By using 12v relay, how to connect/power up 24v DC devices?

Discussion in 'Digital Circuit Design' started by vallikkv, Jul 29, 2016.

  1. vallikkv

    Thread Starter New Member

    Jul 29, 2016
    3
    0
    Hi All

    I'm software test engineer, Like software automation, we also trying to automate the hardwares. We have an IO board which is accessible via web, and through web we can switch ON /OFF (ie NC & NO) the relay pins of the IO Board.

    Now I want to connect a 24V device in this IO board, which is having 12V relay. And I'm expecting to power on /off the device using IO board web. (Say switch off/on the PIN 1 of the IO board)

    I believe its not possible to connect 24V line (+ or -) directly to the NC or NO pins of the relay.
    How to achieve this solution for this? Some peoples suggest me to use 24 v relay to connect to 12v relay.

    Im not sure about this? and what type of relay supports this to buy?

    Need help on this topic

    Thanks
    Vallinayagam.K
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,779
    932
    The contacts of a relay are not normally connected with the coil which toggles it.

    A 12 volt relay is operated by a 12 volt source, but it can switch low level audio or 120 volt AC, as long as the contacts are rated for that power level.

    You will operate the 12 volt relay with a 12 volt source, and you CAN put 24 volts on the contact pins to be sent to your 24 volt equipment.

    Consult your relays data sheet for ratings and connection pin out
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,513
    2,369
    You do not connect the power + & - to a pair of relay contacts, they are used in series with a load of some kind to control it.
    We Need an idea of the circuit you need
    Max.
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,779
    932
    Example datasheet
     
  5. vallikkv

    Thread Starter New Member

    Jul 29, 2016
    3
    0
    Can I connect the circuit like attached?
     
  6. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,142
    201
    Your I/O board should tell you the contact ratings of the relay. Sometimes the AC and DC ratings are different.

    If your manual doesn't, look up the p/n of the relay and find it's datasheet.

    Sometimes contact protection is required..
     
  7. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,518
    1,247
    Fortunately for you, that is incorrect. The ratings for the relay contacts can be significantly different from the ratings for the coil. many relays have the contact rating stamped on the cover or on a label. Can you post a photo?

    ak
     
  8. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    Your circuit basically is correct, I just labeled the voltages, and you have to care about the current ratings of contacts.

    RelayCircuit_vallikkv.gif
     
  9. vallikkv

    Thread Starter New Member

    Jul 29, 2016
    3
    0
     
  10. #12

    Expert

    Nov 30, 2010
    16,261
    6,767
    A lot of variation on the load depending on the voltage and inductance. That's what the datasheet is for.
     
  11. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,513
    2,369
    Two more useful references on relays.
    Max.
     
Loading...