Oxygen Sensor

Hello,

i am not so confirm with electronic but i would like to connect a oxygen sensor to an arduino to messure the oxygen concentration in my office.

so the analog oxygen sensor generate a voltage of 0mv to ca 50mv on 100% oxygen.

Who i can connect this to the analog or digital arduino pin? i think i must work with an opto-coupler and i must a little bit stabilze the voltage from the sensor. i hope that its correct.

can anybody help me?

regards and sorry for my bad english Thomas

Why do you think you need an opto coupler? Is it because you need isolation between the sensor and the Arduino? Opto coupling a 50mv analog signal is not possible, you would need to amplify it and digitise it first.

If you don't need isolation, then from what you have said it sounds like the simplest approach would be to connect the sensor to an analog input, call analogReference to select the 1.1v bandgap reference, and read the pin. The reading will vary from 0 at 0% oxygen to around 40 at 100% oxygen. So you can read the concentration in steps of about 2.5%. If you need better resolution than this, you will need to amplify the output of the sensor with an op amp.

For more detailed advice, post a link to the datasheet for the sensor.

Hi

The for your fast respose. The resulution of 2.5 % is Not that what i want. I Need a Vetter resulution

I Hope that documenta will help

http://sumatec.de/produkte/sensor/scuba/D01.txt

But i Look for a Vetter datasheet

Here is a schematic of the circuit I suggest. The op amp needs to have an input common mode voltage that includes ground. It should also have a low input bias current. LM324 is probably OK but lower input bias current might be better. I’ve chosen to amplify the signal by a factor of 11, so the output may be up to 2.2v in pure N2 and about 0.55v greater in 100% oxygen.

If you are intending to use this in a diving application, be very careful. You need to evaluate the possible failure modes of the system and the hazard they may present to the user. For example, the processor could lock up, leaving the display frozen at its last value, when the oxygen is actually running out.

diving … interesting :wink:

don’t worry. i have enought monitoring devices. it’s only for learning technic deeper

Hi DC42,

thx for the grafic but it works not so as i think that it should wolk. can you give me a little introduction about the calculation for this mini setup?

thanks Thomas

See the "Non inverting amplifier" section in http://en.wikipedia.org/wiki/Operational_amplifier_applications. I forgot to mention that the +ve side of your sensor goes to the op amp input and the -ve side to ground.

thanks, that's works :) yesterday it was to late in the evening.