Connect with us

Need help with a circuit

Discussion in 'General Electronics Discussion' started by ChickenNuggets, Sep 30, 2016.

Scroll to continue with content
  1. ChickenNuggets

    ChickenNuggets

    2
    0
    Sep 30, 2016
    I have two circuits, Circuit A that runs at 5 volts and Circuit B that runs at 48 volts. It is basically an arduino that is connected to a relay connected to power supply connected to fans. However when Circuit A turns off, Circuit B (the fans) are still running. I know that it is not the code of the arduino, and I do not think that it is the arduino is the problem at all.
    How do I make it so when Circuit A fails, Circuit B turns off as well, so it is just not running "out of control" per se.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,582
    2,360
    Nov 17, 2011
    A schematic could be helpful ;)
    How is the aduino controlling the relay?
    What does "when Circuit A fails" mean? In which way does the circuit fail, how does the failure show on the output controlling the relay?
     
  3. ChickenNuggets

    ChickenNuggets

    2
    0
    Sep 30, 2016
    I don't have one. The arduino is controlling the relay by having it be on for 3 seconds then off for 2 seconds. When I unplug the battery to the arduino the fans are still running. I need to make it so when the arduino gets turned off or fails, the fans stop too.
     
  4. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    If the fan is still running when the arduino is powered down then you have the fans connected to the normally (NC) closed relay contacts.

    Chris
     
    HellasTechn likes this.
  5. HellasTechn

    HellasTechn

    1,542
    214
    Apr 14, 2013
    That is correct Chris.

    You need to change your fan wiring to the Normally open contacts and then alter your arduino code so that it will disengage the relay when it was supposed to "engage" it and to "engage" it when it was supposed to be "disengaged"

    In other words make the output of arduino controlling the relay go high when it would be low and low when it would be high.

    does that make sense ?
     
    CDRIVE likes this.
  6. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    If it is cycling correctly ON - OFF while the Arduino is running then it's unlikely that you need to change your code. Not from the description above, that is. Just change your wiring to the Normally Open (N/O) contacts of the relay.

    Chris

    Edit: I just noted that your ON - OFF times aren't symmetrical. If the timing sequence is now correct then Constantine is correct. You'll have to change your code too.
     
    Last edited: Sep 30, 2016
    HellasTechn likes this.
  7. HellasTechn

    HellasTechn

    1,542
    214
    Apr 14, 2013
    That is why i suggested him to alter the code :) to keep timing !
     
  8. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Yes, that's why I corrected myself. "CYA"! :p

    Chris
     
  9. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    Well, it doesn't have to be the use of NC contacts. It could be that whatever circuit is driving the relay needs to be either pulled up or down to open the relay.

    Bob
     
  10. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    Did you miss this?

    Chris
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-