12v UPS relays Trigger, 1 ~ 11v no trigger

Discussion in 'General Electronics Chat' started by Jacquesl, Aug 24, 2007.

  1. Jacquesl

    Jacquesl Thread Starter Member

    Joined:
    Dec 9, 2006
    Messages:
    29
    Hi,

    I’m busy with some UPS circuit and I need it to switch a couple of relays on then the power is back.

    http://www.allaboutcircuits.com/vol_3/chpt_7/5.html

    [​IMG]


    Can I replace the triac with a transistor because I don’t want to let the relays on until the power is down,

    I basically want a easy method to trigger a couple of relays then the mains is back, currently I’m using a 10volt reformer on a 12v relay and if the mains drop the relay drop very fast, but the transformer is to small for 3 relays and then using 3 relays I hear a buzz sounds because it probably under power, in my circuit I have a regulated power supply and a small crap 10 – 11volt power supply just to do the relay work and the regulated power supply with huge caps is for the timer section and some other components


    Purpose needed for:

    1 ~ 11 volt - no trigger
    12 volt - trigger


    thx
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