Surge/interference between pump/ph controller

Discussion in 'General Electronics Chat' started by Lee697, Nov 6, 2014.

  1. Lee697

    Thread Starter New Member

    Aug 31, 2014
    26
    0
    I have a power board running various equipment for a tropical fish tank.
    One item is a 240V water pump, another is a pH controller. The pH controller is an electronic device, measures water pH from an electrode in the tank, and switches a solenoid that controls flow of carbon dioxide into the water - more CO2, pH down, stop CO2, pH up etc. The pH controller runs from what seems to be 5V from a USB plug into what I assume is a SMPS.

    When I feed the fish, I unplug the pump, as it blows the food everywhere. When I plug it back in (no switched on powerboard), the pH controller often beeps, shows ERR on its display then seems to reset and go about its usual actions. I'm concerned maybe some sort of surge/interference from the pump starting is causing a problem.
    Any thoughts?
    Lee
     
  2. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,128
    266
    Motors can generate all kinds on nasty interference when powering on or off.

    You could install a switch in-line with the pump, with an RC snubber across the contacts. (this mostly helps kill the OFF transient)
    The pump might also have a high inrush current when turning on, try plugging it into another outlet or circuit in the house and see if that helps.
     
  3. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    Using a LC filter to remove the surge interference when the pump plug in, sometimes the Ground of ph controller will also affected then you need to in series with a toroidal coils through Ground.

    USB 5V → LC filter → 5V(ph controller)
    USB GND → L filter → GND(ph controller)
    L = around 22~50uH toroidal coils as this.
    C = 220 uF
     
  4. Lee697

    Thread Starter New Member

    Aug 31, 2014
    26
    0
    I'll try using a different outlet -would plugging the pH controller into a surge arresting power board be expected to help??


    Thanks Scott - could I trouble you for a quick schematic?? :)
     
  5. ScottWang

    Moderator

    Aug 23, 2012
    4,853
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    Toroidal coils for surge 5V interference_ScottWang.gif
     
    Lee697 likes this.
  6. Lee697

    Thread Starter New Member

    Aug 31, 2014
    26
    0
    Thanks very much Scott....
     
  7. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    The two L are toroidal coil(conductor).
     
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