Buried wire detector

[Kiwi Bruv]

Hi have basic electronics knowledge.

I am building a robot that I want to stay confined in an area outside on the lawn. I want to bury a wire in the ground and use a detector on the robot to keep it within the boundary.

I know induction is probably how the thing will work but I have no knowledge.

Power consumption needs to be low on the detector and supply will be 12V. Size needs to be small.

I don't know if it'll be a passive system ie no signal in the buried wire or not. the sensor output could be analogue or digital, I can handle either.

Can anyone help me with some circuits? I can build it and test it, just can't design the detector.

 

[audioguru2]

Hi Kiwi,
Welcome to our forum.
My cable-TV guy had a very expensive and high-tech buried cable detector that showed the cable length and depth. I called him when my neighbour got a new driveway and my cable got broken.
He dug up my whole yard finding telephone cables and old car parts.

Pet stores sell gadgets that give a mild shock to a dog that strays beyond a buried cable. Its detector is small and low-powered. Try a Google search for the circuit for one. ;D

 

[Kiwi Bruv]

Thankyou.

I've tried the google search but can't find any circuit details just retail invisible fences.

Will keep trying though.

 

[abdul jawad]

Hi Kiwi,
Welcome to our forum.
My cable-TV guy had a very expensive and high-tech buried cable detector that showed the cable length and depth. I called him when my neighbour got a new driveway and my cable got broken.
He dug up my whole yard finding telephone cables and old car parts.

Pet stores sell gadgets that give a mild shock to a dog that strays beyond a buried cable. Its detector is small and low-powered. Try a Google search for the circuit for one. ;D

 

[Yevgenip]

What's with the quote?

 

[Yevgenip]

Perhaps use a metal detector mechanism.

 

[Guest]

I had seen a simple circuit. It used a simple coil of copper wire of approx. 1mh . It was given to the + - inputs of IC 741. The gain was set to a required level. The output was given to a earphone.

Whenever the coil was moved over a wire(carring current),the earphone picked it up.

I have not tried it.

Now if you can get your robat to sense the intensity of the sound it move over it.

 

[Kiwi Bruv]

Thanks Siddarth,

I picked up the same circuit today. I'll start experimenting after xmas.

 

[Guest]

Tell how did it work out.

 

[surajbarkale]

You need to measure two variables here -
1. Strength of signal
2. Direction of Signal
You can feed a unique high frequency signal to the wire at one end so that the wire acts as antenna. And use a sensitive detector to pick up the signal. You shall need two antennas to check the direction.

Same can be achieved by checking the magnetic field generated by wire using hall effect sensors. But I think you shall need insane amount of current through wire for this kind of tracking. ;D

 

[ante1]

Hi Kiwi,

You need an invisible

 

[EnigmaOne]

hmmmmm....definitely good potential for a robotic lawn mower.

I'd use a buried loop, driven with a 1KHz to 5KHz signal as an invisible border. You could use low-voltage, direct-bury sprinkler control cable, and wire the multiple conductors to obtain a multi-turn coil very easily.

Use 3 inductive pickups, at 120 degree intervals on the bottom edge of a circular robotic chassis.

Amplify the signal from each inductive pickup and bandpass-filter the amplifier output to obtain only the frequency that you're interested in.

Feed the filtered output to a comparator and use the three comparator outputs as border proximity inputs to your microcontroller.

From that point, it's merely a matter of the same type of programming that you would do for a simple obstacle avoidance routine.

 

[ante1]

Well, summed up this is high level consulting worth getting paid for (almost)! ;D ;D ;D

 

[Kiwi Bruv]

Many thanks everyone.