My First Relay Project

Discussion in 'The Projects Forum' started by Nate_Bro, Mar 2, 2011.

  1. Nate_Bro

    Thread Starter New Member

    Mar 2, 2011
    18
    0
    This is my first post here, looks like a good site!

    well I'm wanting to build a relay system for my reef aquarium...

    I have got an aquarium controller unit, but I need more...

    right now I have a lot of things I need turned on and off 24 hours a day..

    I have a 4 outlet unit right now with my controller, but I need about 16+ more outlets for better automation.

    so this is my Idea,
    I need to control 120v outlets by use of relays, and a controller ether a computer, or a micro-controller.

    I will need to turn the relays on and off by float switches, temp sensors, and photo sensors.

    so if you could help me find some model numbers, some circuits, and input, that would be great.

    I have done a lot of car and house wiring, also I have done a bit of computer programming over the years. I'm not so good with complex circuits so please bare with me :)

    thanks again!
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    You may want to look at the LabJack U3:
    http://labjack.com/u3

    At ~$120 it may be overkill I'm pretty sure it would more than cover your needs, although you'll also need a relay for each switched outlet. The good thing is that you'd gain complete recording and control capabilities as long as you can dedicate a computer to that.
     
  3. Nate_Bro

    Thread Starter New Member

    Mar 2, 2011
    18
    0
    I actually was looking at that unit, but the price tag was a little more then I was looking for... also I want to learn a little about circuit boards, so if there is a way to make my own...

    I have been looking around, and seems like I can get relays for about $1-3 each, and sensors for about $1-2 each....

    If all else fails I can buy another aquarium controller ($130) that would do a lot that I need, but I really like DIY projects and it gives me something to do..

    thanks again for the input!

    also I have been looking at a lot of relays, what specific one am I looking for?

    I'll be running 3-5-8 amps on diff ones, also I'm going to use 120v

    thanks again!
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Arduino mega, a real time clock (with its associated crystal/resistors), 16 NPN transistors, 16 base resistors for the the transistors, 16 relays, 16 diodes and a 12V power supply. Have fun...
     
  5. Nate_Bro

    Thread Starter New Member

    Mar 2, 2011
    18
    0
    Arduino mega, Great Deal!!!!!!!!! thanks!


    also dose this sound ok for the relay? I'll be useing less then 10A
    ______________________________________
    Manufacturer: TYCO ELECTRONICS / POTTER & BRUMFIELD Part Number: 17M3044 Manufacturer Part No: T7CS5D-24 RoHS Compliance : Yes
    Description
    • POWER RELAY, SPDT, 24VDC, 12A, PC BOARD
    • Relay Type:Miniature
    • Coil Voltage VDC Nom:24V
    • Contact Current Max:12A
    • Contact Voltage AC Nom:120V
    • Contact Voltage DC Nom:28V
    • Coil Resistance:1600ohm
    • Contacts:SPDT
    • RoHS Compliant: Yes
     
  6. Nate_Bro

    Thread Starter New Member

    Mar 2, 2011
    18
    0
    would one of these work for the RTC, if so what would be better for what I want to do?

    DS1307 Real Time Clock breakout board kit: +-2 sec a day
    or
    ChronoDot RTC: Ultra-precise
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    I'd pick a 12V relay (coil voltage) then you can use the same 12V power supply for the relays and to power the Arduino.. and yes the DS1307 breakout is just fine to use.. (I'm using it too)

    Just make sure you power supply has enough current to power multiple relays at one time (as many as you will have on at 1 time)

    and if you get DPDT relays you can switch 2 devices on at one time..

    and remember line voltage is dangerous and can kill you. Please use caution and ensure that you have proper clearances/insulation to prevent shocks/fires,etc...

    There is a bunch of information on how to switch relays using the arduino.. (google and the arduino.cc site/forum is your friend) You will need a transistor or optocoupler,etc. as the arduino can't provide enough juice to power the relays directly from the micro.
     
  8. Nate_Bro

    Thread Starter New Member

    Mar 2, 2011
    18
    0
    sounds good,

    I'll get some things together, thanks for all your help! I think this project if off the ground now!

    thanks for telling me about the wires can kill, I'v had my heart stopped 2 times by electrocution, once on 210v (arc welder) and once installing a 4000w amp in a running car, while it was all hot, its not fun! you think I would have learned the first time....
     
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