ULN2803 to drive 24VDC relay for 24VDC solenoid valve

Discussion in 'The Projects Forum' started by pr123, Oct 15, 2015.

  1. pr123

    Thread Starter Member

    Mar 13, 2015
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    Hi,
    I'm using a ULN2803 IC to drive a solenoid valve 24VDC throughy relay (DIN rail mountable with base) which is rated for 28VDC,10A. How can i be sure this will work? what parameters should i calculate for this? i have worked with ULN before but it was for 12VDC PCB relay and 12Vsolenoid.
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,504
    380
    hi,
    The ULN will work at 24V without any problem.
    I would require the 24V relay coil resistance needs to be specified, I would estimate a resistance of around 800 ohms.
    Don't forget to connect the ULN's common diode pin to +24Vdc
    E
     
  3. pr123

    Thread Starter Member

    Mar 13, 2015
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    0
    yes, ULN connection COM has to be connected to 24VDC and 9th pin to GND. Resistance is not mentioned exclusively but coil current mentioned is 56mA .
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    At 24V and 56mA thats ~428 Ohms.
    The ULN should be OK
     
  5. pr123

    Thread Starter Member

    Mar 13, 2015
    30
    0
    ok thank you
     
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    Why use the relay? Cant the ULN drive the solenoid coil directly?
     
    MaxHeadRoom likes this.
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