Need Help on semi automatic water level controller using 555 in bistable mode

Discussion in 'The Projects Forum' started by edaxpei, Nov 17, 2015.

  1. edaxpei

    Thread Starter New Member

    Nov 17, 2015
    6
    0
    I have build an semi automatic water level controller using 555 in bi stable mode i.e. it will not turn ON automatically (one should have to press a button to start) but will turn OFF automatically when water level is high.So I have directly connect the VCC to PIN 2 through a push to OFF switch.My problem is that the pin 3 goes high automatically without pressing the button when power supply fluctuate(turn on off) for atleast 3 times.Plz help
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Circuit diagram please, we dont do mind reading...
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    A high-value capacitor on pin 4 would normally be used to keep the 555 reset (pin 3 low) at power-on. Do you have one?
     
    edaxpei likes this.
  4. edaxpei

    Thread Starter New Member

    Nov 17, 2015
    6
    0
    IMG_20151117_171920.jpg
     
  5. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Ok how do you want it to work, do you want it to detect when the water is low and switch on automatically, or manually?
     
    Last edited: Nov 17, 2015
  6. etech7

    New Member

    Jun 9, 2015
    29
    0
    If you want to trigger 555 you should connect PIN 2 to ground (trigger pin is active low). Put a high value resistace (10K-100K) between PIN 2 and ground. Normally that switch will connect the PIN 2 to high (Vcc). When you press that sw, it breaks the contact between Vcc and PIN 2 then PIN2 will connetected to ground via high value resistance thus making PIN 2 low and trigger the 555 timer. Reply with feedback.
    :)
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    Try this arrangement, which should avoid false triggering at power-up and with power glitches of a couple of seconds or so :-
    555-bistable.PNG
    A float switch would provide the 'stop' signal.
     
  8. edaxpei

    Thread Starter New Member

    Nov 17, 2015
    6
    0
     
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    The OP has specified manual start (non-automatic).
     
  10. edaxpei

    Thread Starter New Member

    Nov 17, 2015
    6
    0
    I do not want to detect the low level of water by this circiuit, But it will detect High level of water.The strat will be manual.
     
  11. edaxpei

    Thread Starter New Member

    Nov 17, 2015
    6
    0
    I have almost done by the circuit i have given above but my problem is that WHEN MAINS SUPPLY FLUCTUATE THE PIN 3 OF 555 AUTOMATICALLY GOES HIGH.
     
  12. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    No surprise there.
    Did you try my post #7 circuit?
     
  13. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,005
    745
    Have you modified your circuit as per post#7, pin 2 needs a pull up resistor to prevent false triggering???
     
  14. etech7

    New Member

    Jun 9, 2015
    29
    0
    One thing that i am not understanding... why are you using such a supply that fluctuates? :confused:
     
  15. edaxpei

    Thread Starter New Member

    Nov 17, 2015
    6
    0
    I do not use a supply that fluctuate,but here(in my place) the power supply is not availabe continously.Thats why i have to take this condition.So that the water pump does not start automatically.
     
  16. RRITESH KAKKAR

    Senior Member

    Jun 29, 2010
    2,831
    89
Loading...