There are many opamps from which to chose. Can you tell us more about the characteristics of the sensor being used? You told us the output range is 1 to 100 mv over the range that you plan to use it. Do you have a datasheet or perhaps a part number that can be used to look up the specs for the sensor.

The o2 sensor is a Teledyne 22R. Here is some info from their website:

Regarding the R-22D sensor, what is the recommended calibration technique?
We recommend calibrating at the highest O2 level that the unit will be used at. At 100% O2, the output is about 5 times higher than at air (100/20.9 to be precise). Some sensors put out 10mV in air. Then these will put out 10mV*(100/20.9) in 100%. Some sensors put out 13mV in air. Then these sensors will put out 13mV * (100/20.9) in 100%. Please understand that these sensors are partial pressure O2 sensors. They respond to changes in the partial pressure of the O2 sample.

I am at least somewhat concerned about the suitability of using batteries as the power source for your project. The temperature range is my first concern. I don't know that batteries are going to hold up well at the temperature extremes you have mentioned. The other concern is the high pressure of 300 psi. I don't have any direct experience with the use of batteries in high pressure applications.

Understandably so, the batteries would not be subject to the high pressures, as thew would be sealed in a 1ATA compartment (similar to pressure not increasing inside a submarine). Is the temperature range really a factor for a typical 9V or AA Battery? I really don't know.

Thanks

Cheers

Mike

 

Here's more info on the sensor I was looking at using. One is a High output 33D, the other is Low output 22R.

Schematics are attached below.

Cheers

Mike

 

...

Understandably so, the batteries would not be subject to the high pressures, as thew would be sealed in a 1ATA compartment (similar to pressure not increasing inside a submarine). Is the temperature range really a factor for a typical 9V or AA Battery? I really don't know.
....

I did a little searching on the web and it looks like the typical temperature range for alkaline batteries is -4F to 130F. That could make things iffy on the low end of the temp range but since you are not expecting to subject the batteries to any significant temperature extremes then you should be safe.

You mentioned that you will be using an LCD display. Are you looking at a character-type display (i.e. 2 lines by 20 characters) or a graphic- display?

hgmjr

 

I did a little searching on the web and it looks like the typical temperature range for alkaline batteries is -4F to 130F. That could make things iffy on the low end of the temp range but since you are not expecting to subject the batteries to any significant temperature extremes then you should be safe.

You mentioned that you will be using an LCD display. Are you looking at a character-type display (i.e. 2 lines by 20 characters) or a graphic- display? hgmjr

I am open on this as well. Although a character type LCD would get the job done, a nice backlit graphic lcd with bitmap options would really look alot better. Although Battery life and voltage consumption could become an issue with the backlight. Anyone tried to use Oled's ? Does anyone know where to get them approx 4" x 2" ?

Cheers

Mike

 

I can't think of any more questions at the moment. I think you have divulged the primary parameters that you are looking for.

The next step is choose a microcontroller that you feel comfortable with. You seem to be leaning toward the BASIC stamp. I am sure that there are some members here in the forum that have had experience with this processor.

For details on BASIC stamp microcontroller design features, I am content to defer to those members with first-hand BASIC Stamp experience since I do not have any.

hgmjr

 

I can't think of any more questions at the moment. I think you have divulged the primary parameters that you are looking for.

The next step is choose a microcontroller that you feel comfortable with. You seem to be leaning toward the BASIC stamp. I am sure that there are some members here in the forum that have had experience with this processor.

For details on BASIC stamp microcontroller design features, I am content to defer to those members with first-hand BASIC Stamp experience since I do not have any.

hgmjr

Thank you very much with all your help, it has been greatly appreciated.

Have a great Holiday.

Cheers

Mike