solid state 02 sensor

[TecDivingBremen]

Hey,

I have a problem with my solid state 02 sensor. I bought it in 2024, together with my OSTC 4. I didn’t used it that much but now it’s shows a reading of 18% O2 in air.

Maybe someone can help.

Cheers
Sven

[swissdiving]

If you bought it from HW did you mail them and ask for support?

[TecDivingBremen]

No I didn’t do that by now. That would be the next step if no body has a idea

[mikeller]

Hi Sven.

Completely off topic, but it looks like you've got a pretty decent looking 3D printed protector on your OSTC4 - is the design for this publicly available?

Ngā mihi
Michael Keller

[Thorsten]

Hi Sven,

looks like you have connected the sensor directly to the OSTC? I think that does not work well because the OSTC4 output voltage does not match the needed input voltage of the sensor. The sensor responds but it is operated out of specification. HW offers a multiplexer board which takes care for the operation voltage. Alternativ would be to insert a shifter into cable but I think the best idea is to get in contact with HW regarding these hardware details.

Another remark regarding the sensor housing. The sensor is much more resistant against humidity than for example the common used CO2 sensors. But I had the case during winter operation and bad storage condition that after some time humidity gets to high during dive if the backside of the sensor is in contact with the breathing air. You can check the humidity in the sensor view before the dive and it shoud be in the range shown of the photo you posted. If its higher it is possible to get the humidity out again by storing in dry environment for some time.

I am using a sensor housing where the sensor front is sealed by the oring and on the back side I am using a membran for the pressure exchange which is needed.

By the way was the OSTC4 cover printed using a J1 (surface looks like J1 standard print bed) ;-)?

Cheers
Thorsten

[Peter51]

Hello,


I thought I had the same issue with my brandnew OSTC 5 with the Solid State O2 Sensor directly connected. The reading with air at ambient pressure was 0.17bar.

I contacted Heinrichs Weikamp and Matthias' answer was:

Hallo,

Die Sensoren sind für den relevanten Bereich um 1bar O2 werkskalibriert und weichen nach unten am meisten ab. Spüle mal mit 100%, dann müsstest Du bei Deinem Umgebungsdruck auf 0,97bar kommen. Der OSTC 5 liefert zuverlässig für bis zu 4 Sensoren ausreichend Spannung. Ein DC/DC Konverter ist nicht nötig. Auf der boot haben unsere Sensoren ebenfalls keine 21% gezeigt (Foto anbei). Der in unserem Demonstrator verbaute "Mulitplexer" hat auch keinen DC/DC verbaut gehabt.

Viele Grüße,
Matthias

English translation:

Hello,

The sensors are factory calibrated for the relevant range around 1 bar O2 and deviate most downward. Rinse with 100%, then you should reach 0.97 bar at your ambient pressure. The OSTC 5 reliably supplies sufficient voltage for up to 4 sensors. A DC/DC converter is not necessary. Our sensors also did not show 21% at boot (photo attached). The “multiplexer” installed in our demonstrator did not have a DC/DC converter either.

Best regards,
Matthias



With 100% O2 the reading at ambient pressure was 0.97bar. So everything is ok.

Regards,
Peter