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Current sensor problem — Parallax Forums

Current sensor problem

ArchiverArchiver Posts: 46,084
edited 2003-10-05 16:49 in General Discussion
The basement of a house in a high water location is kept dry by a regular water
pump with float switch. The pump is located in a deep well and I am trying to
come up with a convenient monitoring system which should measure how often that
drainage pump starts up every day/every hour/every week??

I need to measure time over days and weeks and month and I need to sense when
the pump switches on by sensing the current going to that pump in its rather
inaccessible location. My signal should be independent of the current drawn,
something like the voltage drop of a diode without the side effect of only
letting half the wave get to the pump.

I am mostly baffled by this current sensor, I have not yet had a good idea.

And of course the inface to show to the world how long the pump ran and when.
Maybe the signal could be temporarily stored in EEprom and send to a desktop on
demand.

To the USB port of an iMAc?? Is that possible with a stamp?

Uwe

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-10-02 03:24
    Take a look at LEM current sensors. They measure the magnetic field
    around the wire of a conductor. Very easy to use. Digikey sells them.

    Jason

    --- In basicstamps@yahoogroups.com, "othello159" <othello159@h...>
    wrote:
    > The basement of a house in a high water location is kept dry by a
    regular water pump with float switch. The pump is located in a deep
    well and I am trying to come up with a convenient monitoring system
    which should measure how often that drainage pump starts up every
    day/every hour/every week??
    >
    > I need to measure time over days and weeks and month and I need to
    sense when the pump switches on by sensing the current going to that
    pump in its rather inaccessible location. My signal should be
    independent of the current drawn, something like the voltage drop of
    a diode without the side effect of only letting half the wave get to
    the pump.
    >
    > I am mostly baffled by this current sensor, I have not yet had a
    good idea.
    >
    > And of course the inface to show to the world how long the pump ran
    and when. Maybe the signal could be temporarily stored in EEprom and
    send to a desktop on demand.
    >
    > To the USB port of an iMAc?? Is that possible with a stamp?
    >
    > Uwe
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-02 14:25
    Yes, a Stamp along with an 8-bin DS1302 RTC
    chip from www.maxim-ic.com, and a 32 Khz
    'crystal'. Also, a 26L640 8Kx8 8-pin eeprom.
    And a 9-volt battery, or a 9-volt DC
    adapter.

    These are VERY easy to interface (see Files
    area under 1302).

    The current sensor has been mentioned in
    other posts.

    You can 'sleep' the stamp, having it wake
    every 2.4 seconds and sample the line, then
    'sleep' again. If the line is active,
    read the 1302 chip to find the time
    (down to the second), log the start, and
    'sleep' again. Keep doing this to log the
    stop time also.

    Store the results to the 8K EEPROM.
    Also monitor the serial port, so you can
    connect your MAC to it and download the
    information.

    All very practical with the Stamp.


    --- In basicstamps@yahoogroups.com, "othello159" <othello159@h...>
    wrote:
    > The basement of a house in a high water location is kept dry by a
    regular water pump with float switch. The pump is located in a deep
    well and I am trying to come up with a convenient monitoring system
    which should measure how often that drainage pump starts up every
    day/every hour/every week??
    >
    > I need to measure time over days and weeks and month and I need to
    sense when the pump switches on by sensing the current going to that
    pump in its rather inaccessible location. My signal should be
    independent of the current drawn, something like the voltage drop of
    a diode without the side effect of only letting half the wave get to
    the pump.
    >
    > I am mostly baffled by this current sensor, I have not yet had a
    good idea.
    >
    > And of course the inface to show to the world how long the pump ran
    and when. Maybe the signal could be temporarily stored in EEprom and
    send to a desktop on demand.
    >
    > To the USB port of an iMAc?? Is that possible with a stamp?
    >
    > Uwe
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-02 14:41
    Assuming it's a 115VAC motor, connect a small light bulb such as a 4w
    nightlight across it. Then detect it using a CDS photocell. Voila! a
    stone-age optoisolator! You may want to put it in a box of some kind so
    that turning on the basement light doesn't trigger it.
    --Stu

    Original Message
    From: "othello159" <othello159@h...>
    To: <basicstamps@yahoogroups.com>
    Sent: Wednesday, October 01, 2003 8:39 PM
    Subject: [noparse][[/noparse]basicstamps] Current sensor problem


    > The basement of a house in a high water location is kept dry by a regular
    water pump with float switch. The pump is located in a deep well and I am
    trying to come up with a convenient monitoring system which should measure
    how often that drainage pump starts up every day/every hour/every week??
    >
    > I need to measure time over days and weeks and month and I need to sense
    when the pump switches on by sensing the current going to that pump in its
    rather inaccessible location. My signal should be independent of the current
    drawn, something like the voltage drop of a diode without the side effect of
    only letting half the wave get to the pump.
    >
    > I am mostly baffled by this current sensor, I have not yet had a good
    idea.
    >
    > And of course the inface to show to the world how long the pump ran and
    when. Maybe the signal could be temporarily stored in EEprom and send to a
    desktop on demand.
    >
    > To the USB port of an iMAc?? Is that possible with a stamp?
    >
    > Uwe
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and
    Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-02 19:20
    I love this solution! Stone-age opto-isolator indeed!

    --- In basicstamps@yahoogroups.com, "Stu Wrenn" <swrenn@z...> wrote:
    > Assuming it's a 115VAC motor, connect a small light bulb such as a
    4w
    > nightlight across it. Then detect it using a CDS photocell. Voila!
    a
    > stone-age optoisolator! You may want to put it in a box of some
    kind so
    > that turning on the basement light doesn't trigger it.
    > --Stu
    >
    >
    Original Message
    > From: "othello159" <othello159@h...>
    > To: <basicstamps@yahoogroups.com>
    > Sent: Wednesday, October 01, 2003 8:39 PM
    > Subject: [noparse][[/noparse]basicstamps] Current sensor problem
    >
    >
    > > The basement of a house in a high water location is kept dry by
    a regular
    > water pump with float switch. The pump is located in a deep well
    and I am
    > trying to come up with a convenient monitoring system which should
    measure
    > how often that drainage pump starts up every day/every hour/every
    week??
    > >
    > > I need to measure time over days and weeks and month and I need
    to sense
    > when the pump switches on by sensing the current going to that pump
    in its
    > rather inaccessible location. My signal should be independent of
    the current
    > drawn, something like the voltage drop of a diode without the side
    effect of
    > only letting half the wave get to the pump.
    > >
    > > I am mostly baffled by this current sensor, I have not yet had a
    good
    > idea.
    > >
    > > And of course the inface to show to the world how long the pump
    ran and
    > when. Maybe the signal could be temporarily stored in EEprom and
    send to a
    > desktop on demand.
    > >
    > > To the USB port of an iMAc?? Is that possible with a stamp?
    > >
    > > Uwe
    > >
    > >
    > > To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@yahoogroups.com
    > > from the same email address that you subscribed. Text in the
    Subject and
    > Body of the message will be ignored.
    > >
    > >
    > > Your use of Yahoo! Groups is subject to
    http://docs.yahoo.com/info/terms/
    > >
    > >
    > >
    > >
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-03 03:06
    Thanks for all these suggestions.
    The location of the pump makes any attaqchments down there quite impractical.
    Also pulling any additional wires would be a drag.

    I like Allens info, even though it will take me a moment to digest it, I am not
    that firm on all this new technology. In particular I have no idea how I would
    interface with my iMac. One does not often see Macs in these applications,
    everything is PC and Allen deals with this problem in one sentence. Maybe there
    is something written up on this topic so I could read up on it.

    Before I can set up Allens fancy version of a sump pump monitor I will go with a
    quick and dirty solution once I lay my hands on a current sensing transformer,
    somewhat along the stone age approach somebody here suggested.
    The recitified signal from the current sensing transformer will be use to power
    a regular wall clock with its 1.5 V battery removed. This will not give me all
    the info I could possibly want, but it will give me the accumulated time the
    pump has been on, which I will jot down daily on a piece of paper.
    I think that will prove to be quite useful and interesting for the beginning.

    Uwe




    --- In basicstamps@yahoogroups.com, "Allan Lane" <allan.lane@h...> wrote:
    > Yes, a Stamp along with an 8-bin DS1302 RTC
    > chip from www.maxim-ic.com, and a 32 Khz
    > 'crystal'. Also, a 26L640 8Kx8 8-pin eeprom.
    > And a 9-volt battery, or a 9-volt DC
    > adapter.
    >
    > These are VERY easy to interface (see Files
    > area under 1302).
    >
    > The current sensor has been mentioned in
    > other posts.
    >
    > You can 'sleep' the stamp, having it wake
    > every 2.4 seconds and sample the line, then
    > 'sleep' again. If the line is active,
    > read the 1302 chip to find the time
    > (down to the second), log the start, and
    > 'sleep' again. Keep doing this to log the
    > stop time also.
    >
    > Store the results to the 8K EEPROM.
    > Also monitor the serial port, so you can
    > connect your MAC to it and download the
    > information.
    >
    > All very practical with the Stamp.
    >
    >
    > --- In basicstamps@yahoogroups.com, "othello159" <othello159@h...>
    > wrote:
    > > The basement of a house in a high water location is kept dry by a
    > regular water pump with float switch. The pump is located in a deep
    > well and I am trying to come up with a convenient monitoring system
    > which should measure how often that drainage pump starts up every
    > day/every hour/every week??
    > >
    > > I need to measure time over days and weeks and month and I need to
    > sense when the pump switches on by sensing the current going to that
    > pump in its rather inaccessible location. My signal should be
    > independent of the current drawn, something like the voltage drop of
    > a diode without the side effect of only letting half the wave get to
    > the pump.
    > >
    > > I am mostly baffled by this current sensor, I have not yet had a
    > good idea.
    > >
    > > And of course the inface to show to the world how long the pump ran
    > and when. Maybe the signal could be temporarily stored in EEprom and
    > send to a desktop on demand.
    > >
    > > To the USB port of an iMAc?? Is that possible with a stamp?
    > >
    > > Uwe
  • ArchiverArchiver Posts: 46,084
    edited 2003-10-05 13:10
    I'm doing the same thing with my sump pump, using a CR Magnetics current
    indicator model CR2550. Very cheap (about $10US), and it turns on at .75A
    which should cover all but the wimpiest of pumps. Use a phototransistor and
    a piece of shrink tubing to make a post-stone age, pre-Renaissance
    optoisolator to get an output for the Stamp. This method does require having
    access to the AC wiring, but it can be anywhere along the circuit (provided
    there are no other loads downstream that might give false readings),
    preferrably right at the receptacle the pump plugs into. Here's the link:


    http://www.crmagnetics.com/newprod/ProductView.asp?ProdName=CR2550

    Good Luck!
    Tom

    <Date: Fri, 03 Oct 2003 02:06:59 -0000
    < From: "othello159" <othello159@h...>
    <Subject: Re: Current sensor problem
    <
    <Thanks for all these suggestions.
    <The location of the pump makes any attaqchments down there quite
    impractical.
    <Also pulling any additional wires would be a drag.
    <
    <I like Allens info, even though it will take me a moment to digest it, I am
    not
    <that firm on all this new technology. In particular I have no idea how I
    would
    <interface with my iMac. One does not often see Macs in these applications,
    <everything is PC and Allen deals with this problem in one sentence. Maybe
    there
    <is something written up on this topic so I could read up on it.
    <
    <Before I can set up Allens fancy version of a sump pump monitor I will go
    with a
    <quick and dirty solution once I lay my hands on a current sensing
    transformer,
    <somewhat along the stone age approach somebody here suggested.
    <The recitified signal from the current sensing transformer will be use to
    power
    <a regular wall clock with its 1.5 V battery removed. This will not give me
    all
    <the info I could possibly want, but it will give me the accumulated time
    the
    <pump has been on, which I will jot down daily on a piece of paper.
    <I think that will prove to be quite useful and interesting for the
    beginning.
    <
    <Uwe

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  • ArchiverArchiver Posts: 46,084
    edited 2003-10-05 16:49
    --- In basicstamps@yahoogroups.com, "Tom S" <whyrnutz@h...> wrote:
    > I'm doing the same thing with my sump pump, using a CR Magnetics
    current
    > indicator model CR2550. Very cheap (about $10US), and it turns on
    at .75A
    > which should cover all but the wimpiest of pumps. Use a
    phototransistor and
    > a piece of shrink tubing to make a post-stone age, pre-Renaissance
    > optoisolator to get an output for the Stamp. This method does
    require having
    > access to the AC wiring, but it can be anywhere along the circuit
    (provided
    > there are no other loads downstream that might give false
    readings),
    > preferrably right at the receptacle the pump plugs into. Here's the
    link:
    >
    >
    > http://www.crmagnetics.com/newprod/ProductView.asp?ProdName=CR2550
    >
    > Good Luck!
    > Tom


    Ah, and the output is current based so you can make your own
    extention cord and slip this over the hot wire and then use it for
    most any appliance.

    also, for those low-low-low power things, you can loop the wire in
    the CT, each time thry adds a full scale reading. Remember, this is
    the basis of a transformer.

    Dave
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