Relay confusion

Discussion in 'The Projects Forum' started by Davemarz, Feb 11, 2013.

  1. Davemarz

    Thread Starter New Member

    Feb 4, 2013
    Kind of new to relays and I'm hoping you all can help me out.

    I have a 12 VDC circuit total draw is about 1 amp. I am using two relays in series Digikey PN PB1550-ND.

    If you look this item up, digikey describes its turn on voltage Max as 9VDC and no minimum is listed. However, pulling up the manufacturer's data sheet it lists the operating voltage as 9VDC.

    So, did digikey describe this incorrectly??
    Can I run 12 VDC through this without releasing any magic smoke??

    Overall I feel pretty good about the circuit but if you would like to see it I have attached a copy.

    Any help is greatly appreciated.
  2. k7elp60

    AAC Fanatic!

    Nov 4, 2008
    I think the normal operating voltage for the relay is 12VDC. I looked at the data sheet and also I have a catalogue that lists the series. DC relays have a pull-in voltage that is less than the operating voltage. What the data sheet implies is that the maxmum voltage necessary to energize the relay is 9V, it may energize at a lower voltage, but the normal operating voltage is 12VDC. So you should be fine.
  3. Davemarz

    Thread Starter New Member

    Feb 4, 2013

    Thanks for the quick reply. I feel better now. :D
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
    Don't you have this backward? Usually the "pull-in" voltage is higher than the "hold-in" voltage.
  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
    This is true for the type of mechanical relay used.

    However he meant the datasheet parameters "operate voltage" and "rated voltage". Operating voltage is 9V and rated voltage is 12V. It doesn't say if it will pull in at 9V or if it will hold at 9V. I assume it will pull in.

    @OP There are no resistors for the LEDs in your circuit.
    Last edited: Feb 12, 2013
    shortbus likes this.