Capacitive touch problems

Sensors
1

I’m having real trouble with a capacitive touch installation in a museum I was tasked with. I guess I don’t really have the knowledge of electronics to manage this, but I have to regardless.

I have 4 sparkfun redboards, each of them has ten at42qt1010 capacitive sensors connected to digital pins 2-11. Each of the capacitive sensors has a short wire soldered to the “pad” pinout, and that wire is resting underneath a stainless steel plate with names engraved. visitors touch these stainless steel plates to see information about the person on a large projection. all the redboards are connected to the computer directly through usb.

A couple of weeks ago the museum had a power surge or something (it is unclear to me what exactly happened, I do not work here) and two of the redboards failed, none of the sensors work. They are both still lighting up when powered, and all of the sensors still light up when touched. The computer does not recognize them however. I took the two broken redboards back to my shop and burned the bootloader on them, and they were recognized by the computer again. I was able to reupload the code and tested one sensor that I had, and they worked fine.

I brought them back to the museum today to reinstall with all ten sensors, and once I attached all the sensors and plugged them back in, the computer does not recognize them. I tried different usb ports, nothing. There are two other redboards in this system that still work, so I am not sure what is going wrong with these two specifically, and I am out of ideas. This is not the first time I have had to come back here to repair this system. It was working without issue for about 7 months until now.

What could have caused this issue and how can I fix it? As a crutch I am just going to replace the redboards with new ones and see if that solves the problem but I need it to last much longer than 7 months. I don’t want to keep coming back here and pouring money and time into this. Any advice would be greatly appreciated… thank you.

2

It sounds like whatever power surge happened may have damaged those 2 boards :-/

You could power the PC that is powering them with a UPS or something….or a usb isolator for power…the main issue is the need to mitigate the potential power surges. You could also probably put them on a large battery bank that is isolated from the main circuit and only use the 2-11 pins to the PC

But there isn’t a lot to be done on the boards themselves in this case :-/

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3

:frowning: Thanks for the advice. I’ve ordered two replacement boards. Buying a UPS seems like an accessible prevention step as well. Does this work better than a regular surge protector power strip?

4

Yes, they are superior….the power reserve amount and backup times will vary by model but some can withstand 8+ seconds of lost power. This should help prevent any brown outs on attached devices

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5

Surge suppression is generally a lot better on a UPS than on a power strip as well since they are typically used with computers and those are more prone to damage by surges.

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