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Author Topic: sensor box using a single analog input  (Read 874 times)
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argentina
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hi, i'm not sure if this is the right board, but i thought some of you might have had this worked out and could point me out to the solution.
I'm building a garduino project, and i wanted to take a measurement to many different pots to analyze better the data. The problem is, i have only so many analog ports, and i don't really think a bigger chip is quite worth it since the measurements don't need to be simultaneous.
I thought about this circuit using npn transistors as switches. would my measurements be affected by the other sensors?
i put the transistors in between the supply and the sensors because prolonged powering of the sensors builds up rust and what not, i'd prefer to use them when i read them and no more. Do you think i should add a couple transistors after the sensors too to isolate the measurements?
thanks.
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argentina
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woopsie i forgot the schematics.
the circles are meant to be the connections to the arduino. the leftmost circles are the digital pins and the rightmost circle is where i plan to plug the analog pin.
oh yea, and i want  to measure the values of R3 and R4.


* schem.png (13.99 KB, 755x477 - viewed 21 times.)
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argentina
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bump..
moving the thread to sensor board
http://arduino.cc/forum/index.php/topic,129979.0.html
i think that board is more appropiate. please answer there
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New River, Arizona
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Funny how the experts haven't chimed in here.  There are some folks on here that could really help you with this.  Maybe if I say something stupid they will chime in with a correct answer to help you out.

Here's a person that had the same problem and how he solved it.  Could be much cheaper and easier than other methods

http://miscellanea.com/how-to-get-more-arduino-analog-inputs/

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argentina
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hmm. that sounds like a good option.
i'll check on that IC and hopefully i can buy it where i live. it's probably gonna end up being cheaper than buying one transistor for each analog.
it would be nice tho to know how to build this without using an IC. i don't know why but i'm sure there is a way to do it.
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