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replacing Giotto controller with a DIY controller

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  • iaindb
    replied
    wow the last quarter of last year was tough... I still haven't finished this project. I have built the software and assembled the controller, but that's it.

    I'm thinking of a Panasonic AQA411VL 25A SSR, as that's what coffee parts sells for similar machines. Yet to get that.

    In the meantime I wired the relay via the pressurestat switch. It's rated for 240V but I know they burn out after some time (hopefully a couple of years of light use).
    Attached Files

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  • Barry O'Speedwagon
    replied
    Originally posted by iaindb View Post
    Le parts have arrived. They're quite tiny!

    [ATTACH=CONFIG]23055[/ATTACH]
    Les parts

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  • iaindb
    replied
    Le parts have arrived. They're quite tiny!

    Click image for larger version

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  • iaindb
    replied
    Originally posted by Dimal View Post
    The P/stat contacts will be fine and designed to handle the miniscule load placed on them (a relay coil).
    The relay main contacts are well able to handle the load required of them.
    We're talking passed each other... Perhaps I'm not explaining myself properly. But nevermind, my parts have arrived so I'll wire it as it is currently.

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  • Dimal
    replied
    Originally posted by iaindb View Post
    Yes, when comparing identical load and voltage, but I'm referring to the GPP wiring which is either a) low voltage (5V/12V?) DC negligible load on the pressurestat; or b) 240V AC carrying 1500W!
    The P/stat contacts will be fine and designed to handle the miniscule load placed on them (a relay coil).
    The relay main contacts are well able to handle the load required of them.

    Mal.

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  • iaindb
    replied
    Originally posted by Dimal View Post
    Given identical load and voltage, DC Contacts need to be a bit beefier
    Yes, when comparing identical load and voltage, but I'm referring to the GPP wiring which is either a) low voltage (5V/12V?) DC negligible load on the pressurestat; or b) 240V AC carrying 1500W!

    Buuuuut I'm trying to get some clarity on the Giotto wiring "versions", as I've seen wiring diagrams saying the in-line pressurestat is the latest, but the one posted above says the pressurestat wired separately to the control box is the latest...

    thanks!

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  • Dimal
    replied
    Originally posted by iaindb View Post
    So are you saying the DC pressurestat is a problem?
    Given identical load and voltage, DC Contacts need to be a bit beefier and have a means of quenching (usually magnetic) the arc resulting when the contacts are opened while loaded. This scenario doesn't apply when being used for an AC load.

    That's why it is always important to properly specify relays/contactors for the type of load to which they will be subjected.

    Mal.

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  • iaindb
    replied
    I’ve ordered the screen to play with, but it probably won’t go on the final version as I’m mounting the whole lot inside the machine...

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  • Jackster
    replied
    I been browsing the wemos mini, will you run the screen and SD card as well?

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  • iaindb
    replied
    Thanks Mal, I happily defer to your expertise as I’ve seen inside a grand total of 1 of these machines!

    So are you saying the DC pressurestat is a problem?

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  • Dimal
    replied
    Originally posted by iaindb View Post
    You can see the two different wiring options in this PDF: https://www.home-barista.com/downloa...E-13.03.09.pdf
    Or, maybe this one...
    https://coffeesnobs.com.au/attachmen...a-part2of2.pdf

    Mal.

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  • Dimal
    replied
    Originally posted by iaindb View Post
    From what I can gather the AC eventually burns out the pressurestat switch.
    That's more of a DC issue Iain.
    Not so much with AC since at halfway through every cycle, the voltage is Zero....

    Mal.

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  • iaindb
    replied
    Originally posted by Jackster View Post
    I have a similar issue, but my pressurestat runs ac to it. My SSR are DC triggered, so waiting for some ac-ac SSR to arrive.

    But watching this to see where you end up...
    You could probably rewire it, as I think this ac pressurestat was redesigned to use the same pressurestat as a dc input. From what I can gather the AC eventually burns out the pressurestat switch.

    You can see the two different wiring options in this PDF: https://www.home-barista.com/downloa...E-13.03.09.pdf

    Leave a comment:


  • Jackster
    replied
    I have a similar issue, but my pressurestat runs ac to it. My SSR are DC triggered, so waiting for some ac-ac SSR to arrive.

    But watching this to see where you end up...

    Leave a comment:


  • iaindb
    replied
    For those following, I've ordered a Wemos D1 mini, as it has plenty of DIO, one analog input I can use later for the PID, and includes WiFi on-chip. It has relay shields, but I'll need a separate SSR for the element - probably a Fotek 25A or something like that - it will need to trigger off 3.3V. Just waiting on APost to deliver the parts!

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