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DIY current switch? — Parallax Forums

DIY current switch?

yonubearyonubear Posts: 4
edited 2012-03-27 22:44 in Accessories
first let me say I like the forums I have read some interesting stuff and am glad to be here.

now for my question could anyone help me out I need to build a current switching switch that I can place around a AC hotwire that will simply open and close a connection when the hot wires is powered. I hope this makes sense.

Thanks,
Yonubear

Comments

  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2012-03-24 07:56
    SparkFun sells one here: http://www.sparkfun.com/products/11005
  • yonubearyonubear Posts: 4
    edited 2012-03-24 10:42
    thanks for the link however this generates current which I am not sure if this will work for what I have in mind what I am trying to do is trigger a alarm zone when a appliance is on using the wire leads from the old door switch

    Thanks,
    yonubear
  • kwinnkwinn Posts: 8,697
    edited 2012-03-24 15:34
    Ron's link is to the proper device to do what you want to do safely. Unfortunately you may need to add some circuitry since the small output current of the device may not be enough to activate a relay. I am assuming when you say "alarm zone" you want to close a contact that is connected to an alarm system.
  • yonubearyonubear Posts: 4
    edited 2012-03-24 15:48
    ok thanks and yes I am talking about a connection on an alarm system like a door jamb switch would connect to

    thanks,
    yonubear
  • yonubearyonubear Posts: 4
    edited 2012-03-24 18:31
    hey stupid question I assume I will need a transister in order to get it to close the contact however I was wondering as I will need about 9 of the sensors and every dollar counts these days

    will this work since it is only rated at 5amp as the circuits they are going on handle up to 15 http://www.ebay.com/itm/0-5A-Input-Current-Transformer-Sensor-TA12L-200-2000-1-/300669855404?pt=LH_DefaultDomain_0&hash=item460151e6ac

    Thanks,
    yonubear
  • kwinnkwinn Posts: 8,697
    edited 2012-03-26 18:19
    yonubear wrote: »
    hey stupid question I assume I will need a transister in order to get it to close the contact however I was wondering as I will need about 9 of the sensors and every dollar counts these days

    will this work since it is only rated at 5amp as the circuits they are going on handle up to 15 http://www.ebay.com/itm/0-5A-Input-Current-Transformer-Sensor-TA12L-200-2000-1-/300669855404?pt=LH_DefaultDomain_0&hash=item460151e6ac

    Thanks,
    yonubear

    That should probably work as an on/off indicator. It may even put out enough current to drive a very low power relay. Need the data sheet to be sure though.
  • groggorygroggory Posts: 205
    edited 2012-03-27 10:36
    That's just an inductor with the current carrying wire going through the middle right?
  • kwinnkwinn Posts: 8,697
    edited 2012-03-27 22:44
    groggory wrote: »
    That's just an inductor with the current carrying wire going through the middle right?

    Essentially correct but it acts as a current transformer. Typically they have something like 2000 turns of wire on the inductor. In a perfect universe that would mean that a 2 amp current on the wire in the middle would produce 1/2000 amps or 1 mA on the inductor wire. The output voltage would depend on the load. If you connected a 1K resistor as a load the output voltage would be 1V.
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