Thanks for the advice Bill!

If you are using this on a 2 group you will only be able to use one group at a time.

Ive been thinking about this for a few days, Im assuming the only way around this is 2 separate brew boilers, each with a dedicated pump??

Sounds like it could be done on a 4 group with its 2 brew boilers.

Well my 2 Lineas arrive on wednesday, PID has been ordered along with other bits & pieces, so will be able to get started straight away.

If I use a Scace device to calculate margin of error & to calibrate the pressure profiling system once installed, I figure I can use a high sensitivity pressure transducer mounted in the boiler between the group heads.

From what I remember of hydraulics, I think that the pressure at the brew boiler should be very close to what is at the group head???
Or should I be fitting a pressure transducer to each group head for more accurate readings?

The analog output of the pressure transducer can be fed to an AD converter which in turn feeds digital data to my computer.
Using software I can enter the margin of error of the transducer based on the data from the Scace device & output that to a digital readout mounted on the front of the machine.

Using temp transducers mounted in each group head & AD converters, I can also do the temp calibration with the Scace device & enter margin of error as well.

Well I found some thermometers with an output that I can send to a microcontroller. SYL-1812XA
I also found some RTD pipe plug probes with 1/4" & 1/8" NPT fittings. The probes only stick out about 1/2" so I should be able to mount them in the gooseneck very close to the group head.

Currently looking for a decent pressure transducer with a update maybe every 250mS.
Can anyone tell me if I need the pressure transducer very close to the group head or can I get away with having it between the group heads, on the brew boiler??

OK, the placement of the pressure transducer is of great concern. i am glad you are having this discussion. Everytime the water passes through an orifice or goes through a tube there is some pressure loss. If the orifice is small enough it can cause some dampening effect (or delay reaction). This is why it is important to have the transducer as close to the brew head as possible. I can't remember if you are using the group caps that have the flow meter and valve attached or not. If not then the best and easiest place to mount the pressure transducer is just before the 3 way valve. After the valve would even be better but you run the risk of coffee grounds in the transducer. If you are using the group cap with the valve attached then you can drill into the valve and mount it there.

For the 2 group you would need separate boilers for this. You could use 2 GS3 boilers. This is the method LM will use for the Strada and also has started on some other machines for the past year or so. Also with a bit of circuitry you should be able to use the standard LM probe or any other with a microcontroller. What brand of microcontroller are you using?


Bill

Thanks for your advice Bill!

Ive been shopping around for pressure transducers & Im starting to think I would be better off getting a Scace II device to tune the PWM outputs to the motor & displaying the pressure as a function of pump voltage.
Unless anyone can suggest a source for inline pressure transducers (I was thinking of measuring the pressure before the pump, as well as at the group heads
I would save some money & I could use it to set up the 2nd machine as well, for no extra cost.

Machines are supposed to be arriving today, so will be able to tell you about the group head valves & flowmeters hopefully soon.

I figure that Ill do it as a single boiler version first, which gives me time to source some GS3 boilers (have emailed espressoliquidators & marzoccoman).

Im planning on using an Arduino Mega board. Lots of I/O, multiple PWM outputs that I can amplify for gear pumps. Ill build a prototype on breadboard first then etch some PCB's once tested & working. I would like to connect it to a 128 x 64 LCD, so I can display extraction time, group head temp, pressure & a graphic of the pressure curve selected. Also I will use a pot for an analog input to help initially tune the system & to do manual pressure control as well.

So, the hydraulics & solenoids are all assembled in the first machine (Thanks Todd for doing the cleaning for me!)
So Ill have to find myself a 220V supply soon so I can test if solenoids operate before I attach the original wiring harness.
Once I have a operating machine, I can start the modification process.
Heres a pic of the machine so far.....

Almost finished fitting the electronics.
Im using the original wiring harness, however I am replacing all crimp connectors.

Big thanks to Bill for sending me a wiring diagram to help me figure out where everything went!

Heres a pic of the machine at the moment

Sweet.

Dunno why I haven't been following this thread closely, but I have a few cents to toss into the hat.

First, I notice that your fb80 has Pierro group caps. Putting them on your Linea has a LOT of bang for the buck, and would be my first choice in Linea mods over pressure profiling. The mod is particularly effective on AV Lineas because the group solenoids and flowmeters are unheated in the stock configuration, which means that the Lineas need big heating flushes when used in intermittent duty. Installing the Pierro caps gives the Linea +- 0.5 degree stability in all duty cycles - on the order of the GS3. The caps from LM are only for the welded groups, but I believe that Terry's folks at EPNW have a retrofit kit that allows you to put them on the old style groups.

Second - if you are intending to develop a profiling system for commercial service I suggest that you talk the the LM guys a lot. They have been working on alternatives to the TMFR that might be easily integrated into the Linea. Ask yourself the purpose of your project. If it's to learn a little about pressure profiling, then the path that Nicholas took (manual control of the TMFR pump) is a relatively cheap way out. If you are looking to develop a robust system that can operate in the commercial realm, then you should defer to existing equipment (LM) if possible. It's certainly possible to design and build your own automated and programmable system, but it's a pretty big project for a home guy, and when it fails in the commercial environment you're gonna have to be able to provide support pronto since livelihoods are on the line. That's very different from the home scene, in which a broken machine is merely an inconvenience.

PM me with specific questions if you wanna.

-Greg

Hi Greg!,
Thanks for your input, Im honored to have 2 of the biggest hitters in the game weighing in on my thread!

I figure I will be doing the mods in stages & testing the machine in a commercial environment (my work) & having the work fb/70 as a backup in case.
I plan to do the mods in a few stages.
Currently the first one is the brew boiler PID (since the original brew boiler thermostat was damaged during removal).

Im wondering with the Piero caps mod, since I will be later replacing a lot (possibly all) of the control systems, if it is worthwhile converting the machine to an EE & doing the EE piero cap mod (Im assuming I will need EE group heads?)

Also as I want to install a pressure profile system, I intend having a failsafe system in place.
I figure that since a gear pump can run on either a PWM or varying voltage, I can run the microcontrolled profile system in parallel with a basic potentiometer controlled system, that I can set the pump pressure on & simply have inline switches on each system. So if the microcontrolled system fails, I can switch it off & switch on the basic system, adjust my pressure via the potentiometer if necessary & continue operating the machine.

Later on down the line, Im thinking of possibly using 2 gs/3 boilers ( 1 for each group) & running 2 PID controllers with separate profiling systems to use different coffees on the same machine, but thats a fair time away!

The rebuild part of the process is almost complete. Just need to get a replacement pump cable (the insulation on the old one was falling apart), also waiting for some silicon wire for the solid state relay & a project box for the pid to arrive in the mail.
I found a significantly cheaper waterproof enclosure for the pid unit. Only catch is I have to cut the hole in the front, but $5.76 instead of $80 works for me.
So here is a couple of pics