The Nightlight – evolution of a key stage 3 project
The When I reached secondary school at the age of 11, the very first project I made in Technology (woodwork as it was then called) was a table lamp based on a halving joint. When I arrived at my present place of work, I was amazed to find that similar projects were still being made! Fortunately such projects have since been banished but a safe low voltage version could offer students a really interesting design project. With this in mind, I looked for ways to provide battery powered lighting projects that would be suitable and safe in a young child’s bedroom.
Last term we churned out 80 night lights which all proved to be very reliable for pupils to construct. It provides an excellent excuse for working in acrylic and using a CO2 laser cutter (which sadly we do not possess). Of all the electronic projects we have done at Key Stage 3, this night light has been the most popular by far. Pupils have even been overheard to say that they were “in no way” going to give away their night light, they were going to actually use them!
The problem with using battery power is that batteries quickly run down especially if the user falls asleep and leaves the light on overnight. I wanted an inexpensive design that could switch the light off automatically after 20 minutes. I settled on a 60mA 6V LES lamp – the sort often used in Christmas tree lights. This gives enough light to chase the shadows away and is economical enough to run from a battery of AA cells for over 10 hours. Fig 1 shows the required system.
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