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I was wandering if there is any such sensor, that would read pressure, temperature or moisture ( approximately 12 inch long strip)? I want to be able to dip this sensor into water and have it be able to give me a reading of how much of the sensor is under water out of the total length of the sensor? So essentially I need a sensor that can take many readings along it's length telling me at each whether it is above water or below water by using any of the above methods.

If possible I would like for it to be able to adjust on the fly as well. I don't want to have to dry it off every time a depth changes.

Is this possible? Do you know of any place I could buy something like this?

Edit: Thanks for the input guys. I found this : http://www.milonetech.com/Purchase_eTape.html Do you think that will work with the accuracy I need? I think it would be easier to buy something like this than build it, but I may be wrong. Please tell me what you think. Thanks.

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  • \$\begingroup\$ There are various options you could use: two pressure sensors, a capacitive sensor, an acoustic (US-reflexion) sensor, a floating magnet and a set of reed switches, etc, etc. Choice depends on accuracy, repeatability, price sensitivity, logelivity, etc. \$\endgroup\$ – Wouter van Ooijen Aug 10 '12 at 16:20
  • \$\begingroup\$ Okay thanks. Which of the above methods do you think could be used reliably over and over again. I would like it to be as accurate as possible, but somewhere between 1 and .5 mm would be acceptable. Are any of these options viable for this at a reasonable price? If so, where would be the best place to buy such a sensor? Thanks so much for your help thus far! \$\endgroup\$ – Sam Aug 10 '12 at 19:31
  • \$\begingroup\$ Why the two user accounts? It's being frowned upon, and only leads to confusion. \$\endgroup\$ – stevenvh Aug 12 '12 at 12:50
  • \$\begingroup\$ @Sam (I don't know which one :-)) - You didn't register. If you're registered you should always automatically login with the same account, I think. One thing with the two accounts is that you can't even edit your own posts without approval. Because they're not Sam's, but those of Sam, if you know what I mean :-). \$\endgroup\$ – stevenvh Aug 12 '12 at 13:19
  • \$\begingroup\$ @Sam I merged your accounts, they are currently "unregistered accounts" and tied to your cookies on your computer, if you register with an OPENID you will fix that issue completely. If you end up with multiple accounts in this way though you can flag a post of your other account and a moderator can perform a merge for you :) \$\endgroup\$ – Kortuk Aug 12 '12 at 13:34
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I would suggest trying a capacitive sensor. They can be constructed many ways. Google for "capacitive water level" and you'll get a bunch of hits that are relevant. Not sure if you'll be able to build one that is sensitive enough for your needs, but it's a place to start.

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The water level sensor that I am currently using is found here: http://vegetronix.com/Products/AquaPlumb.

So far, it seems to have been working well - it works in both salt and fresh - and it hasn't corroded yet. It is able to tell me exactly what depth the water is and it is pretty easy to operate. However, it is about 2 times the cost of the e-tape. I am looking for more water level sensors, but I need to maintain the accuracy.

I'm interested in hearing about how the e-tape works: I've been looking at it myself because of its relatively cheap cost, but haven't been sure whether it really works or if it is more of a novelty item. Hope you found this helpful, and I'd love to hear how the e-tape is working!

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  • \$\begingroup\$ Welcome to EE.SE. You post does have an answer component, which is good. But it also have a secondary question component. The space under the original question is reserved for answers. So, be careful with secondary questions. In time, you'll earn enough reputation, and you'll be able to post comments and ask secondary questions in the comments. Of course, you can also ask a brand new question (i.e. start a new thread) and reference this thread. \$\endgroup\$ – Nick Alexeev Jul 15 '14 at 17:34

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