Re: PID Mod for Silvias, Gaggias, etc
Hi again Craig,
Taking your questions in turn:
A1) This is ideal of course, as the fewer the number of temperature transition points there are, the better. That being said though, with such a small boiler it doesnt really matter all that much and brass/stainless steel, etc are very good conductors of heat so it would be acceptable to attach the t/c to the surface of the boiler. The simple answer being NO.
A2) Im not familiar with the physical characteristics of the boiler in your particular machine, but if it was possible to attach the t/c close to the position of the original Brew T/stat, thats what I would do. Apart from that, if you attached it relatively close to the discharge into the Brew Head then that would also be ok.
A3) Redundant
A4) Redundant
Hope that helps you out Craig. The parameter of concern with these sorts of decisions is the "time" it takes between a change in temp taking place and how long before that change is detected and acted upon. In large boilers this can be critical but in boilers with capacities less than half a litre and a relatively large Heating Element, it is of no real consequence. With this application, you can think of it as Thermal Intertia.
This time delay, if significant enough, can lead to instabilities in the temperature control which can result in large oscillations of the water temperature. In these type of situations, PID controllers really come into their own and especially those with Fuzzy Logic assistance.
The FL uses algorithms which interface with "rules" that attempt to replicate the way humans think and work, and can "learn" to cope with a wide range of differing operational circumstances and disturbances in the process. FL and Artificial Intelligence originated from similar beginnings and are kindred philosophies as a point of interest.
After all this, I hope I havent muddied the waters. There is a plethora of information about this kind of thing to be found on the Net and if you wanted to know more about it, this isnt a bad place to start
http://www.expertune.com/tutor.html
All the best,
Mal.
Hi again Craig,
Taking your questions in turn:
A1) This is ideal of course, as the fewer the number of temperature transition points there are, the better. That being said though, with such a small boiler it doesnt really matter all that much and brass/stainless steel, etc are very good conductors of heat so it would be acceptable to attach the t/c to the surface of the boiler. The simple answer being NO.
A2) Im not familiar with the physical characteristics of the boiler in your particular machine, but if it was possible to attach the t/c close to the position of the original Brew T/stat, thats what I would do. Apart from that, if you attached it relatively close to the discharge into the Brew Head then that would also be ok.
A3) Redundant
A4) Redundant
Hope that helps you out Craig. The parameter of concern with these sorts of decisions is the "time" it takes between a change in temp taking place and how long before that change is detected and acted upon. In large boilers this can be critical but in boilers with capacities less than half a litre and a relatively large Heating Element, it is of no real consequence. With this application, you can think of it as Thermal Intertia.
This time delay, if significant enough, can lead to instabilities in the temperature control which can result in large oscillations of the water temperature. In these type of situations, PID controllers really come into their own and especially those with Fuzzy Logic assistance.
The FL uses algorithms which interface with "rules" that attempt to replicate the way humans think and work, and can "learn" to cope with a wide range of differing operational circumstances and disturbances in the process. FL and Artificial Intelligence originated from similar beginnings and are kindred philosophies as a point of interest.
After all this, I hope I havent muddied the waters. There is a plethora of information about this kind of thing to be found on the Net and if you wanted to know more about it, this isnt a bad place to start
http://www.expertune.com/tutor.html
All the best,
Mal.


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