Help Circuit for 12v "Fox and Hounds" - Automotive

Discussion in 'The Projects Forum' started by gclayjr, Jan 7, 2013.

  1. gclayjr

    Thread Starter New Member

    Jan 7, 2013

    I recently bought an Adjustable (AC) Voltage Detector from my local Hardware store. I would like to use this as a basis for an automotive "Fox and Hounds" circuit to detect broken wres in automotive wiring.

    My idea is to make wave generator that would generate +- 5 volt AC wave (sine?) superimposed on the +12v line vs ground. Is this a good idea? How would you go abot designing such a circuit? I don't think it would be difficult would it?


    George Clay
  2. debe

    Well-Known Member

    Sep 21, 2010
    Cant see it working to well, as automotive wiring is bundled in looms. Have had to trace plenty of automotive circuits for open circuits & shorts. Ohm meter or voltmeter have served me well for may years. Looking for shorts to ground there are a few tricks to make that easy.
  3. wayneh


    Sep 9, 2010
    This would cause everything to see voltages varying from +7 to +17 volts. That sounds bad. I have no idea how, for instance, the main computer might respond to that. Adding a 1V signal might be safe.
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    A pair of Fluke "Bed of Nails" Multimeter Leads is more help than you could imagine!

    They are typically permanently attached to telephone butt sets, but can be bought for around $35. The insulation is self healing, it pushes a few very tiny needles through to the conductor so a reading can be made.

    I've gotten addicted to them. Well, the clips and the wiring manuals.
  5. gclayjr

    Thread Starter New Member

    Jan 7, 2013
    DEBE... I've seen Youtube videos for using "Fox and Hounds" type test equipment in automotive testing and they seem to be very helpful. The fact that wires are looped. or tied into bundles makes this type of a tool all the more useful. Unfortuantely.

    These tools which are common in the Telephone industry can be pretty expensive for example on Amazon:

    is about $150.

    And the manual does say this is used in Automotive:

    I guess I was thinking that it might be nice to be able to use a $40 AC detector like the Hound and create a simple circuit to work like the fox... There might even be a market or such a tool.


    George Clay