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Detection of AC voltage

  1. Jan 25, 2012 #1

    i wanted to control one of my home appliances basically to switch it off after some time (as of now 10mins). i got stuck up at the first step itself where i want to know whether the switch is ON i.e. i wanted to detect whether AC input is on. So my basic question is how to detect a 230v 50hz AC signal and based on the presence of the ac signal i can start some 555 timer circuit and control the switch. i wanted a very low cost circuit i thought of some 230v relay, can i use it?

    Thanks in advance,

  2. jcsd
  3. Jan 25, 2012 #2
    Yeah you can use a relay. But make sure you ground your stuffs properly.
    Relay has pin configurations which will tell you which two pin is stuck together when its ON or OFF. You can use multimeter set to ac to detect ac.
  4. Jan 25, 2012 #3


    User Avatar

    Staff: Mentor

    It doesn't sound like you have much experience working with AC Mains circuitry. You need to find some pre-made modules that you can use for this appliance switching application. The shock and fire hazards are too great for you to be trying to home-brew a circuit and build it.

    Look at Appliance Switch Modules like these:


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