We’ve been working on a couple new ideas for the triggers. The first is a touch activated switch. I put some aluminum tape on the top of the soap dispenser and connected it to a capacitive sensing circuit. It works most of the time, but occasionally misses. We might be able to balance the sensitivity and reliability of this, but we’ll need some way to make the top of the bottle conductive.
A single lead connects the evaluation board for the PCF8883 (the UM10370 board from NXP Semiconductor) capacitive proximity switch to the aluminum tape on the lever. A light touch triggers the indicator light.
The second idea is to use a magnet to trip a reed sensor located inside the bottle. This seems like a very convenient technique, but we’re not confident that we can get the right combination of magnet and reed sensor so that we can make a repeatable process that doesn’t require lots of tweaking. The magnet goes inside the plunger mechanism and the reed goes on the outside of the foaming chamber. This demo seemed to work pretty reliably, but required a movement of several mm before actuation. Some minimum distance is required because there appears to be some hysteresis in the mechanism.
Gregg holds the demo he assembled. The rectangular magnet sits in the gap between the clear plastic and the white top of the lever. In the working demo tape holds the reed switch connected to the two leads. When the magnet is close to the reed switch, it closes, which could trigger the mote.
