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
solid state 02 sensor
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TecDivingBremen
- Posts: 2
- Joined: Wednesday 11. June 2025, 03:05
solid state 02 sensor
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swissdiving
- Posts: 838
- Joined: Saturday 30. July 2011, 07:30
Re: solid state 02 sensor
If you bought it from HW did you mail them and ask for support?
Cheers,
Hansjoerg
--> 2N - 2201 / 3892
--> OSTC4 - 257 / 392 / 424 / 1324 Fischer
--> OSTC5 - 1507 S8
RTFM
Hansjoerg
--> 2N - 2201 / 3892
--> OSTC4 - 257 / 392 / 424 / 1324 Fischer
--> OSTC5 - 1507 S8
RTFM
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TecDivingBremen
- Posts: 2
- Joined: Wednesday 11. June 2025, 03:05
Re: solid state 02 sensor
No I didn’t do that by now. That would be the next step if no body has a idea 
Re: solid state 02 sensor
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
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
Re: solid state 02 sensor
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
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