power circuit with battery needed

Discussion in 'The Projects Forum' started by router_help, May 15, 2008.

  1. router_help

    Thread Starter New Member

    May 15, 2008
    I need a circuit to provide the following for my wireless router in the loft that siezes up when it has a short power glitch, a power on delay circuit with a battery backup and charge circuit.

    I have seen several 555 timer circuits that will power delay the output via a transistor, but my knowledge is way to low to build the battery charging/control parts or integrate the whole thing. As I understand it, the variable input could be controlled by a regulator, but would it need one for the input to control battery charging and one for the input to the 555 timer circuit or more?

    Input up to 18 Volts so a wide range of input voltages can be used (6 to 18 or even 24?) I want it to be useful for other people, so a wide range of input would be good.

    Output 5 Volts @ 1 Amp, most routers are fairly low power.

    The battery is to provide a backup power source when the input power fails, the battery size is variable so I, or anyone else who reads, could use whatever was available, from a small cell to car battery. Ideally the circuit would cut the output when the battery voltage falls to prevent damage to the battery. Also it would prevent the battery from supplying the circuit if it didn't have enough energy and it needs to trickle charge the lead acid cell. I don't mind the cell voltage, please specify.

    When the output has failed because of battery exhaustion and/or input power failure, the circuit should delay the switch on of the output by about 30 seconds when the input is restored so that my router doesn't lock up.

    Thanks for looking.
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    If you simply seek to have a solution to the router problem, there are several uninterruptable power supplies on the market. You would be quite hard pressed to build one for as little as you could buy one.

    If you are primarily interested in building an interruptable power supply as a project, you will need to begin by specifying input range as well as output, and by selecting a specific battery type.
  3. router_help

    Thread Starter New Member

    May 15, 2008
    Thanks for the quick reply.

    I want a small unit that takes a low voltage supply, not mains ac. If it could be powered by the routers existing supply which is 5 volts 2A (not very efficient), that is a bonus, but I thought that the battery would need a higer charge voltage. The battery should be something common like a 4.5Ahr 6 volt SLA if a circuit could be designed to would work with it or 7.2Ahr 12 volt SLA cell. This isn't intended to run the router through an extended power outage.

    Sorry if I was too vague, I was trying to be helpful by specifiying a wide range in the input of up to 18 or 24 volts so it could be supplied by power over ethernet as it's in the loft.
  4. good by

    New Member

    Dec 31, 2008
    Allaptob battery containing several small batteries of shipment, the amount of voltage to Oanah with each sincere gratitude