weatherproof user button

[devnull]

Had a mqtt based unit deployed outside for the last 1 year, overall worked very well but I would like to eliminate the existing led-button (expensive sealed button with led in centre) with some kind of prox instead to improve weatherability.

As I see there are 2 'proximity' options, either use a hall effect device & magnet, or try and sense a finger proximity, but I am doubtful this can be done through a 2mm thick transparent lid which would be used in place of the old lid which was not transparent.

I need to distinguish between short and long press and right now am feeling that the hall-effect is probably the only reliable way.

Any ideas / suggestions / comments ??

[pythoncoder]

I share your doubts about proximity sensors as these are capacitive and rainwater is conductive. That is likely to be more of an issue than 2mm of plastic. Mind you I can't back that up with any measurements, experience or references.

If commercial weatherproof buttons are too expensive I wonder if there's scope for applying physical pressure to a normal button through a waterproof membrane?

[rsmith]

I've seen capacitive sensors work as proximity sensors through approximately 4 mm of plastic on medical devices. Those machines are for indoor use, but they can be cleaned with liquids. The conductive surfaces on the inside of the plastic were quite big in that case; in the order of 100 cm2.

You could put the opening of a small black tube against the inside of the translucent cover. And seal the other opening with a light sensor. Cover the tube with your finger to cut off the light and give a signal.

Of course this alone would not work at night. Maybe add an infrared LED next to the sensor so that your finger reflects some of the light?