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Computer controlled temp and flow profiling
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Discussions > Espresso > Espresso Mods > Computer...  
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 304
Location: Americas
Expertise: I love coffee
Posted Tue Nov 26, 2013, 1:11pm
Subject: Re: shot termination
 

I'm sure all methods of measuring TDS have inaccuracies.  Drying in a vacuum might help.

andys Said:

%TDS keeps dropping, yes, but depending on how you pull your shots, it generally doesn't drop so low that it's insignificant.

Posted November 25, 2013 link

Of course not.  The point is that it crosses say 12% with a nice downward slope to it.  So it could be used as a repeatable shot termination point.  Is that better or worse than terminating based on reaching a preset shot weight?  I have no idea; my guess is that it wouldn't make much difference.

A more radical approach would be to estimate extraction yield on the fly and if it isn't matching some preset curve (ie, it looks like it will end up too high or low), do something (change pressure/flow rate?) to attempt to fix it.  This works well with controlling flow to expected levels.
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andys
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andys
Joined: 10 May 2003
Posts: 861
Location: NY
Expertise: Just starting

Espresso: Speedster, Londinium 1
Grinder: EK-43,Robur, HG One, M3
Vac Pot: Yama
Drip: various
Roaster: PIDed Popper
Posted Tue Nov 26, 2013, 3:38pm
Subject: Re: shot termination
 

jonr Said:

A more radical approach would be to attempt to estimate extraction yield on the fly and if it isn't matching some preset curve (ie, it looks like it will end up too high or low), do something (change pressure/flow rate?) to attempt to fix it.

Posted November 26, 2013 link

If it isn't matching your preset curve, do something, like have the machine automatically dump the shot in the sink so you can quickly start over.  :)

 
-AndyS
picture page:  http://flickr.com/photos/andy_s/sets/
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jkruer01
Senior Member


Joined: 16 Nov 2013
Posts: 7
Location: KY
Expertise: I like coffee

Posted Fri Nov 29, 2013, 7:23am
Subject: Re: Computer controlled temp and flow profiling
 

Jon,

First of all, great job on what you have been able to do.  I am very impressed.

I would like to implement your mods on my own Gaggia Classic.  I am a computer programmer by trade, but have never worked with Embedded chips before.  Also, I don't have much experience with wiring and electricity but am willing to learn.  

Would you be willing to help me get setup with everything I would need?  

Any help would be greatly appreciated.

Thanks!
Jeremy
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jonr
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Joined: 25 Jun 2013
Posts: 304
Location: Americas
Expertise: I love coffee
Posted Fri Nov 29, 2013, 11:08am
Subject: Re: Computer controlled temp and flow profiling
 

jkruer01 Said:

Would you be willing to help me get setup with everything I would need?  

Posted November 29, 2013 link

Yes, definitely.  We need more people using these advanced espresso machines.    The software can be as simple as loading in what I have and as you would guess from the limited number of parts, the wiring isn't very complex.
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jkruer01
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Joined: 16 Nov 2013
Posts: 7
Location: KY
Expertise: I like coffee

Posted Fri Nov 29, 2013, 11:27am
Subject: Re: Computer controlled temp and flow profiling
 

Great! Thank You.

So is this parts list still up to date and accurate?

jonr Said:

FreeScale FRDM-KL25Z for the computer.  It's only $12.95
Solid state relay (SSR),  $8
PT1000 RTD temperature sensor (low mass, it responds quickly),  $4
2K ohm precision resistor, $2
thermally conductive epoxy (to attach the sensor to the boiler)

Optional:
some firestop foam (to keep ambient air from influencing the sensor)
IGBT for high speed PWM/voltage pump control, ISL9V3040P3, $2
2 kickback diodes, $1
DS1307 real-time clock board for auto turn on, $2
Another PT1000 for logging thermofilter temp, $4
Load cell (scale) for real-time measurement of flow, $10

Posted November 29, 2013 link

Anything else that I am going to need? What website would you recommend me ordering these parts from?

Did you ever make a housing unit for everything or is it all still just hanging out?  Any pictures of your current setup?

Thanks!
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jonr
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Joined: 25 Jun 2013
Posts: 304
Location: Americas
Expertise: I love coffee
Posted Fri Nov 29, 2013, 11:58am
Subject: Re: Computer controlled temp and flow profiling
 

Still good and the Sep 25 picture is the best I have.  Let's talk offline.
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jonr
Senior Member


Joined: 25 Jun 2013
Posts: 304
Location: Americas
Expertise: I love coffee
Posted Fri Mar 28, 2014, 3:36pm
Subject: Re: Computer controlled flow
 

This is worth reading regarding humped profiles and accurate temperature control.
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kmills
Senior Member


Joined: 29 Mar 2014
Posts: 2
Location: NJ
Expertise: I love coffee

Posted Sat Mar 29, 2014, 6:55am
Subject: Re: Computer controlled flow
 

Hi Jon, I'd like to know some more specifics about the pump control if you have time. I'd like to know how you implement the 2 kickback diodes (to protect IGBT from inductive kickback from pump, right?). I would also like to know how you are driving the IGBT, the BS2 I plan to use can drive a pin high or low at ~1mSec intervals and would need to use a 555 timer if I have to drive it any faster. It seems the goal is to drop out tiny portions of a sine wave totaling ~17mSec to approximate a smooth voltage reduction.
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jonr
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Joined: 25 Jun 2013
Posts: 304
Location: Americas
Expertise: I love coffee
Posted Sat Mar 29, 2014, 9:04am
Subject: Re: Circuit diagram
 

Yes. The micro drives the gate of the IGBT directly through a 1K resistor.  The micro has hardware PWM and I run it at 2500 Hz (1KHz might work too).    The IGBT only switches DC, but that is OK since a solenoid pump only actually uses DC.  It's configured as a low-side switch.   One diode runs parallel to the pump and one is in series (to rectify, although I'm sure there is already one in the pump).   A downside to the IGBT as compared to a SSR is that it is not isolated.  A 1 amp isolation transformer should fix that (or be very careful that you always have power plug hot/neutral correct).  If you draw a circuit, I can check it.
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kmills
Senior Member


Joined: 29 Mar 2014
Posts: 2
Location: NJ
Expertise: I love coffee

Posted Sat Mar 29, 2014, 12:14pm
Subject: Re: Computer controlled flow
 

Ok thanks, Circuit diagram attached. So I am gathering that if the pump actually runs on DC only and has a diode, its running on a half-wave rectification so the IGBT only needs to see a half wave so the one diode IS sufficient. I would like to see how you have it set up with two diodes set up, though.

kmills: IGBT.jpg
(Click for larger image)
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