Home Made Coils for Sand Shark?

[Deese]

Has anyone on here ever made a larger coil for a sand shark? Would there be any reason why you could not make your own larger coils? It's just a 2 wire loop if I am not mistaken. I would like to make something like a 3x3 or 4x4 loop to detect large objects up to 10' or so.

 

[Deese]

Not alot of love for sand sharks in the world I guess, I don't really understand that. I think my sand shark is the best detector I have ever owned for the purpose it is intended for. I have had a few top end vlf machines for land and have not been satisfied with any of them yet.I bought a new gold bug se which should be here today and I am hoping it will be better than what I have had. What other PI machines are there that you think will out do the Tesoro? I'm trying to learn something here,tell me about your favorite PI machine.

 

[Reg]

Hi Deese,

I have never built a coil for the Sand Shark so I can't tell you just what you need to do.

Now, if you have an inductance meter or know someone who does, you can check the inductance of the coil that comes on the Sand Shark and simply match it. I suspect the resistance isn't that critical but the inductance probably is within a reasonable limit.

Typical coil inductances are generally between 200 uh and 300 uh so I expect the Sand Shark to fall in that range. There are a few earlier units that had 1 mh inductance coils also but if my memory is correct, this unit has a spiral coil made by etching the winding on pc board material. As such, I suspect the inductance is one of the lower values.

Many years ago, I looked inside one of these units and found the design to appear to not be that critical, meaning I suspect a fairly wide range of coils might work within the inductances mentioned.

Sorry I can't provide more accurate info about your unit.

Reg

 

[Deese]

Hi Deese,

I have never built a coil for the Sand Shark so I can't tell you just what you need to do.

Now, if you have an inductance meter or know someone who does, you can check the inductance of the coil that comes on the Sand Shark and simply match it. I suspect the resistance isn't that critical but the inductance probably is within a reasonable limit.

Typical coil inductances are generally between 200 uh and 300 uh so I expect the Sand Shark to fall in that range. There are a few earlier units that had 1 mh inductance coils also but if my memory is correct, this unit has a spiral coil made by etching the winding on pc board material. As such, I suspect the inductance is one of the lower values.

Many years ago, I looked inside one of these units and found the design to appear to not be that critical, meaning I suspect a fairly wide range of coils might work within the inductances mentioned.

Sorry I can't provide more accurate info about your unit.

Reg

No need to be sorry Reg,I appreciate your input. I have sent Tesoro an email about the coil connector,and I stumbled on Hay's electronics from a pdf I was reading about the Hammerhead PI project on Geotech.Hay's has all the coil shells I ever wanted,so when I can source the connector I think I will build a few coils for my sand shark.I intend to pick up an inductance meter and a scope,I have read that the coils are around 350uh for the sand shark as well.There is one thing I am not sure of and that is if the sand sharks printed spiral coil has a faraday sheild or not? Maybe I can scare up a shematic of it,would the sheild be connected to one of the coil leads? Because the connector is rubber so it doesnt connect through the threaded nut.

 

[Reg]

Hi Deese,

I am sure the Sand Shark coil would need a shield. That is something simple to do by using something as basic as Scotch 24 shielding tape. This is a metal fabric type tubing that is fine enough to almost be called a metallic netting. Anyway, I cut mine in half length wise so I end up with two pieces long enough to shield the windings of two identical coils. One can spiral the material around the winding being careful to leave a gap on the circumference so the shielding doesn't act like a shorted turn.

With practice one will find it isn't that difficult to build a coil for detectors such as the Sand Shark.

Reg