AC flow detection

Discussion in 'General Electronics Chat' started by papamiketkd, Mar 2, 2014.

  1. papamiketkd

    Thread Starter New Member

    Mar 2, 2014
    2
    0
    I am looking for a simple way to tell if AC current is flowing to a remote motor. I can easily access the outlet neutral or hot line separately. I do not want to invest into buying an expensive clip on amp meter. I don't care what the current level is - just want to know if there is a current flow. Ideally if it could somehow interface with a contact closure switch, I could then connect it with a digital counting device.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,014
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  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Also a simple current transformer or one with logic built in such as honeywell CSDA current sensor series.
    Max.
     
  4. subtech

    Senior Member

    Nov 21, 2006
    123
    4
    Well, if you want cheap and you like to "roll your own":

    Remove the cardboard center from a roll of electrical tape.
    Cut the cardboard such that you can open the tube enough to slip over 1 leg of the motor feed.
    Wrap several turns of small gauge wire (20-24 ga.) around the cardboard form so as to form a simple current transformer.
    Connect one end of the wrapped wire to the anode of a rectifier diode. (1N4001)
    Connect the anode of an L.E.D. to the cathode of the rectifier.
    Connect the cathode end of the L.E.D. to the other end of the wrapped wire.
    Adjust the number of turns of small wire on the cardboard form until the L.E.D. lights
    reliably when the motor is running. Total cost, about $2.00.
     
    Last edited: Mar 2, 2014
  5. papamiketkd

    Thread Starter New Member

    Mar 2, 2014
    2
    0
    Great Ideas - I will look into what you all have suggested!
     
  6. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    I don't believe that works.:confused:
    Some one on here experimented along those lines.
    @60hz a core is needed.
     
  7. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    Find a defunct GFCI and scavenge the sense coil from it. They will drive a LED. Thread one lead powering the motor through the center hole, hook the two wires to a LED, good to go. I used one of those coils and an opto-isolator to drive a counter that monitors my sump pump to keep track of how many times it cycles.
     
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