force sensitive resistors to detect touch on a panel?

Hey guys,

i want to make a custom controller to select different shower heads in my shower.

I have 3/4 solenoid valves hooked up behind each shower head but am having issues with making a professional looking waterproof interface.

I was wondering if i had a glass panel with 4 risers

set in from each corner, like this (but on a smaller scale):

if i set up the risers to push against 4 force sensitive resistors (with a spring to maintain lateral pressure when not being pressed) . would i be able to detect which area of the glass was pressed based on which resistor has the greatest change? There are only 4 buttons and they would be evenly spaced out in a 2x2 configuration (or 1x4)

this is the resistor i was thinking of getting: http://www.sparkfun.com/products/9673

based on which resistor has the greatest change?

This sounds workable. There are touch sensors that react to body capacitance also, some of which can be applied to glass. But your idea puts the electrical stuff away from the shower.

See the "waterproof Spa controls" on some hot tubs??

thanks for the feedback. still pretty new to the arduino and even programing but with the arduino knowledge base online and things i’ve been able to figure out so far, i think this is something within my grasp.

I checked out spa controls but (to try to hack into also) but they all were membrane swiches. I also looked into the mtouch waterproof capacitance ic’s, but i think thats a bit over my head.

how would the glass only be able to touch one area? unless it where flexible , because im thinking lets say you press on the bottom left corner you can only press it so far andmaybe not even all the way before the top right corner gets "locked" by the spacer because it will be at an angle...i dont know if that made sense but try to to picture it

unless you made them smaller and used a full square for each "option/button" so if you had 4 buttons you would have a sqaure with 4 different and sprate sections something like this where each section is a sqaure with its own spring and spacers.. |______________ | | | |------|---------- |___|___|

have you seen these push buttons they are water proof and illuminated..but pricey @ $11.50 each

http://www.dfrobot.com/index.php?route=product/product&path=66&product_id=440

I think you’re thinking of a digital button. instead i’d be using variable resistors. with one on each corner there should be some correlation between where you press it and which force sensor changes the most. also, im not looking for the glass panel to actually have any real feedback. The standoffs would be mounted with a rubber (or softer material) o-ring that would compress slightly. So say i press the top-right quarter of the glass. this should put slightly more pressure against the sensor that is in that corner. I’d have the arduino monitor they inputs and when it detects one of the force sensors having a larger change… it would toggle a relay.

Another option would be to find a resistive touchscreen that is large enough to cover your glass, the drawback is then there's 4 wires to hide, but the arduino can accuratly read those, you could make multiple buttons, maybe etched into the glass and map it,

I think that if a person presses the glass close to the center it would be difficult / imposssible to tell which quadrant was actually pressed

Im not sure how its affected by water, but perhaps capacative sensors could be another option? You can make them sensitive to read through the glass

the resistive panel is an option that i've been tossing around. to make it look professional though would be tough. A capacitve screen; if it behaves like my phone, i useless with a wet finger let alone being showered on.

I agree with the statement that it would be hard to differentiate a button press in the middle, but i'd put the icons in the centers of each quadrant.

like this:

| o | o |

| o | o |

Maybe the best option is to mock it up , and get raw reading and see if they differentiate enough to calculate a quadrant