Cute, simple and useful circuit

Discussion in 'General Electronics Chat' started by marshallf3, Feb 9, 2011.

  1. marshallf3

    Thread Starter Well-Known Member

    Jul 26, 2010
  2. cumesoftware

    Senior Member

    Apr 27, 2007
    This is a nice, yet simple idea for a circuit! Thanks for sharing!
  3. someonesdad

    Senior Member

    Jul 7, 2009
    Great idea! But I think it would be simpler to use the wall wart to power a PC-mount 5 volt SPDT (i.e., form C) relay and connect the LEDs to the batteries through the NC contacts. Then when the power goes out, the batteries get connected to the LEDs. I'd just use two AAs in series and eliminate all the other parts except for the LEDs and their resistors.

    Total parts = perf board, LEDs, resistors for LEDs, relay, batteries & battery holder, and wall wart (switch optional).

    I'm going to make dang sure nobody from my family sees this, as then I'd have to make a bunch of them. :p

    Of course, it can be made fancier too. I might want an optical sensor to make sure it wouldn't come on when the power failed during the day.