My Last coil

[James]

I wound this coil with 660/46 Litz wire, basket weave. I might rewind the coil a little neater, The spec's are 290uh, .42 ohms, former diameter is 20.5 CM. This coil really works, it will detect a gold ring at over the diameter of the coil. I am using the Hammerhead for the test, I might use the little detector later if anyone is curious. Oh the coil has 60 feet of wire wound on the form. Thanks to all the members on the board for their help an support. I think it is time for me to fade into the wood work. Best to all Jim

[waltr]

Looks good.
However, my gold wedding ring is the Easiest target, strongest signal and is detected at the longest distance of any targets I have tried.
This is due to jewelry being not pure gold, 14K is 58% Au, rest copper, and actually has a rather Low conductance so eddy current die slowly. Also a Ring shape produces much strong Eddy current (see the experiments in the book "Inside the metal detector"). Purer gold has a much higher conductance.
The weakest signal of all test targets I have comes from a US Silver dime. High conductance and small, thin, solid.
Check my HH2 thread in the HH II sub-forum.

[Toros]

I wound this coil with 660/46 Litz wire, basket weave. I might rewind the coil a little neater, The spec's are 290uh, .42 ohms, former diameter is 20.5 CM. This coil really works, it will detect a gold ring at over the diameter of the coil. I am using the Hammerhead for the test, I might use the little detector later if anyone is curious. Oh the coil has 60 feet of wire wound on the form. Thanks to all the members on the board for their help an support. I think it is time for me to fade into the wood work. Best to all Jim

You did it with an even number of legs and got coils that did not differ. The next one made an odd number of legs.

[James]

Wrong Picture

I posted the wrong picture, this the final coil winding project for me. This is the Litz 660/45 wire. Back in the wood work My best to all Jim

[6666]

This is the Litz 660/45 wire

whats that type of wire like to wind ? is it flexible

[green]

[ATTACH]42136[/ATTACH] I posted the wrong picture, this the final coil winding project for me. This is the Litz 660/45 wire. Back in the wood work My best to all Jim

Thanks. The coil in reply #1 looked like enamel coated solid. Was going to reply but my eye sight isn't the best and didn't want to question it.


Have you tried monitoring amplifier out of an operating PI with an oscilloscope while you bring one of your other coils near the operating PI coil to measure SRF(self resonant frequency)?

[James]

The wire is very flexible an very easy to wind. Jim

[James]

No I have not, what might I see on the scope? I measure resonant with a scope ,series resistor and scope. I have pretty good luck over the years with that procedure, Best to yo Jim

[James]

I did the air test with the PI-1 small detector and found very good results. The total diameter of the coil is 23.5 CM. I had the detector sounds off on a small 14k silver ring at 25 CM. The dime was at the same distance. Quarters and larger pieces of metal were sounds off at a greater distance. The gold fillings I test with are pretty small, about 1/4 size of a dime, they sounded off at radius or slightly less. I believe large Litz wire makes the magic in the coil. Best to you an your work. Jim

[green]

No I have not, what might I see on the scope? I measure resonant with a scope ,series resistor and scope. I have pretty good luck over the years with that procedure, Best to yo Jim

When the operating PI coil turns off it excites resonance in the test coil(test coil leads open). If the PI amplifier is fast enough you will see the resonance at amplifier out with the scope. The method gives me the highest SRF of any method I've tried.