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Temperature controlled relay (help needed for noobie)

Former Member

Hello, my name is Aisha this is my first post and I am excited to get into the community.


I live in a studio apartment with my wife. The entire apartment is on a 15amp breaker so we have to be careful about power use. We find if we run the A/C and cook something in the kitchen the fridge will kick on more often and trip our breaker. We have a blower to pull hot air out of the kitchen and I would like to use an arduino to turn it off and on based on the temperature.


I have:

 

an arduino uno

a tmp36 temperature sensor

a 5v arduino relay module

a breadboard and leads

 

I want to do this not only the right way and the best way with what I have available. I have used the arduino to switch the relay using the blinking LED code from a kit I got. I have wired up the sensor and read readings off of it.

 

 

The tutorials I find online say I should connect it to 3.3v and also AREF to 3.3v when I do this I don't get 3.3v in my serial monitor like the tutorials say but 1.5 (average). I am left lost as no tutorials show how to do this without an LCD screen and with a relay module. I don't need to monitor the temperature after I have it set properly once so an LCD is unnecessary (though I would not mind being able to add on in the future.)

 

I plan to put the sensor on a cable, are there limits to how long a cable can be for this sensor? I was planning on using cat5 cable.

 

So far all of my experiments with arduino involve copy pasting code and maybe modifying a couple lines that are clearly labeled or that a tutorial has told me to edit. I have 0% skills and about as much understanding and confidence in coding anything let alone a micro controller.

 

I have seen people adding things like data logging to increase accuracy of readings and delays to keep the switch from tripping like crazy but again I'm still struggling with the hardware and code is not at my level yet.

 

Hopefully there are people who can help me out. I know this is super easy for anyone who knows how to use and code arduino, I just need some help getting my first project finished.

  • aishalove

    First off, programming is not "super easy" as you say. I have done this most of my life and the biggest headache is to fix broken code. Even I break and fix my own code. I suggest read some about coding logic and play to learn.Start off with a blinking LED for example.

    Next make it blink slower the first time and faster the second time, Make it blink 4 times fast and 2 times slow. Each exercise build your knowledge and confidence, If it does not work the way you think you planned, run through the code with pencil and paper to determine why.

    Next add a button or two to start or change the blinking. You may think this is silly, but try to follow and you will learn more than you expect.

    Clem

  • aishalove ,

     

    as Clem says you are not starting on something like "follow the instructions and put the Lego pieces together". A too wide simplification and too wrong estimation vision of what "Arduino" is, frequently creates the illusion that things are simple. Try seeing your small board as a Micro-Controller, that is a small yet powerful micro processor where you can put your hands on. This means that to move from a potentially doable idea to the "stuff in your hands" there is a passage far from to be something silly. Implies coding but not only: a minimal electronic knowledge, components choice and more other not silly aspects are involved.

     

    In my opinion, here you can find a lot of helpful hints and support but the thing that it is not the worth to expect (IMHO) is to find what you need ready to copy and paste or to take and solder image

     

    Keep us informed and good luck.

  • aishalove

     

    Clem and Enrico have given you sound advice image.

     

    For what it's worth, I have 2 basic rules when I am developing a project:

     

    1. Start small with something that should work - an example from the Arduino Library, a Tutorial, etc, and make it work for you. Then develop it, a little bit at a time, until it does what you want.
    2. Use output to the Serial Monitor to tell you where you are in the program and what value(s) you have read or calculated.

     

    Good luck, and don't be afraid to post new questions about more specific problems image.

     

    Neil

  • What had not been said yet is the issue of driving mains with an arduino relay board.

     

    They are not all created to handle mains . Even if the physical elay is capable. The board may not be and mistakes with mains can be rather unforgiving

     

    Don't know you expertise with mains control but if not much then seek advise here before you attempt it

     

    You can of course go right ahead and drive the relay board from the ardiino , just don't connect mains unless your sure.

     

    Many of these boards are designed for only 24v but still have 240v relays on them. So don't think is still safe just because the relay says so

  • in reply to Robert Peter Oakes

    Good point, Peter. I was suckered into buying such a relay board ( such a pretty blue colour; matches the Arduino!! ) early on in my Arduino experiments - I haven't used it to switch 240V !

     

    Neil

  • in reply to neilk

    I haven't used it to switch 240V !

    I would suggest using a Solid State Relay when it comes to 230v.

     

    The advantage is that some include a LED on the input side, and take no more energy that a LED.

     

    aishalove

     

    I found these two links for temperature controlling a relay.

    http://www.electroschematics.com/8998/arduino-temperature-controlled-relay/

    Make Your Own Temperature Controller with an Arduino

     

    They should help you with the code.

    I do have a sketch using DS18B20 One wire temperature sensor if you want to swap measuring devices.

     

    Mark

  • in reply to mcb1

    Mark - I particularly like the one which uses the Maplin remote control power socket - Note, others types are available!

     

    It has the clear advantage of eliminating ANY need to work with mains voltages - it's all been done for you and is all neatly locked away.

     

    I already use some of these remote control power sockets, with their original control, to obviate the need to crawl under my desk to switch off my PC etc

    Very very useful at my age!

     

    Neil

  • Thanks for all of the feedback. I came into arduino with the belief that it was super easy and even if you never wanted to code you could just grab other people's code and do minor tweaks. this is the impression I get from most arduino enthusiasts.

     

    I would love to learn to code but have no idea where to start, though I am going to look into online resources.

     

    About my project, the relay I have is this one

     

    Amazon.com: Tolako 5v Relay Module for Arduino (Works with Official Arduino Boards): Computers & Accessories

     

    It says "can control 220v AC load, I am in the US so I only need it to handle 120v ac

     

    When I have some time I am going to work with some of the code a couple of you have linked to and see what I can accomplish.

  • in reply to Former Member

    Aisha

    We've said this many times before on the forum ...so you'll excuse me for sounding a little short.

    image

     

    You can search within the forum and find some other replies as well.

     

     

    Mark