Connecting Oxygen Sensor to Axon II

[codiak]

I'm looking for the best way to connect a Teledyne R22D Oxy Sensor to the Axon II.

The sensor datasheet can be found http://www.globalspec.com/datasheets/15/TeledyneInstruments/F989C301-0E35-4889-8E7F-EE4C2A94C761

Short version:
    In the presence of Oxygen the sensor generates a current between 0-100 millivolts based on pressure and percent of O2 present.

Is leaving the reference voltage at 5v and using op amp with a gain of 50x the right way to approach this?
  If so: any recommendations of op-amp vendor?

Is there a better way to go about this?

Thanks!

[Admin]

Hmmmmm thats not a link to a datasheet, and I'm not signing up for an account with them

generates a current between 0-100 millivolts

A voltage or a current?

If voltage, then yes, you should use an op-amp. Op-amps tend to not be so accurate after around 20x amplification, so check the datasheets. You can always use more than one op-amp in series.

I recommend just powering up the sensor and using a voltage meter first to see what voltages you get, that way you'll know better of what kind of amplification you'd need.

[waltr]

Hmmmmm thats not a link to a datasheet, and I'm not signing up for an account with them

Same here....

[codiak]

Hmmmmm thats not a link to a datasheet, and I'm not signing up for an account with them

generates a current between 0-100 millivolts

A voltage or a current?

If voltage, then yes, you should use an op-amp. Op-amps tend to not be so accurate after around 20x amplification, so check the datasheets. You can always use more than one op-amp in series.

I recommend just powering up the sensor and using a voltage meter first to see what voltages you get, that way you'll know better of what kind of amplification you'd need.

Don't blame you... though I didn't find an alternate...

regardless, it is in millivolts and is voltage... so Op-amp it is.

[Soeren]

Hi,

[...] Op-amps tend to not be so accurate after around 20x amplification, so check the datasheets.

That statement is valid when you are scraping upon either the gain-bandwidth product or the slew rate. At near DC, as an oxygen sensor output is, there shouldn't be any problem with a current rail-rail amplifier.

codiak <- According to several divers sites, this particular sensor has an output stated as +/-10mV, not the 0..100mV stated by you.
Not sure of the +/-part though, but perhaps it can detect antimatter, or at least anti-oxygen   


If it is for anything health-critical, I'd advice against homemade gizmos lacking Quality Assurance!

[codiak]

codiak <- According to several divers sites, this particular sensor has an output stated as +/-10mV, not the 0..100mV stated by you.
Not sure of the +/-part though, but perhaps it can detect antimatter, or at least anti-oxygen   

+- is the warning that results will vary... the device will decay over time

+/-10mV is what a fresh sensor will read 20.9% O2 (IE Air) at Sea-Level....
mV will increase as percent of 02 or ATM pressure increases and is linear in nature.
100% 02 =~ 55mV
100% 02 at 2 Bar =~ 95mV

Meters using these sensors need to be recalibrated with a known/trusted air supply prior to use.

If it is for anything health-critical, I'd advice against homemade gizmos lacking Quality Assurance!

I'll be sure the lawyers are the first users... ;-)

For my purposes it's not in the critical loop

[Soeren]

Hi,

Meters using these sensors need to be recalibrated with a known/trusted air supply prior to use.

Ah, then long term stability is not a priority - blasted sensors, not manufactured anymore and with a 3 year lifespan.

I seem to recall something about a guy experimenting with using zinc/air cells for oxygen sensors with pretty good results, although they needed recalibration now and then as well - but a zinc/air cell is cheap, the RD sensor is not.
Don't recall if he researched it for diving purposes though.
Maybe a quick Googling will get you there, if you are interested.
 

I'll be sure the lawyers are the first users... ;-)

For my purposes it's not in the critical loop

I was more concerned about the implications of you diving in with a bunch of loose wires