DIY temp controller build

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I, too, reinvented the wheel. This is my 3rd Arduino project and I see no end in sight. I am a gadget freak and they're even more fun when you roll your own.

ArduinoFridge3.jpg

http://picasaweb.google.com/lh/photo/ErWIeMiPY08-rDCzplw7V5mqNgd6qJ4RhM9wu73rcO8?feat=directlink
 
Thanks for the info android mine work great. :mug:
I used an old cellphone charger and an $5 SSR from ebay

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Its good you can do all of that stuff but those costs add up and that makes less time for the pretty stuff. For 70 bucks, why not buy the Johnson electronic (not mechanical) control with adjustable time-delay and differential and all you have to do is plug it in (and drop the probe inside). We are selling more and more of these. It takes 3 minutes to read the instructions and about 1 minute to program it.


You have kind of a valid point..to an extent. If something broke in the Johnson controller you would have to spend another $70 on a new controller. If something broke in this case you could do it much cheaper on a component-by-component basis. Plus people just love DIY and learning :) It may not be the best solution but its pretty darn cool.
 
is it possible to make this into a 2 stage temp controlleR?

East enders

well, it will function as both, but of course you have to set the function to 'heat' or 'cool' on the thermostat. and i could swear i remember reading somewhere that if you use two SSRs or something, you can get it to function that way... but it's a vague memory.

what will you be using it for? if it's a fermentation chamber, you should be able to use one of the other without too many problems. i have a dual stage temp controller that i've used for fermenting and for kegerator temp control, and i've never had to have it set up as a simultaneous cold/heat unit. my basement is typically around 60 degrees, so i either turn it to heat to ferment warmer, or cool to ferment lagers. and if you will be using this for cold temps, make sure you get a thermostat that goes down that far. I cannot use mine for a kegerator, it only goes down to like 45 or so.
 
after re-reading the whole thread, i think it's on page 2 or 3 where someone mentions how they used two SSRs to do the simultaneous heat/cool. automotive relays to be exact.
 
is it possible to make this into a 2 stage temp controlleR?

East enders

If you are talking about the Johnson unit, no-it is a single stage unit. They make a 2 stage electro mechanical unit and an electronic version but of course they are more money, like 140 to 200 or so.
 
Sorry for the bump, but I am working out my temperature controller right now, and it is quite similar to your build. You say that the SSR does not require a heat sink for this application. Just wondering if you've noticed how hot it actually gets? I am doing a dual stage controller, so I will have two SSRs in the enclosure, obviously not both running at the same time.

Trying to figure out if I might want to wire a fan into the enclosure itself, or possibly just vent it. Just paranoid about anything that can run in an unattended state. :D
 
Sorry for the bump, but I am working out my temperature controller right now, and it is quite similar to your build. You say that the SSR does not require a heat sink for this application. Just wondering if you've noticed how hot it actually gets? I am doing a dual stage controller, so I will have two SSRs in the enclosure, obviously not both running at the same time.

Trying to figure out if I might want to wire a fan into the enclosure itself, or possibly just vent it. Just paranoid about anything that can run in an unattended state. :D
hmmm, not sure what you are monitoring. Mine was a beer meister using a freezer. I can tell you that in my case, it was nuts on. I used a 4 degree range of 33 to 37, set point 35. (I like it cold) -and it never drifted outside of those parameters and tended to display set point temp most of the time-otherwise somewhere between 34 and 36. Make sure your probe connections are tight on the control. (apparently mine wasn't tight enough when I received/installed it-froze my beer. One other froze episode-make sure no one forgets to re-insert probes if you are leaving them hanging on the wall without anchoring. In short, no problem other than human error. (I didn't vent or fan the box.)
 
hmmm, not sure what you are monitoring.

Specifically looking as to the temperature swings on the SSR itself. Due to it switching AC, my concern is actually that the junction box, itself, might become too hot as opposed to the contents of the fermentation chamber it will eventually be installed on.

The comments about leaving it unattended are related to not wanting to head out for the weekend and come back to a melted down junction box from excess heat build-up, or worse. :D
 

Nice project. Just one tip for the future when wiring stuff like outlets. Wrap the wire in the direction you are tightening the screw. This will pull the wire into and around the screw and apposed to try and twist itself out when you are tightening the screw down over the wire. AKA, bring the wire looped from the left to the right instead of right to left like in the picture above. :mug:
 
Nice project. Just one tip for the future when wiring stuff like outlets. Wrap the wire in the direction you are tightening the screw. This will pull the wire into and around the screw and apposed to try and twist itself out when you are tightening the screw down over the wire. AKA, bring the wire looped from the left to the right instead of right to left like in the picture above. :mug:

yes! thanks for mentioning this... i actually ended up putting a terminal adapter thingy on the end of this wire because i didn't like the way that looked.. but good advice on wiring it in the tightening direction.
 
Specifically looking as to the temperature swings on the SSR itself. Due to it switching AC, my concern is actually that the junction box, itself, might become too hot as opposed to the contents of the fermentation chamber it will eventually be installed on.

The comments about leaving it unattended are related to not wanting to head out for the weekend and come back to a melted down junction box from excess heat build-up, or worse. :D

i really wouldn't be concerned about it, but it's totally up to you if you want to put a vent/fan of some sort in there. mine has run fairly continuously for the last 6 months off and on and even when it's been controlling a heater for a week straight, when I go to move it, it only feels like ambient temperature. the plate that covers the junction box has a little opening on one side, so that sort of acts as a vent I guess... but it's never felt hot or even warm to the touch and like I said, I use this fairly often.
 
i really wouldn't be concerned about it, but it's totally up to you if you want to put a vent/fan of some sort in there. mine has run fairly continuously for the last 6 months off and on and even when it's been controlling a heater for a week straight, when I go to move it, it only feels like ambient temperature. the plate that covers the junction box has a little opening on one side, so that sort of acts as a vent I guess... but it's never felt hot or even warm to the touch and like I said, I use this fairly often.

Thanks for taking the time to reply. I though that was what you were implying. I don't imagine that we are drawing enough current with this application to be a concern. I like the idea of a small air gap on the edge of the enclouse, as venting is just going to invite dust and I would need to create pressure from the inside (i.e. a fan) to help keep the dust out.

I guess the best way to find out will be when I put it together, after the SSRs make their way from the Orient. :D
 
plus, it's not like they'll both be running at the same time. if anything, with the dual controlling, it should spread the running between then SSRs and i bet it'll all be good.
 
Can someone please send me the complete instructions?

Augie

?? the instructions are outlined in this thread and you will have to follow a link or two on the first page for the original instructions and wiring diagram. updated photos are on page 3 with the finished product IIRC.
 
please tell me if i'm in the right direction. sorry about the ****ty windows paint drawing

temp_control.jpg
 
also anyone looking at this, don't take this to be correct. i'm asking the more knoledgable people if it is right. so untill some one gives it the ok, don't use it.
 
I have built a very similar unit as the one showed here. I do not believe that a heat sink is required in this situation because of the rather low current being drawn through the SSR as well as the fact that the SSR is designed to be cycled much more frequently then this application would call for. Also since an SSR only has an increased resistance when the circuit is closed ie when the freezer is running there would not be much time for excessive heat to build up. At least that seems to be the case for my freezer; It hardly runs for extended periods of time.

On another note, when using the controller for heat do I need to be worried about the humidity inside of the fermentation chamber?
 
also anyone looking at this, don't take this to be correct. i'm asking the more knoledgable people if it is right. so untill some one gives it the ok, don't use it.

It is similar to my diagram, which I had solicited feedback for a while back. Finally getting around to wiring mine up today. On my diagram, below, the terminal connections go to phono plugs, for cheap and easy disconnects. The "Out" connections for the heating and cooling go to RH and RC respectively. The "Return" connections go to the common ground. I haven't obviously verified that the relays in the thermostat will work yet, but assume that they will. Should have that verified after a little soldering today. Additionally, I have added a connection for a fan, as well. (Didn't label it on this version of the diagram, but "black" is "hot", "grey" is "neutral", and "green" is "ground" for the AC legs.)

One thing that your diagram (and the original one you modified) are missing is the ground connection from the outlets. I am making sure to ground mine, by using a 3-pronged extension cord. For safety, I also added a 15a fuse to my hot leg. Considering that this will run unattended, it is a small addition for a bit of piece of mind. :D



I should have my build done sometime today. I'll let you know how it goes. Everything has been drilled, cut, and test fitted already. Should not take much time to get it knocked together once I get started.
 
ok. i think i get what you have goin on there, but bear with me. i'm really not an electronics guy. what is the outlet on the left for? it looks like your going to plug the fridge and heater in on the outlet to the right? also as for how it is linked to the thermostat, mine says Rh, Rc, Y, G, and W. do you know how that corresponds to your: H out, H return, C out, C return, F out, F return? i'm trying really hard to understand this stuff and i think i almost got it. thanks jmferris!:mug:
 
ok. i think i get what you have goin on there, but bear with me. i'm really not an electronics guy. what is the outlet on the left for? it looks like your going to plug the fridge and heater in on the outlet to the right? also as for how it is linked to the thermostat, mine says Rh, Rc, Y, G, and W. do you know how that corresponds to your: H out, H return, C out, C return, F out, F return? i'm trying really hard to understand this stuff and i think i almost got it. thanks jmferris!:mug:

The other outlet will likely be used to power the transformer.

On my thermostat the RH and RC were the power for heat cycle and power for cooling cycle respectively. The way I wired mine was to put a jumper between the RH and RC.
Then bring the + side of the transformer through the relay (watch polarity on SSR) into either RH or RC and the - side of the transformer went to G the terminal, meant to control the fan relay.
To my understanding there is a heating circuit and a cooling circuit in the thermostat and both circuits have the ability to control the fan. The way it would work in your house would be for the thermostat to send a voltage from the heat or cool circuit to the fan relay in order to start the fan. All i am doing is using the thermostat to ground the control circuit so that the relay will switch.

Im not a circuits expert being a mechanical engineer but that is what I think is happening. So if there are some HVAC gurus on here that can clear it up better feel free to correct me.

Wired like this I can run both heat and cool with my thermostat but I only control one outlet so I would probably have to rethink it if I wanted to heat and cool without having to change what is plugged in.
 
so the the Rh and Rc would be going from the thermostat and to their respective relays? and i wouldnt want them to be jumped so i could control them individually? or its the power coming from the transformer and i would want them jumped so they both get power? then wich ones would go out from the thermostat to the relays? and if i didnt wire two outlets like jmferris then i could just plug the transformer into the wall right?
 
so the the Rh and Rc would be going from the thermostat and to their respective relays? and i wouldnt want them to be jumped so i could control them individually? or its the power coming from the transformer and i would want them jumped so they both get power? then wich ones would go out from the thermostat to the relays? and if i didnt wire two outlets like jmferris then i could just plug the transformer into the wall right?

Well the power goes through the relays and then into the thermostat but yes you seem to get the idea. You would not want Rh and Rc jumped. Just do it like the wiring diagram above but where his says Hout and Cout you would use Rh and Rc and then the return wire would be on G, all the return is is the negative side of your transformer. This will require you to leave the fan setting on the thermostat on auto.

Yes you would be able to just plug the transformer into a wall outlet. But what he has would be nice because your temp controller would just need one plug.

I also had to change the jumper inside of my thermostat to electric heat from gas to make mine work.
 
I think this will work: Referencing the diagram in post #63 - H out would be "W", C out would be "Y" on the 'stat. Leave Rh & Rc strapped together & run to the -5volt supply (Fan, that is "G" on the 'stat) is not needed.
 
I think this will work: Referencing the diagram in post #63 - H out would be "W", C out would be "Y" on the 'stat. Leave Rh & Rc strapped together & run to the -5volt supply (Fan, that is "G" on the 'stat) is not needed.

it's all kinda comin together for me. i think this will work on what i have.

one of the wiring options that came with my thermostat has this

Rh=heat power
Rc=cool power
y=cool contactor
g=fan relay
w=heat contactor.
so the rh and rc get the -5 from the transformer and are jumped so only one wire is needed there. y goes to the cool relay and w to the heat relay?

if so then i'm pretty sure i can do this now
 
any one know if i can use this old samsung charger, for the transformer? it says output: 5 v--0.7A.
 
That should work fine.

I like what junkster said about using W and Y rather than G for the 2 SSR controller.
 
i do to. i don't know much about electronics and thats seems to be what the instructions that came with the thermostat said.
 
also please post some pictures when you get it done!

Sadly, I am going to have to wait at least one more day to finish up. The junction box itself is built out, and the "always live" side works well. In my infinite wisdom to go with phono jacks in the enclosure, I seem to have forgotten the fact that it commonly uses a shielded cable. I can't find any dual-stranded cables in my big box o' crap, so I'll have to make a few. It would be a PITA to otherwise hook up to the thermostat. ;)

This is what it looks like, as it sits right now. Still have to label my external connections and run the wires to the thermostats. Should only need another ten minutes to solder and heatshrink the new cables once I get the jacks tomorrow. Forgive the crappy phone-quality image:



So, tomorrow it is off to Rat Shack to pick up some phono plugs so that I can run a dual-stranded wire off of each of them. At least since I have yet to have the relays go hot, I can proudly say that I haven't burnt down the house today. :mug:
 
ok. another dumb question from my non-electricity understanding ass. i bought two relays. figured i needed the DPDT the one i got is eight pin. is this right? after reading a bit on relays it seems like i should have gone with the SPDT. i went to radio shack and they didn't have any that looked like the ones from the OP. please help!

and jmferris, don't forget about the update pics!
 
ok. another dumb question from my non-electricity understanding ass. i bought two relays. figured i needed the DPDT the one i got is eight pin. is this right? after reading a bit on relays it seems like i should have gone with the SPDT. i went to radio shack and they didn't have any that looked like the ones from the OP. please help!

and jmferris, don't forget about the update pics!

The OP used solid state relays, are the ones you bought SSR or coil type?

When I built mine, I only used one SPST coil relay, (You would use two if you were cooling and heating. I was only cooling).

The SPST I bought has 4 terminals and is in the "normally open" position, so that when power is applied to the coil, the circuit is closed, turning on the fridge.
 
mine were coils. i didn't know any better. and i bought the DPDT, they were eight pin. can i still use these? or should i take them back to radio shack?
 
You can still use it, its just not necessary.

relaydpdt.gif


See in this diagram, each pole is normally contacting one throw or the other.

When voltage is applied to the coil, each pole switches, and contacts the other throw.

You only need one of those poles, and one of these throws, meaning you will have a lot of unused pins.

Not a problem, just not necessary.
 
ok. so what i want to do is connect the bottom two, that are turned perpendicular to the others, to the thermostat and transformer, then connect the wires from the wall to the outlet through two of the other poles? does it matter which ones i use? also it looks kinda little to be running 120 volts through.
 
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