From: pcdhSpamMeSenseless@electrooptical.net   
      
   Jeroen Belleman  wrote:   
   > On 12/27/25 01:35, Phil Hobbs wrote:   
   >> Jeroen Belleman  wrote:   
   >>> On 12/26/25 11:37, Don Y wrote:   
   >>>> On 12/26/2025 3:27 AM, Liz Tuddenham wrote:   
   >>>>> Don Y  wrote:   
   >>>>>   
   >>>>>> Any pointers regarding deployment of pressure sensors measuring   
   >>>>>> air pressure?� I'm looking at nominally an inch of water   
   >>>>>> (pressure/vacuum)...   
   >>>>>   
   >>>>> Washing machine/diswasher water-level switches?   
   >>>>   
   >>>> No, I'm looking at pressures in air handling systems.   
   >>>>   
   >>>> In systems that I've designed previously, someone   
   >>>> else selected (very expensive!) transducers and   
   >>>> I just had to interface with them.   
   >>>>   
   >>>> But, those were industrial systems with dedicated   
   >>>> staff to keep them running, calibrated, etc.� You   
   >>>> cared about the actual "numbers" from the sensors   
   >>>> because you were controlling "regulated" processes   
   >>>> and needed to document compliance/exceptions.   
   >>>>   
   >>>> I'm trying to leverage some of those algorithms but in a   
   >>>> cheaper consumer market where stuff "just has to work".   
   >>>> I don't care about numbers as much as *trends*, using   
   >>>> adaptive algorithms to sort out what's "normal" from   
   >>>> "indicating".   
   >>>>   
   >>>   
   >>> I've had some fun with teeny tiny BME280 sensors. They   
   >>> have a sub-1% absolute accuracy and enough resolution   
   >>> to detect the pressure change between your head and your   
   >>> feet. They measure temperature and humidity too. The   
   >>> interface is I2C.   
   >>>   
   >>> Jeroen Belleman   
   >>>   
   >>   
   >> Of course they might be detecting the difference in the mean molecular   
   >> weight of the local atmosphere. ;)   
   >>   
   >> Cheers   
   >>   
   >> Phil Hobbs   
   >>   
   >>   
   >   
   > Grmpf ;-)   
   >   
   > While I was graphing the outputs, I was surprised by the efficiency   
   > of humidity readings to detect human presence. The curve was quite   
   > smooth with no one in the room, but got quite noisy with someone   
   > present.   
   >   
   > jeroen Belleman   
   >   
      
   We’ve used the very nice Sensirion SHTC3 (“schtick #3?”) T/H sensor to   
   calculate the dew point to monitor desiccant performance and prevent   
   condensation. Super good medicine.   
      
   Cheers   
      
   Phil Hobbs   
   “Three French hens….”   
      
   --   
   Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /   
   Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)