Battery back up

Discussion in 'General Electronics Chat' started by jerrymyersmills, Apr 27, 2011.

  1. jerrymyersmills

    Thread Starter New Member

    Mar 22, 2011
    i have ordered 1 channel opto-isolated IO relay board for a project work.I want install a siren that will be backed up with a 12 VDC car battery(battery backed) so that the siren will sound in the even of power failure.
    I Have read that it possible to achieve this by extending the alarm leads to the N/C contacts as there is continuity in NC contacts when the coil is de-energized
    .Is it possible to achieve this end?
  2. BillO

    Distinguished Member

    Nov 24, 2008
    Why not throw up a circuit diagram that we can have a look at? With no frame of reference, its difficult to figure out what you mean. A proposed circuit diagram would help a lot.