Choosing Relay

Discussion in 'General Electronics Chat' started by edliu, Mar 4, 2011.

  1. edliu

    Thread Starter New Member

    Feb 22, 2011
    Hi All,

    I have a problem on choosing my relay. I need a DPDT relay. The relay is controlled by a Arduino and the output is being drived by a 27V and 5V 5A current to the load.

    However, I do not now how to choose the correct relay. I some datasheet and I do not understand some of their purpose. Can someone please advise?

  2. Jaguarjoe

    Active Member

    Apr 7, 2010
    What do you mean, "27v and 5v"? 5 amps is the load current being switched? The Arduino will only supply about 20ma of current by itself. You will probably have a hard time finding a 20ma/5v coil relay that will switch 5 amps. Look into using an interface transistor or MOSFET in between the Arduino and a relay. This will make finding a relay easy. Look in any microcontroller tutorial and there should be an interface circuit to use. Picaxe manual 3 has one for sure.