In a recent article, I went over how to use the Glade automatic air freshener for your own purposes – triggering a camera in this case. Per some of the comments on this site and elsewhere, there is some interest in using the Sense and Spray model to do the same thing. I was interested myself, so I bought one and took it apart.
The main reason suggested for using the Sense and Spray is that it has a sensor that can supposedly pick up movement and actuate based on this. The other very good argument is that is costs around $5, where the automatic timer version costs around $10. If you have to use several of them, this cost could add up.
The two models are similar in that they both use 2 AA batteries in series for a 3 volt power supply. Additionally, they share a very similar motor and gear reduction setup. The sense and spray version uses standard Phillips head screws throughout so you won’t have to worry about getting a non-standard bit or screw extractor to take it apart.
From a hacking perspective though, there are some drawbacks to the Sense and Spray model. The first is that the gearbox is more compact and stays in one piece better on the automatic spray version. The sense and spray has a “tongue” that is pulled in using the motor, but is not constrained without the housing. The gearbox on the auto spray is in one package and stays together quite nicely when taken out of the housing. It also has some very convenient mounting holes circled in blue to the right.
The second advantage to the automatic version is that it has the circuit board, trigger button, and timing circuit are in separate pieces. This can definitely be useful depending on your project.
Finally, I don’t think the “proximity sensor” on the Sense and Spray works as one would expect. After reading the back of the box, it seems to work on sensing shadows in a room and not by actual proximity (how this is supposed to work in the dark, I don’t know). Additionally, it will only spray automatically once every 30 minutes. This could be circumvented by wiring some sort of timer or microcontroller to the button, but that would kind of defeat the purpose of using it.
The Sense and Spray model does have it’s advantages and probably has it’s uses as a hardware source. However, in my opinion, the automatic spray version is the thing to buy if you want to modify it. For the other 99.99 percent of people who just want to buy an air freshener, either would be fine – not that those people, if they somehow stumbled upon this blog, have read this far.