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cstmwrks · 8th October 2006, 02:29

Quote: (Originally Posted by teknosofen)

Hi Bill!

So you have refound the old thread, the sensors I sent you might have dried out by now but you can test them anyway.

In a way it is a resistance measurement, the principle is that you apply a polarisation voltage (ca 0,6V in the platinum sensors you got) and then the resulting current will be proportional to the PO2 (or rather the flow of O2 through the membrane which will be dependent on temp and PO2)

The current will be very low, << microamps but will depend on the design of the cell.

If you really want to get it started, I might be able to dig out the theory and practical papers for you.

As mentioned earlier, the old (but good) electrolung schematic is a good start.

Regards // Åke

Hi Ake,
The fog is slowly leaving my brain. I do have the patent drawings and now remember trying to figure out the value and type of thermister that was used in the sensor. There was the basic "r" value and the question of did it increase or decrease the R value with an increase in ambiant temp. I had a part number as I recall but could never get a cross ref to anything new. I know one can figure out what you need by building one and testing it but I wanted all the basic details of the original one. I had hoped that John Kanwisher would be kind enough to drop some details but I imagine I fell in the " if you have to ask how" then you should not do it catagory. So much for the short cut!

Bill

8th October 2006, 02:29	#13 (permalink)
cstmwrks The old ways still work. Current Rebreather/s: Home Build Other Rebreather/s: Not Bought Yet Home Build Join Date: Sep 2006 Location: Boise Idaho Posts: 244	Re: DIY 02 sensor Quote: (Originally Posted by teknosofen) Hi Bill! So you have refound the old thread, the sensors I sent you might have dried out by now but you can test them anyway. In a way it is a resistance measurement, the principle is that you apply a polarisation voltage (ca 0,6V in the platinum sensors you got) and then the resulting current will be proportional to the PO2 (or rather the flow of O2 through the membrane which will be dependent on temp and PO2) The current will be very low, << microamps but will depend on the design of the cell. If you really want to get it started, I might be able to dig out the theory and practical papers for you. As mentioned earlier, the old (but good) electrolung schematic is a good start. Regards // Åke Hi Ake, The fog is slowly leaving my brain. I do have the patent drawings and now remember trying to figure out the value and type of thermister that was used in the sensor. There was the basic "r" value and the question of did it increase or decrease the R value with an increase in ambiant temp. I had a part number as I recall but could never get a cross ref to anything new. I know one can figure out what you need by building one and testing it but I wanted all the basic details of the original one. I had hoped that John Kanwisher would be kind enough to drop some details but I imagine I fell in the " if you have to ask how" then you should not do it catagory. So much for the short cut! Bill Last edited by cstmwrks : 8th October 2006 at 04:58.
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