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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Wed Aug 28, 2013, 8:50am
Subject: Response time matters
 

Just to demonstrate how a poor measurement system can influence presentation, here is the same data I posted yesterday (minus some early time points) with some simple filtering applied.  Now it looks very much like graphs I've seen elsewhere - rise time is about 5 seconds, the bump is gone.   Deceivingly close to perfect (note: flat is not the goal).

First you need to identify/measure something, then you need to control/remove it and only then can you prove or disprove that it effects taste.

jonr: graph2.png
(Click for larger image)
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Wed Aug 28, 2013, 10:36am
Subject: the 3 second bump
 

Interesting, a cold portafilter had almost no effect but a 1 second flush 8 seconds before brew completely eliminated the bump.   It may be caused by steam being created in the brief period after the 3-way valve opens and before the pump comes up to pressure.
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,870
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Sat Aug 31, 2013, 10:15am
Subject: Re: Computer controlled boiler temp - better than PID?
 

Jonr, you posted on the Gaggia PID SBDU thread

"I don't know any programming language so I have to stick to analog. -Withildb  said

I don't know any program language so I used PID- I responded to Witholdb

Or you can run code that someone else wrote (say like mine).  Then it's much like running the pre-programmed PID units." -Jonr

I like PID because it is fairly simple to use and explain, and in that sense seems "better that computer."  :)  I understand many advantages of the computer board as you have explained in the thread.  

Can you make a "computer board for dummies" thread or posts here, so that I could go to the internet, or store(s) and buy proper supplies, connect them, and then install/run code and then install that on my machine and use it.  In addition, note how to change parameters such as delays and temperatures to tweak for flow, or for final volume.  Also include a display and box/housing recommendations.  Please write the instructions and install so that "it's much like running the pre-programmed PID units."  When I was setting up the PID system, I actually considered the Arduino and corresponded with one of past PID now Arduino users.  It was my impression that Arduino speak is much like foreign language, or at least its own technospeak.  I know that code written by others can be used if one knows how to, but I still do not see any instructions similar to PID.  I started with no PID knowledge and could understand enough from reading to use it. Can you make the computer system more user friendly?

 
D4F also at
http://www.gaggiausersgroup.com/
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Sat Aug 31, 2013, 4:55pm
Subject: Re: Computer controlled boiler temp - no programming needed
 

The key point is that you don't need to know programming to load and run someone else's code.

If someone wants to try my code, I'm willing to help and take notes as to what the non obvious issues are.  Most Gaggia Classic users wouldn't want to change more than a couple of well commented lines.  Basic system issues, like how to load a program, are well documented and discussed elsewhere at www.mbed.org.  At $20 the downside risk of not being able to get it to work is quite limited.

On the other hand, if a comment such as "verify that the sensor is reading around 1000 ohms" makes absolutely no sense, then a computer and my explanations are probably not a good fit.  I agree that an off  the shelf PID controller is simpler.

Of course perhaps 99.9% of users don't want to make any modifications.
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Sun Sep 1, 2013, 2:06pm
Subject: Pump control
 

Pump control (using an IGBT) is installed and working.  Not sure exactly how I am going to use it.  I'll start with slow ramp up of pressure.
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Thu Sep 5, 2013, 2:57pm
Subject: Re: Pump control
 

Initial taste results from a slow pressure ramp up are quite promising.  

I wired things to allow the computer to control the pump, but the 3-way valve is still manual.  This allows applying a little bit of pump pressure before the 3 way valve opens and this has completely eliminated the "steam bump" that I was getting at the beginning of the temp profiles.

Next step is to try a computer connected scale under the cup to get feedback on shot volume and flow profile.
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Sun Sep 22, 2013, 9:05pm
Subject: Re: Pump control
 

I switched back to just pre-brew temp control (+ some steam switch) for a week and definitely did not like the results as well as with brew-time heat control and a slow ramp of pump pressure (similar to pre-infusion).  

The scale project (to allow accurate flow profiling) is moving along.
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D4F
Senior Member


Joined: 15 Mar 2012
Posts: 1,870
Location: USA
Expertise: I like coffee

Espresso: Gaggia Classic PID
Grinder: Preciso
Posted Sun Sep 22, 2013, 9:16pm
Subject: Re: Computer controlled boiler temp
 

If I understand, you would have computer controlled idle, and then about 3 - 4 seconds of steam switch and then 3 - 4 seconds of rest, then the shot.  For comparison, like a standard PID configuration. What set temperature, and what did the boiler top temperature do during the shot?  A good comparator to those who would try PID or computer without added brew heat.  Of course you already mentioned the cup/taste.

 
D4F also at
http://www.gaggiausersgroup.com/
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Mon Sep 23, 2013, 7:29am
Subject: Re: Computer controlled boiler temp
 

I have a huge amount of flexibility wrt temp profile (shape and values) during brew and while I am using a profile that works better than what I was able to achieve with the steam switch, I'm certain it isn't optimal.   Perhaps as more people get access to flexible temp (and flow) profiles, there will be more data as to exactly what works best and how much difference it makes.    Once that is determined, then it would be appropriate to ask "can we achieve as good or almost as good taste with a simpler system".
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 254
Location: Americas
Expertise: I like coffee
Posted Wed Sep 25, 2013, 9:10am
Subject: Re: Computer controlled flow
 

Photo of scale (a load cell is under the stainless steel square) and micro-controller board.  I took the load cell and plate from a $8 scale and amplified the output with an INA128 op amp.

jonr: classic.JPG
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