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Bluetooth Pressure Gauge for the Sage/Breville Barista Express.

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  • Bluetooth Pressure Gauge for the Sage/Breville Barista Express.

    Hello Everyone!

    I was thinking about replacing the pressure gauge on the Barista Express with a Bluetooth Pressure Transducer and writing an iPhone App for it.

    Does anybody know the connection type for the pressure gauge (NPT/BSP etc.) ?
    What is the numeric range equivalent for the original gauge output ?


    Thanx in Advance!

  • #2
    150psi would just cover it. 175psi would be better.
    You will probably want to T into a pressure pipe somewhere, so thread doesnt really matter as you will be welding fittings to suit your application

    Comment


    • #3
      The gauge in the 6910 looks about 1/8

      Comment


      • #4
        I was thinking 200psi (20 bar) for the transducer, there are several alternatives out there like the M5600 from TE Connectivity.
        With that device it would be plug and play, just need to write the software, as long as the connector fits.

        My initial thought was to "replace" the pressure gauge with the transducer.
        That is "digitise" the output from the analog pressure gauge.

        Doesn't the outlet for the front pressure gauge reflect the "brew pressure" ...
        and the water temperature close to what the temperature is at the group head?

        Comment


        • #5
          M5600 comes in every thread imaginable. They also run off a button cell battery so no need for power. Downside is 5 sec sample rate. Maybe can change that?
          So it outputs to a app that graphs the result.

          $245 makes this a pretty big investment. Pretty cool too!!

          Comment


          • #6
            I dont know your other answers.
            Pop the covers on your machine, and check it out yourself.
            I would think you are best to put the transducer not at the end of the little thin coil of tube, although that would reduce the temperature that it sees and allow mounting flexibility.

            Comment


            • #7
              Originally posted by Jackster View Post
              M5600 comes in every thread imaginable. They also run off a button cell battery so no need for power. Downside is 5 sec sample rate. Maybe can change that?
              So it outputs to a app that graphs the result.

              $245 makes this a pretty big investment. Pretty cool too!!
              The sample rate can be adjusted down to 100 ms via software, however it will eat up the battery.
              The workaround is to implement pressure change detection (and phone proximity) and ramp up the sampling during extraction
              and than reset to standby when done.

              And the pressure change could also be used for starting and stoping a "shot timer".

              Here in Sweden it's more like 190 USD... the good thing is that it can easily be moved to any machine
              with a bit of "plumbing" and can even be used on a portafilter with an adapter...

              Actually waiting for some answers from a TE Connectivity Rep. cause according to the data sheet the operating temperature is max 85C
              and the compensated temperature range is only up to 60C, so depending on what the Total Error Band is at 100C it might not be suitable for this application.

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              • #8
                Well use the coiled thin wire. That will reduce the temperature considerably.

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                • #9
                  Progress in the project... went the DIY route not the M5600.


                  I will use a the following parts:


                  - SiLabs BLE112 Bluetooth Module
                  - Honeywell PX3 Series Pressure Sensor
                  - TI LM35DT Temperature Sensor


                  By using the BLE112 module and making a custom circuit board,
                  costs are greatly reduced and the modular design makes it easy to
                  use whatever sensors one have or can afford.

                  Comment


                  • #10


                    Under the hood in the Barista Express... (before the modification)

                    Comment


                    • #11
                      The pump over pressure valve in this machine only operates as a safety valve (opens at a set point to prevent pump or machine damage) rather than a traditional OPV (opens at a set point to regulate pressure within a set range).

                      There is no benefit in knowing the pump pressure in this machine. You could install an OPV from a Breville Dual Boiler but this won't make a whole lot of difference to the in-cup taste. I've tried it before and it's not worth the effort for such little result.

                      It's a cool project though and certainly could be of benefit in other machines in the future.

                      Comment


                      • #12
                        Originally posted by noidle22 View Post
                        The pump over pressure valve in this machine only operates as a safety valve (opens at a set point to prevent pump or machine damage) rather than a traditional OPV (opens at a set point to regulate pressure within a set range).

                        There is no benefit in knowing the pump pressure in this machine. You could install an OPV from a Breville Dual Boiler but this won't make a whole lot of difference to the in-cup taste. I've tried it before and it's not worth the effort for such little result.

                        It's a cool project though and certainly could be of benefit in other machines in the future.
                        Well, there is a pressure gauge on this machine, the outlet for this gauge sits on the top of the group head.
                        Correct me if I'm wrong but my understanding is that by digitising that pressure one would get the actual "brew" pressure ?

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                        • #13
                          Yes, you get brew pressure on the gauge. But it is only regulated by the grinds. If its like the 6910 and 6900 i think it will just stall out at max pump pressure. There is a bypass thing on the output of the pump, but on inspection its a vacuum breaker, not a pressure relief.
                          So a opv will regulate pressure at its setting, and then drop as the puck wets out.
                          Without the opv, its only the resistance of the puck regulating the pressure. Even if you know the pressure, you cannot change it other than by the grind.

                          You could set up pressure profiling though...use the pressure gauge to regulate the pump. Maybe pid the pump?

                          Comment


                          • #14
                            Done with the first revision of the PCB for the sensor module. Will send it to the fab. house next week.
                            Pretty happy with the size 30 x 45 mm so it fits perfectly in a Hammond 1551 plastic enclosure.

                            Click image for larger version

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                            • #15
                              Originally posted by Jackster View Post
                              Yes, you get brew pressure on the gauge. But it is only regulated by the grinds. If its like the 6910 and 6900 i think it will just stall out at max pump pressure. There is a bypass thing on the output of the pump, but on inspection its a vacuum breaker, not a pressure relief.
                              So a opv will regulate pressure at its setting, and then drop as the puck wets out.
                              Without the opv, its only the resistance of the puck regulating the pressure. Even if you know the pressure, you cannot change it other than by the grind.

                              You could set up pressure profiling though...use the pressure gauge to regulate the pump. Maybe pid the pump?
                              Maybe, but for that I really need to take the machine apart to see what is possible to do.

                              Comment

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