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Thread: PID Temp Control for less than $50

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    PID Temp Control for less than $50

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hey Guys,

    A while back I ordered the parts needed for a PID controller on the temperature for my Breville Cafe Roma.
    This may intrest people as I know that some people are paying hundreds of dollars for these things, but with a little electronics Knowledge, I have set this up for a fraction of the price.
    Ebay PID controller: $15
    Ebay Thermocouple: $2
    Ebay Solid State Relay: $5
    Parts I aready have: Misc wire/cable, tape, wood for an enclosure, tools etc. (yeah im a bit of a hoarder ;)

    Now the PID i recieved had a 3A internal relay, I had to unsolder this and solder some wires so I could hook it up to my SSR, so some electronics knowledge is required for the parts I used.

    The last of the parts only arrived last night, so I have only done basic bench tests. I still have to make the enclosure and wire it up neatly.
    The temperature before the PID was ranging from mid 80s to about 110 degrees max, which pretty much sucks.
    From initial testing, this this is just magical I set it to 96 degrees, it heated to 80 something, switched the element off, slowly got to 96 and then it just blips the element occasionally to keep it at the temp.

    I am very impressed with this so far, and provided these cheap parts dont break on me, its a bargain!
    I will post more once I have set it up properly!

  2. #2
    Senior Member artman's Avatar
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    Re: PID Temp Control for less than $50

    Sounds like a great little DIY project for the tinkerers (suitably qualified of course).

    Simplistically, Does PID basically get its input from its own temp sensor and switch the wires that connect to the original temp sensor? Or is it way more complicated than this?

    Cheers

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    Re: PID Temp Control for less than $50

    Hi artman,
    Yeah, thats exactly how it works :)
    I will post pictures when I am done!

  4. #4
    Senior Member artman's Avatar
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    Re: PID Temp Control for less than $50

    Nice, look forward to it. Would be a great little project to add to my list of never ending projects!!

    Does the temp sensor simply sit on the outside of the boiler, or is it inserted into the boiler to measure the actual water temp? I guess it depends on how quickly the brass boiler changes temp in relation to the water inside it.

    Cheers

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    Re: PID Temp Control for less than $50

    Sensor location is tricky. My machine is actaully a thermoblock machine, Currently I have the sensor pushed against the outside of the thermoblock with some computer heatsink paste inbetween, very close to the location of the original thermostats.
    It does seem to take a long time for the heat to actaully reach the thermostat, but the PID should help with that.
    I guess a thermoblock machine is never going to be great, but Im hoping it will be a LOT better than what it was before.
    I would imagine that ideally if you had a boiler machine youd want to be measuring the water temp in the boiler, but I personally would be too afraid that I wouldnt be able to seal it well enough after drilling into it. I think most people just attatch the sensor to the outside though.

    I will be measuring the water temperature as it comes out of the machine too, as I suspect that I will need to set a higher temperature on the PID than 96 to produce 96 degree water.

  6. #6
    KJM
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    Re: PID Temp Control for less than $50

    Quote Originally Posted by 615F5A5D5F360 link=1334794026/0#0 date=1334794026
    Now the PID i recieved had a 3A internal relay, I had to unsolder this and solder some wires so I could hook it up to my SSR, so some electronics knowledge is required for the parts I used.
    Small beer, but worth noting - if the PID was set up to switch a relay, itll be configured for long on and off times. Relatively speaking anyway - so you probably wont see much shorter times than 2 seconds. Depending on the controller you should be able to mess about with the parameter block to re-config this to be SSR compatible - down to single cycle. Dont go lower though - the usual SSR suspects have zero cross detect, so youll end up with strangely dysfunctional heating if you get too crazy about it.

    Good buying, I have to say.

    /Kevin

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    Senior Member brettreaby's Avatar
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    Re: PID Temp Control for less than $50

    the type i got for about the same price included the SSR output ( N2006P ) so no need to make any internal mods. Also came configured to work the SSR output nicely on my behmor. This model actually also includes a 3A output as well as the SSR - are you sure your model is relay output only?

    Quote Originally Posted by 08363334365F0 link=1334794026/0#0 date=1334794026
    Now the PID i recieved had a 3A internal relay, I had to unsolder this and solder some wires so I could hook it up to my SSR, so some electronics knowledge is required for the parts I used.

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    Re: PID Temp Control for less than $50

    Ah ok, I didnt know that, thanks Kevin, ill have a play and see what i can work out.

    brettly, the model is REX-C100FK02-M-AN
    datasheet here: http://www.fmfranklin.com.au/products/data/rkc/c100inst.pdf

    As you can see, this brand has different models for voltage pulse output and relay output, and they use the same pins. I realised this after id already bought it, I emailed the seller to see if they had the voltage pulse model but they didnt.

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    Re: PID Temp Control for less than $50

    Just looking at that datasheet, looks like the setting you are talking about Kevin is "Proportional Cycle" lets me set from 1 to 100 seconds, so i guess ill just make sure that is set to 1.
    Thanks heaps for that, definitely something i would never of even looked at :D

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    Senior Member brettreaby's Avatar
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    Re: PID Temp Control for less than $50

    quite different in the programming to the n2006p.

    correct- propotional cycle is the setting.to play with.

    actually it looks like an RKC rip off ( see the bottom ) - they are a famous Japan brand and i doubt they sell their PIDs for $15!


    Quote Originally Posted by 516F6A6D6F060 link=1334794026/7#7 date=1334890566
    brettly, the model is REX-C100FK02-M-AN
    datasheet here: http://www.fmfranklin.com.au/products/data/rkc/c100inst.pdf

  11. #11
    KJM
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    Re: PID Temp Control for less than $50

    Quote Originally Posted by 47797C7B79100 link=1334794026/8#8 date=1334891106
    Just looking at that datasheet, looks like the setting you are talking about Kevin is "Proportional Cycle" lets me set from 1 to 100 seconds, so i guess ill just make sure that is set to 1.
    Thanks heaps for that, definitely something i would never of even looked at
    As I said - probably in the small beer category - heating things tend to have so much in built "inertia" that the difference between 1, 2 and 5 second cycling might be hard to detect. But in a Thermoblock design, you probably do want it to be as fast as possible..

    /Kevin

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    Re: PID Temp Control for less than $50

    done. works like a charm :D
    picture attached


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    Senior Member artman's Avatar
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    Re: PID Temp Control for less than $50

    Good work! [smiley=thumbsup.gif]

    Do you have any info in regard to what parts you used, the wiring details etc?

    How do they work for the steam setting? Or is it only for brew and gets bypassed for steaming?

    Cheers

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    Re: PID Temp Control for less than $50

    Quote Originally Posted by 382B2D343837590 link=1334794026/12#12 date=1335091762
    Good work!* [smiley=thumbsup.gif]

    Do you have any info in regard to what parts you used, the wiring details etc?

    How do they work for the steam setting?* Or is it only for brew and gets bypassed for steaming?

    Cheers
    Thanks!
    Parts: pretty much all from ebay. not sure if i am allowed to link them here?
    http://www.ebay.com.au/itm/SSR-25-DA-Solid-State-Relay-PID-Temperature-Controller-25A-Output-24V-380V-/280776557335?pt=AU_B_I_Electrical_Test_Equipment&h ash=item415f964317
    http://www.ebay.com.au/itm/Dual-Digital-PID-Celsius-Temperature-Control-Controller-Thermocouple-REX-C100-/230753283975?pt=AU_Gadgets&hash=item35b9f7af87
    http://www.ebay.com.au/itm/1M-3-3ft-K-Type-Thermocouple-Control-Temperature-Controller-0-400C-Sensor-Probe-/280849287636?pt=AU_Electronics_Accessories_Wires_C ables&hash=item4163ec09d4

    But as I said, I got the wrong PID and needed to unsolder the internal relay and solder wires for my solid state relay. so you have to make sure everything you buy will work with each other. most PIDs seem to use K type thermocouples.

    I have seen kits which come with PID, SSR, and Thermocouple for $42 such as this one, so you know what you are buying will all work together:
    http://www.ebay.com.au/itm/AC-100-240V-PID-Digital-temperature-controller-25A-SSR-K-Sensor-Thermostat-/220890859067?pt=AU_B_I_Electrical_Test_Equipment&h ash=item336e1f063b
    But that is like twice what i paid buying them individually.

    For the cabling, I just cut up an old power lead I had, then I used some heat proof braid tube stuff from jaycar to protect it.

    When I started this project, I was thinking, hey anyone could do this, I could make a kit and sell it. But as I was wiring it up, I released that every machine is going to be different, you have to trace back the wires and work out how to modify it.

    For my machine, I have left it so when you switch to steam, the heating element is just hard on, bypasses the PID, same as factory.

  15. #15
    Senior Member artman's Avatar
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    Re: PID Temp Control for less than $50

    Thanks for the info, it looks relatively straight forward. I must give this a go when I get a chance.

    Cheers


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    Re: PID Temp Control for less than $50

    Hi Wilki!

    i have just received the REX-C100FK02-M AN temp controller which i bought off ebay, and have now discovered it will not run my SSR... is there any chance you could put a picture up of the solder jump wire modifications you made? any help would be GREATLY appreciated!!!!

    Thanks!

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    Re: PID Temp Control for less than $50

    Guys,
    * ** ** *When i did my Silvia PID, i got the small (din 32) XMT7100 unit that has 3A relay and SSR outputs. ($20)
    But, before installing the SSR, i ran the unit simply using the internal relay to switch the heater on/off.
    I only did that because i noticed that the relay was a Panasonic actually rated for 7 amps @ 250v.* :o
    This was a extremely simple install with only 3 wires to the PID..live, neutral, and one live feed back to the heater element. !
    I ran fine that way without the SSR for several days with the cycle timer set to 1 sec ( minimum)
    I only fitted the SSR to eliminate the "clicking" of the relay as it operated !* :D ;D

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    Hey, liamjgough.
    Sorry it has taken me so long to see this. Hopefully I can still help.

    I have mine nice and boxed in my coffee machine, so I'd prefer not to dismantle it, but if you can post some pictures of your board I could draw a line in mspaint for you

    7A relay, nice blend52!

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    So, the milion dollar question; how is the coffee?

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    Bear in mind that the accuracy of a K-type thermocouple is +/- 2.5degC for the range we're interested in (though you can get higher accuracy, +/- 1.5degree units but I doubt a cheap evilBay purchase is likely to be one of those).

    Ideally you want a T-type thermocouple (and many cheaper PID controllers won't talk to these) which is +/- 1.0degC for the lowest accuracy class, +/- 0.5 for the highest.

    Oh and I wouldn't recommend running a 7A load through a PID rated for 3A regardless of what the relay rating is (especially if it's a cheap PID), the connections between the relay and the screw terminals would have been designed to handle 3A, so although it may have worked for a while, it is a potential fire hazard as whilst the tracks aren't likely to fail immediately, they will heat significantly more than they were designed to.

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    I read it he brought out the ss control wires to the ssr mounted external to the control: unlikely the ssr would fit inside the pid. In which case no problem. But it's good practice to mount the ss on a metal base if it's a metal body.

    Quote Originally Posted by jbrewster View Post
    Bear in mind that the accuracy of a K-type thermocouple is +/- 2.5degC for the range we're interested in (though you can get higher accuracy, +/- 1.5degree units but I doubt a cheap evilBay purchase is likely to be one of those).

    Ideally you want a T-type thermocouple (and many cheaper PID controllers won't talk to these) which is +/- 1.0degC for the lowest accuracy class, +/- 0.5 for the highest.

    Oh and I wouldn't recommend running a 7A load through a PID rated for 3A regardless of what the relay rating is (especially if it's a cheap PID), the connections between the relay and the screw terminals would have been designed to handle 3A, so although it may have worked for a while, it is a potential fire hazard as whilst the tracks aren't likely to fail immediately, they will heat significantly more than they were designed to.

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    Quote Originally Posted by jbrewster View Post
    Oh and I wouldn't recommend running a 7A load through a PID rated for 3A regardless of what the relay rating is .
    Fair comment,..but to be clear.....
    1) I was not running 7 A through it...the Silvia element pulls little over 4 A max
    2) I expect most elec designers build in a little safety margin ? ( maybe thats why they used a 7A relay !)
    3) the current draw is not continuous. 5 mins to initial heat from cold, then cycling for a few seconds at a time.
    4) It was a test..never intended to be permanent. ( Though i believe it is perfectly viable if you can tolerate the solenoid clicking !)

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    Quote Originally Posted by MrJack View Post
    So, the milion dollar question; how is the coffee?
    For me? Very hard to say. I have too many inconsistencies to be able to tell sadly.
    I mostly just enjoy hacking things

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    Quote Originally Posted by brettchris View Post
    I read it he brought out the ss control wires to the ssr mounted external to the control
    No, he removed the internal relay and ran the lines which were driving that out to the SSR (I've done this myself on several PIDs) but initially he was running the element directly off the internal relay.

    Quote Originally Posted by blend52 View Post
    1) I was not running 7 A through it...the Silvia element pulls little over 4 A max
    Whilst this is true, people with less experience in these matters might think "awesome I can run 7A through this" because they are not aware of the other considerations here. Also, good engineering practise dictates an 80% derating (5.6A in this case), i.e. you don't run things close to the rating on the spec sheet.

    Quote Originally Posted by blend52 View Post
    2) I expect most elec designers build in a little safety margin ? ( maybe thats why they used a 7A relay !)
    On dirt-cheap chinese mass-production? Highly doubtful. I'd be surprised if the tracks are even appropriate for the rating on the box, copper is expensive and given the space constraints the way you'd get extra current handling is to use 2oz copper instead of 1oz, which means the whole board becomes more expensive.

    A relevant anecdote, Jeri Ellsworth replicated the Commodore 64 in a joystick for some toy company or other, when the designs got shipped to the factory in China they couldn't get the prototypes to work, when she went over there to check it out she found that they'd removed a large number of essential components like bypass capacitors in order to reduce costs, high-speed digital systems don't work without proper bypassing.

    The 7A relay would be because it fit and they could buy a few hundred thousand of them at a few cents a pop, the current rating has little bearing on the cost of such relay when you're buying in those sorts of quantities.

    Quote Originally Posted by blend52 View Post
    3) the current draw is not continuous. 5 mins to initial heat from cold, then cycling for a few seconds at a time.
    Valid point, the main concern would be the initial warm up period.

    Quote Originally Posted by blend52 View Post
    4) It was a test..never intended to be permanent. ( Though i believe it is perfectly viable if you can tolerate the solenoid clicking !)
    Barring the bit where the electromechanical relay dies after about 10,000 cycles (100,000 for better relays)

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    Quote Originally Posted by jbrewster View Post
    No, he removed the internal relay and ran the lines which were driving that out to the SSR (I've done this myself on several PIDs) but initially he was running the element directly off the internal relay.



    Whilst this is true, people with less experience in these matters might think "awesome I can run 7A through this" because they are not aware of the other considerations here. Also, good engineering practise dictates an 80% derating (5.6A in this case), i.e. you don't run things close to the rating on the spec sheet.



    On dirt-cheap chinese mass-production? Highly doubtful. I'd be surprised if the tracks are even appropriate for the rating on the box, copper is expensive and given the space constraints the way you'd get extra current handling is to use 2oz copper instead of 1oz, which means the whole board becomes more expensive.

    A relevant anecdote, Jeri Ellsworth replicated the Commodore 64 in a joystick for some toy company or other, when the designs got shipped to the factory in China they couldn't get the prototypes to work, when she went over there to check it out she found that they'd removed a large number of essential components like bypass capacitors in order to reduce costs, high-speed digital systems don't work without proper bypassing.

    The 7A relay would be because it fit and they could buy a few hundred thousand of them at a few cents a pop, the current rating has little bearing on the cost of such relay when you're buying in those sorts of quantities.



    Valid point, the main concern would be the initial warm up period.



    Barring the bit where the electromechanical relay dies after about 10,000 cycles (100,000 for better relays)
    If the tracks did burn out and you still wanted to use the relay, you could always open her up and solder wires directly to the relay

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    Quote Originally Posted by Wilki View Post
    If the tracks did burn out and you still wanted to use the relay, you could always open her up and solder wires directly to the relay
    Considering 25A SSRs (not that I'd trust them for more than ~10A) go for ~$7 on evilbay I wouldn't bother, bringing the drive out (or better yet getting a PID controller with SSR outputs to begin with) is a better option, to say nothing of the potential fire hazard if the tracks should burn out...

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    Quote Originally Posted by jbrewster View Post
    No, he removed the internal relay and ran the lines which were driving that out to the SSR (I've done this myself on several PIDs) but initially he was running the element directly off the internal relay.
    I think there is some confusion between posts here ..
    To clarify further,..the PID, i used was the small (din 32) XMT7100 unit that has 3A ( 7A actual) relay, AND SSR outputs. (for $20)
    So i didnt need remove the relay, run extra wires, or mess with anything internally on the PID.

    FYI : there are simpler, cheaper electronic temp controllers available ( ebay..$10) with 30A internal relays .
    They are not ideal, but they will hold a temp much closer than the stock bi-metal T'stats fitted as standard, and give a digital temp display.
    The display itself is a huge help in getting consistent shot quality, and reducing a temp variation from 30 C,... to 5 C , is a bonus !

  28. #28
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by jbrewster View Post
    Barring the bit where the electromechanical relay dies after about 10,000 cycles (100,000 for better relays)
    700,000 cycles or even more on the good non-Chinese ones: http://coffeesnobs.com.au/showthread...l=1#post279955


    Java "You want to relay what?!?" phile
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    Quote Originally Posted by Javaphile View Post
    700,000 cycles or even more on the good non-Chinese ones: http://coffeesnobs.com.au/showthread...l=1#post279955
    Heh, at what percentage of maximum ratings? I generally divide MTBF/other reliability figures by 5-10 to get something more reflective of reality ;P

    If it's worth engineering it's worth over-engineering ;D

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    Quote Originally Posted by blend52 View Post
    To clarify further,..the PID, i used was the small (din 32) XMT7100 unit that has 3A ( 7A actual) relay, AND SSR outputs. (for $20)
    So i didnt need remove the relay, run extra wires, or mess with anything internally on the PID.!
    Ahh, must've been somebody else who commented about bypassing the relay.

    the XMT7100 isn't a bad unit actually, I use two of them (one for boiler control the other is a group temperature display), I bypassed the alarm relay in the boiler control unit so I could direcly drive my steam control SSR.

  31. #31
    Super Moderator Javaphile's Avatar
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    Quote Originally Posted by jbrewster View Post
    Heh, at what percentage of maximum ratings? I generally divide MTBF/other reliability figures by 5-10 to get something more reflective of reality ;P

    If it's worth engineering it's worth over-engineering ;D
    While I would agree with this for cheap Chinese parts these relays were made in Switzerland.

    The original relay was rated for 1,000,000 cycles. The machine was in a commercial setting for ~14 years where it was left on 24/7 year-round and then ran here 24/7 for 8 months out of the year for 7 years. Using the avg cycle time as measured here that means the relay had almost 2,000,000 cycles on it when it died. I'd say it's fair to say the relay was over-built and that their stated duty life was pretty fair reflection of what to expect in reality.


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    Quote Originally Posted by Javaphile View Post
    While I would agree with this for cheap Chinese parts these relays were made in Switzerland.
    Ahh, yeah, fair enough, the Swiss know how to engineer stuff (refer to earler comment about over-engineering)

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    Modification of REX-C100 PID

    Hi Wilki,

    I had just received my REX-C100 with relay output. I wish to modify the pid to SSR output as you did. I have the required electronics knowledge for the jib, but not sure the proper way of opening up the PID casing (without demaging the plastic casing).

    Thus I would appreciate very much if you show me the way to do it.

    Regards.
    Tanke

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    Quote Originally Posted by Tanke View Post
    Hi Wilki,

    I had just received my REX-C100 with relay output. I wish to modify the pid to SSR output as you did. I have the required electronics knowledge for the jib, but not sure the proper way of opening up the PID casing (without demaging the plastic casing).

    Thus I would appreciate very much if you show me the way to do it.

    Regards.
    Tanke
    I managed to open up the casing with ease. No "cracking" is necessary. The modification is straight forward.

    Thanks.

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    Hi Guys, I dug up this thread, as I'm looking at sourcing a C100 (or maybe C700) from dx.com to mod my Silvia. For those of you who've installed a C100 (or similar), did you manage to wire it up to automatically change the temp depending on the active function? or do you manually dial in the temp on the controller, and wait until the thermocouple reads the right temp, then use whatever machine function you require (eg hot water/steam/brew)?

  36. #36
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    Behmor Brazen - $249 - Free Freight
    Sorry to exhume such an old thread but fascinating read and such a shame there wasn't able to be a few more pix or general instructions for folks to follow as I'd imagine a LOT of people would definitely be interested in doing something like this given the low cost vs high reward ratio of the exercise.

    Great post by the OP and love to see more from him or anyone who's done anything similar.



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