Litz Wire Coil

[James]

I have one more question for the Guru's, how critical is the value of the damping resistor to over all coil performance? I am using a 390 ohm and it seems to work, but I notice that damping resistor are not talked about on the coil part of the board. Thank you all for your help and suggestions. I am always open to learn new information. Best to all Jim

[Qiaozhi]

I have one more question for the Guru's, how critical is the value of the damping resistor to over all coil performance? I am using a 390 ohm and it seems to work, but I notice that damping resistor are not talked about on the coil part of the board. Thank you all for your help and suggestions. I am always open to learn new information. Best to all Jim

Look at the output of the pre-amp with an oscilloscope, and use a damping resistor adjustment tool to achieve critical damping. Then measure the resistance and replace the tool with a fixed damping resistor.

http://www.geotech1.com/forums/showt...785#post227785
https://www.amazon.com/Inside-Metal-...DDMSEQ5SG7TWCJ

[James]

Thank you for damping resistor information. Best to all Jim

[dbanner]

here are some variations on basket weave coil and instructions on how to make.

[6666]

here are some variations on basket weave coil and instructions on how to make.

Its interesting re reading that PDF, it states the capacitance for that type of wind is about 80 pF, which is pretty low and should give a fairly fast coil,
by comparison when we look at the estimated / measured capacitance of SIMPLE flat basket weave / flat spiral weave coils they appear to be even lower.
Dont know why the second image turned sideways.

[James]

I would like to thank all the board members for so much information, about the Litz wire wound coils. I find the coils to be the most interesting part of a P.I. type detector. I think that is where the magic is located an why some detectors work spot on an others well not so good. I use two different P.I. detector boards, the results with either detector is same when testing coils. I did watch the you tube video about repairing the Australian detector coil, for the life of me I can not see where the carbon paper is of any benefit. Thanks again for answering my questions I have had. Best to all Jim

[dbanner]

6666, I noticed the same thing as well, That is why I abandoned making basket weave a long time ago, in favor of flat spiral. The last spiral i made gave me the best results ever. It turned my surf pi into a monster. I get app. 10 inches depth on most coins,12 inches on gold ring.These are actual tests in dry beach sand over here. I'm looking for a simple jig that would make winding flat coil much easier.

[dbanner]

And this is best coil calculator i have ever used for bundle coils. It is very accurate when compared to actual measured coil.

[6666]

6666, I noticed the same thing as well, That is why I abandoned making basket weave a long time ago, in favor of flat spiral. The last spiral i made gave me the best results ever. It turned my surf pi into a monster. I get app. 10 inches depth on most coins,12 inches on gold ring.These are actual tests in dry beach sand over here. I'm looking for a simple jig that would make winding flat coil much easier.

thats easy, a spacer and 2 disks, one disk with slots to apply glue.

[James]

Wow now I am confused, what I get out of your post is a flat spiral wound coil has less capacitance than a basket weave coil? I assume that the coils were not wound with Litz wire ? If I am wrong please feel free to correct me. I think a spiral coil wound be much easier to wind. I sure would appreciate any information? Best to all Jim

[dbanner]

All thing being equal, generally speaking, it seems so. take a look at these coils which were measured.

[dbanner]

As you can observe, at least from this comparison, the fastest coil is the flat radial.

[James]

Thank you for sharing the information about the spiral wound coil. I now curious about building a coil, when I get a few extra minutes. I am going to measure the capacitance of my home made coils. I think I will have a better hands on feeling for making faster coils. Again I would like to thank the members of the board for sharing the information. Best to all Jim

[James]

I have a question, about construction of a spiral coil, using Litz wire. I for the life of me can not understand how to wind the coil without it falling apart. There must be some form of a special device used in winding the coil, because the Litz is so flimsy. Thank you all for any advice you can share with me. Best to all Jim

[ionut_mtb]

I have a question, about construction of a spiral coil, using Litz wire. I for the life of me can not understand how to wind the coil without it falling apart. There must be some form of a special device used in winding the coil, because the Litz is so flimsy. Thank you all for any advice you can share with me. Best to all Jim

Double sided tape. I just made it yesterday in about 10minutes