LFS: pressure pad switch/mat switch - Page 1
Forum section: electronics / general

author: edavid
author_rank: Super Contributor
timestamp: October 13, 2023, 06:36:05 pm
content: I am looking for some small pressure pad switches for an exhibit.My ideal specs would be something like:size 2"x2"actuation force < 5lblife > 10K cyclescost < $10 eachThis is about the closest I've found, but is too large and too expensive:http://us.rs-online.com/product/rs-pro/9184766/71013816Does anyone have a good source?I have also seen "force sensitive resistors" like this in different sizes:https://www.sparkfun.com/products/9376Has anyone used them in an application where they were literally stepped on?

author: thm_w
author_rank: Super Contributor
timestamp: October 13, 2023, 09:20:54 pm
content: 2x2 inch is very small for a mat switch. I wonder how the RS one works as its so thin (3mm).Hoverboards use a optical interrupter switch and rocker/spring mechanism, but you'd have to build that yourself.I wouldn't trust the FSR unless you are willing to build a protective structure around it that limits force. Maybe a plate on the bottom and plate and rubber mat on the top or something. The datasheet for those normal pads say cover with carpet or rubber mat.https://www.aliexpress.us/item/3256805509401596.html

author: edavid
author_rank: Super Contributor
timestamp: October 13, 2023, 10:31:22 pm
content: Quote from: thm_w on October 13, 2023, 09:20:54 pmHere's one that's only 3/4" wide and can be cut to length (but it's very expensive):https://www.mcmaster.com/7379K1QuoteI think that would be thick enough that I would have to build a raised platform. With the pressure pads, I could just put a yoga mat sort of layer over the top.QuoteI was hoping someone had already worked out what was needed

author: thm_w
author_rank: Super Contributor
timestamp: October 13, 2023, 11:11:47 pm
content: Oh that strip switch looks nice. They show some of the construction here:https://www.switchesandsensors.com/strip-switch-continuous-switcheshttps://www.tapeswitch.com/support/manuals/ControlMat_Manual_Ver.3.3.pdfhttps://www.tapeswitch.com/support/downloads.htmlI'm still not sure why it has to be small though, do you have multiple side by side that will activate a different effect?

author: edavid
author_rank: Super Contributor
timestamp: October 14, 2023, 01:54:54 am
content: Quote from: thm_w on October 13, 2023, 11:11:47 pmThat's right, we want to have literal footprints that the guests (mostly children) will step on to activate effects. There's some flexibility on the size and density though.

author: FoxtrotOfIndia
author_rank: Contributor
timestamp: October 14, 2023, 12:24:24 pm
content: mechanical stuff with kids jumping on it (and they will jump even if they are glued down) does not sound like something that will work for long.have you thought about capacitive touch sensors? the size of foot contact area should allow it to work with a much thicker cover over it than would be possible with finger touch sensing.most microcontroller product ranges have something with capacitive touch io.

author: edavid
author_rank: Super Contributor
timestamp: October 14, 2023, 03:16:29 pm
content: Quote from: FoxtrotOfIndia on October 14, 2023, 12:24:24 pmIt only has to last a month, which I think is possible with industrial grade switches. There will be docents so the kids can't run completely wild.QuoteI didn't think there would be enough SNR to make it reliable, but you're right, I should do some testing.

author: _Wim_
author_rank: Super Contributor
timestamp: October 15, 2023, 07:31:26 am
content: It might be worth to try with simple membrane switches (https://www.aliexpress.com/item/1005004283312153.html?search_direct=true&spm=a2g0o.productlist.0.0)If you glue the back to a flexible layer (like a thin yoga mat) with the dome facing downwards to the floor, I think it might be possible the activate these when stepped on (have not tried). You can wire some in parallel to define the the size of the zone you want to detect. Lots of wiring work though, but very inexpensive.

author: Kean
author_rank: Unknown
timestamp: October 16, 2023, 05:49:29 am
content: You mentioned covering with a yoga mat, so one possibility is piezo sensors with some cork or foam backing - similar to those used on some DIY drum kits.https://www.sparkfun.com/tutorials/330

author: edavid
author_rank: Super Contributor
timestamp: October 16, 2023, 03:24:32 pm
content: Quote from: Kean on October 16, 2023, 05:49:29 amInteresting idea, but I need something that responds to static pressure, rather than a strike.