Liquid Level Sensor

Discussion in 'The Projects Forum' started by scollinguk, Jan 31, 2011.

  1. scollinguk

    Thread Starter Member

    Oct 9, 2010
    34
    0
    Hi All,

    I am trying to make a auto topup system for a fish tank.

    I have a perilstaltic pump which I have been using with a float switch for this but have now got a liquid level sensor but cant get it to work.

    The basic setup is a 12v DC 300ma adaptor, the pump which is powered by what is essentially a 12v drill motor and the liquid level sensor which is rs components part number 285-778, link below to instruction leaflet.

    http://docs-europe.electrocomponents.com/webdocs/001a/0900766b8001afe5.pdf

    I currently have the negative from the adaptor connected to the negative on the pump and the blue wire on the sensor. The positive from the pump then goes to the black wire on the sensor. The positive from the adaptor goes to the brown wire on the sensor.

    Can someone tell me how this should be connected please?

    Cheers!
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Have you tried running the motor, powered directly off the adapter, without the sensor/switch? 300mA sounds a bit small to power a 12V drill motor. And, the sensor switch is only rated at 200mA.

    Ken
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The information sheet says nothing about the current output rating of the switch, but I suspect it's pretty low; and if you try to drive a motor with it directly, you will likely burn up the unit very quickly if not instantly.

    The brown wire goes to +12v.
    The black wire supplies current to the load, the other side of the load gets connected to ground (0v).
    The blue wire goes to the 12v return (ground).

    So, you seem to have it connected as according to the sheet.
    But without any more information about the motor current rating and the switch rating, all bets are off.
     
  4. scollinguk

    Thread Starter Member

    Oct 9, 2010
    34
    0
    Hi Ken,

    Yes the motor works from the adaptor if its directly connected to it, I have literally just tested it to make sure the motor hadnt stopped working for any reason.

    Cheers
     
  5. scollinguk

    Thread Starter Member

    Oct 9, 2010
    34
    0
    Hi SgtWookie,

    The sensor has a switching rating of 200ma.

    The motor needs 2.6w so 216ma at 12v but the adaptor is putting out 18v when I measure it with my multimeter.

    The adaptor is one of those variable voltage ones with a slider on the plug to alter the output voltage. I have run the motor at the 3v setting previously for a different application (for about 3 months).

    I have also just noticed that the LED on the sensor isnt coming on even if I just connect the wires from the adaptor to the blue and brown wires of the sensor.

    Do you think the sensor is buggered?
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Yes, I think the switch is a binner.
     
Loading...