water level indicator and siren

Discussion in 'General Electronics Chat' started by getzme4u, Aug 18, 2011.

  1. getzme4u

    Thread Starter New Member

    Aug 12, 2011
    hello everyone
    i have made water level indicator based at cd 4066 there we put 4 metal screw and wired to our kit.
    in that one is +12v supply and rest three are inputs. and at last one we use relay for loud siren.
    but there we are facing trouble with earth problem.there earth making flicking in realy and relay flicking very fastly and we are feared also that is that current we leave in water current can make any trouble when we use water or get any shock.
    here i am attaching a file for this but here after bc148 i used a 12 v small relay for siren so this realy is getting flicked.
    please solve my problem
  2. SgtWookie


    Jul 17, 2007
    Piezo buzzers are a very small current load. A relay takes a lot of current to energize. You will probably need a MOSFET transistor instead of a standard bipolar transistor. You might be able to use a Darlington transistor instead.

    Since you have not told us what the electrical specifications of your relay are, we can't do much more to help you.
  3. iONic

    AAC Fanatic!

    Nov 16, 2007
    A non-power-hungry (no relay) version.


    I don't believe the NPN transistors have to be as specified, any general purpose transistor should do like the
    2N3904, 2N2222,...

    Also: A 390 Ohm series resistor in line with each LED is needed also.
    Last edited: Aug 18, 2011