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Had anyone use other coils like whites,fisher minelab coils with the Hammerhead detector.
I am thinking about building one.
I am thinking about building one.
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Re: Hammerhead coils
For any coil you consider, make sure it is shielded. Some are not. Some coils may have a built-in damping resistor so you just remove the damping resistor from the circuit board. You can check by using a 25 to 30 turns coil of wire pulsed with a square wave and placed near your commercial coil. Look at the ringing in the commercial PI coil on an oscilloscope If it is ringing, it will show a tappering off ringing sinewaves that also indicates the self resonant frequency of that coil. The presence of ringing indicates that there is no internal damping resistor. If it does not show a tapering-off ringing, but a single spike, then it probably has an internal damping resistor. It is better that a coil does not have a damping resistor so you can adjust the damping resistance to match your chosen or homebuilt coil to your PI circuitry
A shield is necessary to isolate the coil from sensing changing ground and picking up noise. Unshielded coils typically detect a hand moved close to the coil at delay times under 15 to 20 uS. Many high power machine, using large coils (3 to 6 ft diamter) use unshielded coils as they are operating at a low frequency and time delays in the mS range. The type of coil and PI machine depends on what you are looking for?
If you are looking for small targets like gold and jewlerly, you probably need to look for a coil that has 300 to 350uh of inductance and anywhere from 1 to 3 or 4 ohms DC resistance. Just note that the Hammerhead is a high-power, medium frequency range type machine and seems to work good with lower resistance coils.
Do a search on the previous posts in this forum under the word "coil". There is a wealth of information about homebuilt coils and commercial coils. Check the new coil parameter database from time to time to see what is added to this web site coil list.
PI mono coils are very easy to build. Get a coil housing from Hays Electronics. This way you can build a coil that will match your desired target responses and the Hammerhead TX circuit design.
bbsailor -
Re: Hammerhead coils
You can use just about any PI coil. The damping resistor will need to be changed to match the coil, a good starting point is to simply use the value that the coil manufacturer used in their PI detector.
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two coils version
Please help me to find how to build two coils and how to be placed for hammerhead II. Did someone made it, give me on this forum picturesComment
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aljacoub
hi all :
i want to build bifilar hammerhead coil ,can anybody help me to make it and if there is video about how can i make it.
regards
aljacoubComment
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