Discussion in 'Homework Help' started by alim, Feb 2, 2011.

  1. alim

    Thread Starter Senior Member

    Dec 27, 2005
    Hi I have a vtech cordless phone which uses AC voltage to the device . I am looking for a method to install a standby power in the event of power failure. I had other cordless phones which used DC sources, and I would use batteries thru switching diodes, and that was OK. In this case I connected a suitable DC source to to the point where the charger power goes to charge the phone, but after sometime the phone gets hot. If you disconnect the power with the DC on, the phone would stay on .If power goes off and the DC was not on and you subsequently connect the DC, the phone would not work. One idea was to connect a relay to switch on the DC as soon as power goes, but this would entail powering the relay all the time until power goes off, which would work, but is there any other solution. I would be glad to hear. Thanking you. alim.