Vehicle loop detector

Discussion in 'The Projects Forum' started by skusku, Aug 9, 2013.

  1. skusku

    Thread Starter Active Member

    Aug 9, 2009
    63
    1
    Hi there

    I would like some help making an inductive loop detector, to detect vehicles.

    Something like this:
    http://www.centsys.co.za/inductive-loop-detectors/flux-sa

    The problem I have, if I use the coil of wire, and put a big metal object over it, I either need it to change frequency or voltage. This would then go into a PIC with A/D conversion. What type of circuit would accomplish the change in voltage so I can compare it.

    Thanks
     
  2. LDC3

    Active Member

    Apr 27, 2013
    920
    160
    If you want to make your own, I found this page, and quite a few others.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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  4. tshuck

    Well-Known Member

    Oct 18, 2012
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    If I remember correctly, the LM331 is a voltage to frequency converter, that can be run in reverse, so it could be as simple as an ADC read.

    You could do this with a timer, no ADC necessary and the result is, by nature, digital...
     
  5. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,690
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    Here's a neat solution. Can the inductor be replaced with a large loop? Don't see why not.
     
    SgtWookie likes this.
  6. #12

    Expert

    Nov 30, 2010
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    You PIC guys are so annoying, using 7 parts to do what would require dozens in an analog design!
     
  7. skusku

    Thread Starter Active Member

    Aug 9, 2009
    63
    1
    As to LDC3 post: will I be able to get different voltages at the pin where the led is at?

    Otherwise the picodetector looks quite nice too. Will have a look at both tomorrow...
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Actually, there should be a couple of changes in that schematic; swap the connections at 6(2) with 5(3), remove the ground from the cathode of the LED, and move the LED to between the 1K2 (1.2k) resistor and pin 7(1). Then at pin 7 (1) you'll see < 0.7v when the LED is on, and ~Vcc - Vf(LED) when the LED is off.

    If you have the means to program a PIC, this would be the way to go.
     
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