12v Circuit that's Closed during Daytime and Open at Night

Discussion in 'The Projects Forum' started by misterranger, Aug 6, 2008.

  1. misterranger

    Thread Starter New Member

    Aug 6, 2008
    I need to create a timer switch that can run off 12v or 5v dc battery powered circuit. The circuit will likely carry 2.5 amps max. I would like it to be open at night and clsoed during the day. The device using the power in the circuit is dumb and can't turn itself off at night. So I need to open the circuit so it doesn't run my battery down at night.
  2. HarveyH42

    Active Member

    Jul 22, 2007
    You need a light activated switch. Don't have anything handy for 12 volts 2.5 amps, but shouldn't be to hard to do.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    Perhaps you could turn a MOSFET on with a photovoltaic cell.
  4. mik3

    Senior Member

    Feb 4, 2008
    Use a comparator IC (op-amp), an LDR and a few resistors to make a dark detector. Then with this drive a relay to control your circuit.