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battery fast discharging in switching circuit

Discussion in 'Power Electronics' started by shrikanthkp, Sep 2, 2013.

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  1. shrikanthkp


    Sep 2, 2013
    I build a switching circuit for RF transmitter.Here NPN(BC547) transistors base gets switching signal from microcontroller & collector connected 9volt 6f22 battery through small resistor Emitter grounded directly. here 9volt sugar cube relay used & relay output (N/o)given to transmitter circuit.
    Here battery gets drained (9 volt to 5 volt) within 24 hours without sending any switching signal from microcontroller.The circuit just ON condition only.
    I want overcome battery discharging problem.As per my expection battery should come atlest 6 months.
    Please help me.
    Pl.looking forward valuable replies with great thanks.
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Can you draw us a circuit diagram?

    If you are powering the relay continually, I have no doubt that a small 9V battery will die very quickly.

    One alternative is to switch the load with a mosfet which would remove the need for a battery (but require a common ground and a DC load to be switched).

    Another alternative (especially if the load is always on, and only turned off infrequently -- say to reset it) is to use the relay's NC contacts to power the load and to use the battery to apply power to the relay to turn the load off.

    There are other options, such as an optocoupler and a triac (for an AC load), and possibly even an optocoupler and a mosfet for a DC load without a common ground.

    More information is required...
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