlight
shining into the sky.
Photographers use light sensors
to measure the average amount
of light in an environment to help
them decide shutter speed, ISO
speed and aperture.
A farmer could work out how
much light his crops are
receiving. If they are placed in a
shaded location, he can see if
there is still enough light reaching
the crops.
Problem I believe my local area contains levels of light pollution well above those necessary for safety. I want
to conduct a science experiment to measure levels of light pollution in urban, sub urban and rural
locations, to see if there is a noticeable difference. Light pollution can ruin health, as clinical studies
have shown that the body needs an extended period of darkness to be able to sleep well, and
damages nighttime views of the Milky Way, now invisible in most of the UK.
Brief I need a light sensor capable of detecting light and indicating the level of light by giving a reading in
some way. I need it to be robust, portable, and reliable, for the purposes of my experiment.
Example of light pollution (source: moblog.com)
Specifications
MUST
It must detect light - Crucial to the entire project
It must be fully functional – No parts must be faulty or irregular.
It must use a 9V battery – This is what the circuit runs on
It must have an on/off switch – To save battery power
It must have all components enclosed and secure inside the case – To keep everything
together
The case must have no convex corners <20mm or concave corners <80mm – To avoid over-
curved or over-sharpened edges.
The base must be secure – To avoid the contents falling out.
The product must be finished well – To ensure a professional look and maximum safety
The 4 LEDs must be in a sensible order or colour – Easy to understand colours help the user
operate the sensor better without having read the manual
All wires must be secured using securing holes – To ensure safety and rigidity
Have a moulded top – To provide an aesthetically pleasing design
SHOULD
Be portable – To expand the device’s uses
Be durable – To withstand the small knocks of daily use
Have easy access to the battery – So the user can replace a dead battery with ease
COULD
Have a logo – To improve appearance
Include accessories – To aid in using the device
Final Idea
Sunrise, indicative
of light
LEDs, indicate
level of darkness.
Robust cylindrical
design.
Switch
Light detecting
resistor
Finished Product
The product also comes with a free gadget to open the back of the device, allowing the user to
change the battery when the one supplied is exhausted.
Testing the device
In a dark location (cupboard)
Testing the device under a standard sodium streetlight. The LEDs show that the lighting level is
above reasonable darkness, and that light pollution is taking place. A satisfactory level of lighting
would mean all lights would be lit up, while the red one is clearly out in this picture.
Evaluation
Mould Design I think the mould design was one of the best aspects of the product, reflecting its intended purpose
while not looking loud or messy. The black colour I chose helps the user distinguish between the
lights and the plastic when the product is in use.
The circuit I improved on the work I had done with the PICAXE project in Year 8, and my soldering was, overall,
much tidier. I only had one overflow of solder, and this was easily fixed inside a minute. In future I
could start to concentrate on my speed, as this became a small issue towards the end of the project.
The logo I used the skills I learnt from the Clinometer project to help me produce a Sticka logo for the
product, again in the name ‘Delta Tech’. I could have improved by increasing the size of the font,
this would have wasted less material, as I had to scrap some messy and badly cut Stickas, simply
because the machine was finding my drawings too small.
The back removal panel The panel hole used to remove the back to replace the battery can also be used to hang the light
sensor on a wall, so as to measure general room lighting, which is an added bonus. However, the
back could be finished better, so there is room for improvement.
Conclusion Over the course of the project I have used many skills acquired from the previous project, and
revised ones from projects I did several months ago, like vacuum-forming and PCB drilling. I finished
the product in time, and it is in full working order, as shown in the pictures. I have also managed to
solve my problem of testing light pollution, and may use the results as evidence if I decide to follow
up the matter with my local authority.
The product has met its specifications and has shown it can be used flexibly in other scenarios too.