The ‘smell box’ has finally arrived! It is based upon the same container as the prototype (so currently a bit large), and uses the same low power PC blower to move the air around. A 4N35 opto-isolator is used to separate the littleBits circuit from the circuit that powers the fan (which is controlled by a BC547), and the whole thing is powered by a 11.1V LIPO RC battery:
Similar to the Sound Box (see below) the Smell Box has littleBits circuitry integrated, and can be activated by any of the littleBits triggers:
The ‘smell’ itself is placed inside a small box embedded in the lid of the Smell Box. There are some ventilation holes drilled in the smell container (the off-white thing in the lid) and also a number of vents scattered around the box itself. It was tested with a piece of goat cheese:
To contain the smell of the cheese, the lid was pressed onto the smell container (which is almost air tight). However, the circulation was quite poor (despite the numerous ventilation holes), and so was tried again with the lid partially off:
This was better, and you could get a good sense of the cheese smell wafting from the box. But the design could be improved significantly in a number of ways:
- A much more powerful fan is required to get air circulating properly. A PC case blower seems to be a bit too weak for this purpose.
- The smell container needs to have some form of mechanism to contain the smell when the device is inactive. This could consist of a simple set of spring loaded flaps which isolate the smell, and which open only when the device is triggered and the fan starts.
- More ventilation holes in the main box, so that a good air volume is produced. Currently the air volume from the device is quite low, and so the smell is rather ‘subtle’.
- The air vent from which the smell emanates is currently to low down, and would ideally be placed on or near the top of the box.
We will trial this next week (18 Nov 2013) and see what happens with our target group. A report of how well it worked will be posted here soon.
In the meantime, we’ll be developing version 2 of the smell box, and include the improvements. Rather than hack boxes to pieces to make the new version, it would be a good idea to 3D print the next one. We’ll post the design on here when it is ready.