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

Thread Starter

edaxpei

Joined Nov 17, 2015
6
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
 

Dodgydave

Joined Jun 22, 2012
8,467
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:

etech7

Joined Jun 9, 2015
38
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
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.
:)
 

Alec_t

Joined Sep 17, 2013
10,432
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.
 

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Thread Starter

edaxpei

Joined Nov 17, 2015
6
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.
 

Thread Starter

edaxpei

Joined Nov 17, 2015
6
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.
 

Thread Starter

edaxpei

Joined Nov 17, 2015
6
One thing that i am not understanding... why are you using such a supply that fluctuates? :confused:
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.
 
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