GoAway Senior Member Joined: 19 Mar 2004 Posts: 65 Location: dregs Expertise: I love coffee
Posted Mon Mar 22, 2004, 5:36pm Subject: all this PID silliness for $10
... or is that PID stupidity? Are you PID people for real? Don't knee-jerk, keep reading please.
I cannot tell how many think it truly makes a big difference and how many are just gear junkies willing to try anything to improve their espresso. Do you think it really makes that much difference, more to the point: do you think that your path to espresso extraction perfection is that fragile and elusive? The manufacturers base their units on the fact that it will make great espresso as-is; in fact they pretty much base their futures on it. Ignoring all that, you must know you can get other thermostats. You can get bimetal low-differential thermostats in any temperature you might want for a couple bucks. So if your Gaggia turning on at 99 and off at 107 is too wide, you could make it 103 / 105. Or whatever. A lot cheaper than those PID setups. I think some people just like the lights. :^)
Seriously the reason I ask: Any of these circuits can be implemented in a $1.99 microcontroller. You could easily add a thermocouple and an isothermal barrier with a baseline ambient comparator, a snubberless triac to switch the heater coils, and some form of user interface (maybe two buttons for up/down 0.1C?) This could be implemented including some safety code to prevent boiler runaway and a resettable fuse, display and all, for around $10usd. And that's retail Q:1 pricing. You could have boards etched and stuffed at a commercial level for pennies. It would be small enough to fit inside any unit and you can heatsink the triac to the chassis, afterall it's made to hold a freakin' boiler! The readout & buttons could be an external box that just took the internal thermo cutoff(s) out of the circuit when attached and powered - so that the espresso machine would function normally (it's factory supplied behavior) if the uC dies, locks up, or is detached. All for cheaper than a 10A SSR alone.
Hell, you could store temperature curves, profiles. Wouldn't need much EEPROM space to store a few variables. You could have it automatically compensate against ambient temp, altitude adjustments for the lower boiling point, whatever you can imagine might help you along to espresso perfection. You seem an imaginitive bunch! :^) Besides there's enough geeks here. I'm sure there are some hardware geeks, some pcb fab geeks, some uC programmer geeks. There would be some design considerations not the least of which would be compensating the whole circuit for the thermal environment it'd be operating in.
It could be a fun open source / open hardware group project.
Coming full circle: Are you PID people for real?
Now, now; perfectly symmetrical violence never solved anything!
Posted Mon Mar 22, 2004, 7:09pm Subject: Re: all this PID silliness for $10
I don't think anyone has bought a PID thinking that it is the only path to a great shot. I haven't seen anyone make those claims either.
When I wanted any sort of consistancy on my Silvia I had to temp/time surf. That is really the only solution without spending any money at all. The problem with that is that I had jugs full of water that I had dumped out of the machine in order to cycle the boiler and start counting. I also had to time everything just right so that I could grind, tamp, and lock before the timer went off. If I missed that for any reason I would have to do it all over again or get a shot at a different temp.
Now...in comes the PID. I walk up to the machine and it's ready to go. I can take my time and not have to run off any water. The machine is just ready to go at the temp that I choose. I can control the temp within a degree and easily change to whatever temp I want within seconds...which is not really possible with any surfing method.
Is it worth it? To me, sure. To you it may not be...
As far as the rest of your post...those seem like good ideas but I highly doubt everyone has the equipment/skill to produce something like that. You should try them and come up with a working example. Maybe people would start doing it that way instead of installing a PID.
But seriously, let's look at the details.
The ranges you give (103/105) are not nearly as accurate as a PID (but accurate enough I guess)
I have no idea what a isothermal barrier with a baseline ambient comparator and a snubberless triac are. No idea at all. I knew what a PID was before I had even owned an espresso machine.
Then I would need to write some sort of safety code and get a resettable fuse with a display.
Then I need someone to etch boards for me which I know nothing about or what to even ask them for even if I could find someone to make one for me....for pennies.
Then I would have to take a course on electronics to figure out how to set all of this up.
I forgot to buy an EEPROM burner (how much are those anyways?) and read a book to learn how to program it. Then learn how to write a program to compensate against ambient temp, alititude adjustments, etc.
Toss in a soldering iron (mine is junk) and any other equipment needed to put it together too. Then add in the time it takes to do all of this (time is money you know). I think I just saved a fortune buying that silly PID!
I know you are wondering if the PID people are real....but seriously...are you for real? I mean...we could build an espresso machine from scratch too and probably save a dollar or two....maybe.
We should call MacGyver. He could build a PID out of a flashlight, a toothpick, and some chewing gum. Where is that guy when you need him?
*tongue planted firmly in cheek*
Ok, I lied...Basically I installed the PID to impress women.....oh....and the pretty lights.
GoAway Senior Member Joined: 19 Mar 2004 Posts: 65 Location: dregs Expertise: I love coffee
Posted Tue Mar 23, 2004, 6:58am Subject: Re: all this PID silliness for $10
"but I highly doubt everyone has the equipment/skill to produce something like that"
Yea? I highly doubt most people understand how electricity works. At the most basic level. Or an internal combustion engine. Doesn't stop them from using them. (How many instant vegetarians would we have if everyone had to slaughter what they ate, for that matter?) You don't have to understand nor have the skills to design or assemble it. There are electronics geeks that do. That just happen to drink espresso. And besides there's other hobbyist fields that already have these DIY types of temperature controllers: Ceramics kilns, glass blowers, smelting furnaces, etc. We could adapt an existing project although truthfully I don't see any serious design hurdles. I threw that out off the top of my head when I was researching what this PID stuff was, how many were serious about it. I'd think you were all a bunch of whacko nutjobs except that Schomer is where you got the basic idea from. What I outlined is probably not the best way to do it. I was fishing for others interested enough to discuss it.
Check out some of the other community-driven DIY electronics projects. I was thinking something along the lines of the MegaSquirt EFI computer. The PCB and a component list made available, then the community at large could help put photos and documentation of installs, help troubleshoot, make software modifications, faster response temperature probe solutions, etc etc. Where a core group actually does the work but everyone can benefit and provide input. A few devotees sell assembled units for those that don't know the business end of a soldering iron. (supporting the notion that for every capitalist thinking "time is money" there's a geek thinking "knowledge is power" - not mentioning capitalist geeks thinking "knowledge is money".. :^)
Here's the one basic premise I haven't picked up from the archives: Is it just temperature or is it the total control of all variables? For example would a PID believer think a lever/piston machine is useless as the human-supplied extraction pressure is too variable? Believer. Sounds like a religon. Wait, a subsect of the overall espresso religion... we're all zealots anyway.
PS: (Atomic_Dave) Point #1 in your list. That is for a replacement thermostat costing just a couple dollars, not the controller I described. The controller be balls-on accurate as any PID you can buy down to the sensitivity limits of whatever probe is used. No, that is a thermostat just like the one your unit came with only with a lower differential. (technospeak for a narrower range between the on/off trip points.) Someone interested in raising and/or stabilizing the temperature after surfing a bit might think this is more feasable, it's both simple and cheap. But I do not see it discussed.
Now, now; perfectly symmetrical violence never solved anything!
gscace Senior Member Joined: 19 Dec 2001 Posts: 237 Location: Laytonsville, MD USA Expertise: I live coffee
Espresso: La Marzocco Linea 2AV, Astra... Grinder: 3 Mazzers Robur, Kony,... Vac Pot: Cona D, Hario Nouveau Drip: Technivorm Roaster: Has Garanti 1kg. electric
Posted Tue Mar 23, 2004, 7:38am Subject: Re: all this PID silliness for $10
Hey there:
I'm not an electrical engineer. I'm a coffeegeek and a mechanical engineer with some temperature expertise and a smattering of controls practice. My comments:
I don't take it on faith that manufacturers make machines designed to make good espresso. If you drink espresso made at both the upper and lower extremes of temperature produced by most home machines, then you would agree that something could be done to improve things. And some machines suck to begin with. Just how does your assertion that manufacturers produce good enough machines support the existence of the world crop of steam toys? I think that manufacturers will build what they can get away with, and if folks like us want better from them we need to demand it en mass, or do it ourselves.
WRT to on-off control and installing smaller range deadband controllers - the heating element's size in relation to the boiler volume means that there will be a large temperature overshoot, despite the window size of an on / off control system. The overshoot is several degrees C for the Silvia - nontrivial. So just changing thermostats doesn't cut it.
I originally installed proportional control using a commercial PID controller because it's relatively inexpensive to do so, has a lot of bang for the buck, and is a very good solution that doesn't require a lot of thought or effort. My time is worth something. I'm not particularly interested in building electronic devices, and a system comprised of several commercially available components that doesn't require an advanced degree or a great deal of expertise to assemble is easily duplicated by others. I know plenty of controls people who could complete the exercise by building a control circuit into an electronics package to run their machines, but that's way harder to do on a one-off basis and it doesn't help others, unless it's made available commercially. Guess no one's stepped up to that, but maybe you're gonna?
Is it worth it? The data is on usenet. Search google groups for Temperature Study of my Sylvia (loooong). Note that Silvia is misspelled. Also search for articles on proportional control of sylvia and PI control of sylvia. I used to misspell Silvia a lot, unfortunately. I did the measurements in 1991, and did the first proportional control work then as well, along with Andy Scheckter. The data's there and it is compelling. I'll put my Silvia up against any commercial machine for temperature stability, shot to shot performance, and taste of the coffee.
-Greg Scace
By the way - I don't know anyone who has removed their PID from their machine after trying it out.
gscace Senior Member Joined: 19 Dec 2001 Posts: 237 Location: Laytonsville, MD USA Expertise: I live coffee
Espresso: La Marzocco Linea 2AV, Astra... Grinder: 3 Mazzers Robur, Kony,... Vac Pot: Cona D, Hario Nouveau Drip: Technivorm Roaster: Has Garanti 1kg. electric
Posted Tue Mar 23, 2004, 2:09pm Subject: Re: all this PID silliness for $10
If you make lots of milk drinks, then the simultaneous brewing / steaming capability of the hx machine is useful. If you're pulling straight shots at duty cycles up to 1shot every 1.5 mins, then PID control on a Silvia is cheaper than any HX machine by far, since you already own the machine. You could sell it and then upgrade, but it'll still cost a couple hundred more for the HX and HX machines won't give you the same stability unless you get a really big boiler and a HX machine that plays tricks with brew temps external to the HX. for example, I just saw an ECM 2-group that mixed the hot water from the HX with cold feedwater to control temperature to the group. It was an expensive machine too - several thousand bux.
Posted Tue Mar 23, 2004, 3:14pm Subject: Re: all this PID silliness for $10
I haven't laughed out loud whilst reading these threads for a long time. this particular thread is hilarious.
I like these threads because they get everyone talking and having a bit of a go at different ideas. having said that here is some food for thought;
i saw somewhere that there is an italian standard for espresso. i don't recall seeing anything about pid's or eprom burners in that standard.
for that matter i don't recall the standard detailing crema an inch thick which is what alot of people on this forum aspire to. why? i don't know. i love the way that my silvia makes coffee. the fact that it is not ultra consistent doesn't worry me because i don't have a thermocouple (whatever that is) stuck to my tongue to measure the exact temperature of the espresso.
Of course GoAway you are perfectly free to build what you are talking about and share your findings with the rest of us. i would be fascinated (sic) to find out how it works.
Posted Wed Mar 24, 2004, 7:04pm Subject: Re: all this PID silliness for $10
gscace Said:
Is it worth it? The data is on usenet. Search google groups for Temperature Study of my Sylvia (loooong). Note that Silvia is misspelled. Also search for articles on proportional control of sylvia and PI control of sylvia....I did the measurements in 1991
Holy cow! 1991!!!!
-Andy S.
-Andy S picture page: http://flickr.com/photos/andy_s/sets/
Symbols: = New Posts since your last visit = No New Posts since last visit = Newest post
Forum Rules: No profanity, illegal acts or personal attacks will be tolerated in these discussion boards. No commercial posting of any nature will be tolerated; only private sales by private individuals, in the "Buy and Sell" forum. No cross posting allowed - do not post your topic to more than one forum, nor repost a topic to the same forum. Who Can Read The Forum? Anyone can read posts in these discussion boards. Who Can Post New Topics? Any registered CoffeeGeek member can post new topics. Who Can Post Replies? Any registered CoffeeGeek member can post replies. Can Photos be posted? Anyone can post photos in their new topics or replies. Who can change or delete posts? Any CoffeeGeek member can edit their own posts. Only moderators can delete posts. Probationary Period: If you are a new signup for CoffeeGeek, you cannot promote, endorse, criticise or otherwise post an unsolicited endorsement for any company, product or service in your first five postings.
= No New Posts since last visit 