Connect with us

Semi Automatic water overflow controller

Discussion in 'General Electronics Discussion' started by Prashant Zingade, Sep 8, 2016.

Scroll to continue with content
  1. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    Hi All,

    I created latch circuit to start water pump manually and stop Automatic, in that I'm facing issue when i touch probe of wire by hand circuit start Automatic. Im using 12v 1Amp SMPS power supply.

    How to reduce sensitive ?

    Please help.

    Circuit diagram attached.
     

    Attached Files:

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    11,006
    2,506
    Nov 17, 2011
    SW 1 is for manual start,
    SW 2 is for automatic stop, right?
    Try adding a capacitor from tha base of Q1 to ground (0 V) to reduce sensitivity to noise
     
  3. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    Thanks for reply.
    Yes. Sw1 to start n sw2 to auto stop.
    Ok i will try it and get back to you.
     
  4. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    Also I notice that when I use 9v 500ma power supply it work good. But when I use 12v / 1amp supply its become more sensitive.

    What will be the value for capacitor to Q1 base and ground.?
     
  5. Alec_t

    Alec_t

    2,927
    797
    Jul 7, 2015
    I would suggest adding a pull-down resistor of ~100k between Q1 base and ground to ensure the base is never 'floating' at an ill-defined voltage. Q2 could benefit from a ~100k pull-up resistor to the +ve supply to prevent possible leakage currents from causing spurious setting of the latch.
     
  6. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    Ok thanks i will try it.
     
  7. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    Capacitor is not required between Q1 base and ground ?
     
  8. Harald Kapp

    Harald Kapp Moderator Moderator

    11,006
    2,506
    Nov 17, 2011
    Q1 is pulled down, weakly though, by R2 and RL1. An additional resistor of ~100 kΩ may decrease sensitivity.
    A capacitor will reduce sensitivity to noise (AC).
    You may have to add both. Give it a try and play around with values to optimize the result.
     
  9. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    Added both 100k and 10uf/25v capacitor between base Q1 and ground. Circuit latch for 2 second and discount again.

    Pl help.
     
  10. Alec_t

    Alec_t

    2,927
    797
    Jul 7, 2015
    Did you also add the pull-up on Q2 base?
     
  11. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    No that pull up not tried yet. I will try and update .
     
  12. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    It is working now. Thank you.

    One more help. Can we add dry run protection in this circuit so that water pump will shut-off when no flow of water in pipe.
     
  13. Alec_t

    Alec_t

    2,927
    797
    Jul 7, 2015
    You could add a 'supply missing' switch in parallel with SW2.
     
  14. Prashant Zingade

    Prashant Zingade

    9
    0
    Sep 7, 2016
    I did not get you for 'supply missing switch'. Will you please elaborate.
     
  15. Harald Kapp

    Harald Kapp Moderator Moderator

    11,006
    2,506
    Nov 17, 2011
    A switch that is activated when there is no supply of liquid to the pump. this switch in parallel to SW2 will stop the pump when the liquid supply is missing.
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-