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Hey guyz!,
I am using a differential pressure sensor(SX100DN) from honeywell...http://www.digchip.com/datasheets/parts/datasheet/1749/SX100DN.php.... its output voltage is 100-150mV...i wanted to connect it to the analog input of duemelinove.... Is it necessary to use an amplifier or is there any alternate method?....
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You can use the internal 1.1V analog reference and measure 1024 steps between 0 mV and 1100 mV.

If you need finer resolution you will need an amplifier.
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thanks!...how do i do it?...i am new to arduino!!
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You can use the internal 1.1V analog reference and measure 1024 steps between 0 mV and 1100 mV.

If you need finer resolution you will need an amplifier.

Even using that lowest 1.1vdc reference voltage, one would still only get 10% of the measurement range of the analog input pin (so 100 'counts' of measurement range). I suspect you would be very dissapointed at the resulting resolution and noise variation that would result of using that method.

This kind of basic sensor is really designed to use with an input Wheatstone bridge compatible op-amp to increase the measurement output voltage to something more useful.

Lefty
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can you please suggest any opamp... as in the model no. or something?!
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can you please suggest any opamp... as in the model no. or something?!

In theory virtually any opamp(s) can be used, as it's not so much the specific opamp used, but rather the circuit it's used in. There are opamps that are optimized for use in low level bridge circuits, but first you are better off understanding the basics of interfacing with low level bridge type devices. This seems to be a useful article to start off with:

http://www.ti.com/lit/an/sloa034/sloa034.pdf

Lefty
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Thanx!!...smiley-grin
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WARNING: The output is not 100mV ... 150mV. It is a bridge sensor. The 100mV ... 150mV is the difference between the output pins. Since the sensor needs 12V the output pins are near 6V, and this is too high for the Arduino.

ADVICE: Buy an other pressure sensor. Look at the sites of Sparkfun and Adafruit to see what kind of pressure sensors can be used with the Arduino. You first have to know if you want a baromic, absolute pressure sensor or a relative pressure sensor.

OPAMP: If you want to use this sensor, you have to use an opamp. But you have to use a good regulated 12V for the sensor and a good 5V for the Arduino. Opamps like the INA128 can be used as opamp. I think they operate at a low voltage like 5V and allow the inputs to be a higher voltage.

This is a simular pressure sensor : http://playground.arduino.cc/Main/SPX3058D
That pressure sensor uses 5V, which is okay for the Arduino. By connecting it directly to the Arduino inputs, the calculated pressure is very inaccurate. But the sensor was inaccurate anyway, so it was still usable for me.
« Last Edit: February 14, 2013, 07:25:54 am by Krodal » Logged

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Thanks a lot!!....smiley-grin
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