Homemade 12" Whites Coil

Hello Everyone . We will just take a step at a time and everything will go smoothly . If we can not proceed to the next step then we will do what is needed "to do it right" and then proceed . If somebody told you a concentric search coil is easy and it can be done with just an ohmeter you are being fooled and it will take you a lot more time  . A DD coil is a good first step and a great learning tool , then the next search-coil can be a Concentric coil . Here on Thunting we give suggestions and listen to suggestions to make life easier . Do you ever wonder why some of the other forums never can answer all your questions ? Because they do not have the time , or they do not try hard enough !!! One word here on this forum is "Persistance" . Another thing I have learned over the years is What happens out in the field is not always what is "Engineered on Paper" !!!  Here are things to consider on search coil design/characteristics/Parameters:  DC resistance , Resonance , permeability , Capacitance , Harmonics , Q factor at the resonance frequency  , Noise , phase , eddy currents . Nobody is Wrong here today we are just adding some more theories , facts and statements , opinions and suggestions .
HH...........Regards.........Eugene

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Eugene, thanks for digging that up. Can't wait to read the specs on it. Where is this information coming from? Is it the Jimmy Seria Hot Shot coil or somebody who made a homemade 12" for the Whites. Concentric or double D? Remember that the 12" Whites coils for the DFX/MXT are not compatible with the XLT/QXT.

Doesn't seem right that Whites comes out with 12" coils for their new machines but haven't done so for the 6.59khz line, like the 6000dipro, classics, xlt, qxt, etc. There are NO aftermarket coils bigger than the 9.5" for these machines other than the Jimmy Sierra 12" Hot Shot. I've heard nothing but good things about these coils when used on the XLT/6000, but I bought and tried two new ones on the QXT Pro and both wouldn't work. After about 5 to 10 minutes of working properly they would begin to false badly much like they were getting interference from and outside source. Lowering the sensitivity did not help. After reading about coil designs I'm starting to think that the coil would warm up in the sun and the coils would move as a result. I also tried them in several locations to rule out outside interference but the results were the same....worked fine for about 10 minutes or so and then got unstable.

Yes, I do have a pretty good background in electronics but there are some areas where I don't have much knowledge. What I don't know I'll research and learn to complete the project. The problem is that so far I've found no single article on "This is how to build a concetric coil (or even a double D for that matter) with all the steps and testing described in detail. I can only find minor bits of information here and there scattered all over the web. I know that, regardless of how specific the information is for a certain coil size and machine type, there is still some testing and tuning involved. The problem is nobody covers this information as well...IE: Here's what to check for....Here's what to do if it reads this way...Here's what to do if it reads that way...Etc. This is still a scientific process that utilizes specific steps, testing, and tuning, yet nobody has wrote an article with all the little steps involved. Some of the information I have learned from my own prior experience, some of it has come from what I can dig up, yet there are still a lot of unknowns that nobody has gone over. That's what I'm hoping to find. Again, I know every build will involve a certain amount of testing and adjustment of various things, but that general information should be provided in an article so those lacking certain aspects of knowledge can follow the steps and build a successful coil.



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		Quote:			Posted by nickel_n
	Hi critterhunter I was so surprised reading your post. It’s almost like reading my thoughts under your name even so I haven’t start working on a 6.59 KHz coil. Here is some info about coils that it may help. You are not allowed to view links. Please Register or Login http://deepfriedneon.com/tesla_f_calcspiral.html You are not allowed to view links. Please Register or Login http://www.csgnetwork.com/spiralcoilinduccalc.html You are not allowed to view links. Please Register or Login http://www.coilgun.info/theory/home.htm Thanks again for your post, and please share the info.

Thanks for the links. That fills in a few blanks. Like I said, though, somebody with the knowledge needs to write a start to finish article on building concentric and DD coil designs, including parts, how to test and calibrate the coil, a method of determing a best guess starting gauge and number of turns, etc. For example, anybody can calibrate an adjustable TPS sensor on a car provided they have a list of steps in front of them. What I'm seeing out there for homemade coils is poor at best. What can be found is scattered or buried in messages in some very obscure places on the web. I know a good bit about electronics but coils are a bit out of my league. I need somebody to explain what to test for and why beyond something as simple as resistance or RX voltage. That I grasp. Inductance and related measurements I don't...yet.



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		Quote:			Posted by critterhunter
	Eugene, thanks for digging that up. Can't wait to read the specs on it. Where is this information coming from? Is it the Jimmy Seria Hot Shot coil or somebody who made a homemade 12" for the Whites. Concentric or double D? Remember that the 12" Whites coils for the DFX/MXT are not compatible with the XLT/QXT. Doesn't seem right that Whites comes out with 12" coils for their new machines but haven't done so for the 6.59khz line, like the 6000dipro, classics, xlt, qxt, etc. There are NO aftermarket coils bigger than the 9.5" for these machines other than the Jimmy Sierra 12" Hot Shot. I've heard nothing but good things about these coils when used on the XLT/6000, but I bought and tried two new ones on the QXT Pro and both wouldn't work. After about 5 to 10 minutes of working properly they would begin to false badly much like they were getting interference from and outside source. Lowering the sensitivity did not help. After reading about coil designs I'm starting to think that the coil would warm up in the sun and the coils would move as a result. I also tried them in several locations to rule out outside interference but the results were the same....worked fine for about 10 minutes or so and then got unstabl Yes, I do have a pretty good background in electronics but there are some areas where I don't have much knowledge. What I don't know I'll research and learn to complete the project. The problem is that so far I've found no single article on "This is how to build a concetric coil (or even a double D for that matter) with all the steps and testing described in detail. I can only find minor bits of information here and there scattered all over the web. I know that, regardless of how specific the information is for a certain coil size and machine type, there is still some testing and tuning involved. The problem is nobody covers this information as well...IE: Here's what to check for....Here's what to do if it reads this way...Here's what to do if it reads that way...Etc. This is still a scientific process that utilizes specific steps, testing, and tuning, yet nobody has wrote an article with all the little steps involved. Some of the information I have learned from my own prior experience, some of it has come from what I can dig up, yet there are still a lot of unknowns that nobody has gone over. That's what I'm hoping to find. Again, I know every build will involve a certain amount of testing and adjustment of various things, but that general information should be provided in an article so those lacking certain aspects of knowledge can follow the steps and build a successful coil.

Hello critterhunter . Since 2001 I have been saving everything I can on Metal Detector schematics , circuit boards and search coils , probably a few giga-bytes of files and folders , plus several hundred mega-bytes of "full complete pages" of other Electronic forums . So if I give you some information on something it is probably the most accurate you will find . My main goal on this Forum is to help "Anyone" who wants to build a Metal Detector and or search-coil . I try my hardest to post accurate information . The Reward is when I hear "Thank-You my project works great" !!!!! .............I will post the coil dimensions and winding numbers in just a little bit .
HH........Regards.........Eugene

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		Quote:			Posted by GoldDigger1950
	As silly as this might sound at this moment, perhaps you will write that article some day. Your experiences and experiments will soon make you somewhat of an expert as you find out how these things work. Take good notes as you work and keep your journals together for the future. When you look back on how much you have learned, it will give you what you need to start such a "how to" set of instructions.

Eugene, thanks for the help and look forward to the info!

GoldDigger, that's exactly my plan...to write a little article on concentric and double D coil building from start to finish, and it'll be posted here since you guys seem to be willing to help somebody who doesn't have all the knowledge fill in the blanks. I've written several "How To" threads on the web, mainly dealing with electric RC airplane construction and other tools involved with that. For instance, I recently put together a "How To" with basic steps to convert a $3 Harbor Tool & Freight multimeter to a Wattmeter with the ability to read up to 200 amps. It only involves some simple soldering and calibration to get the unit to handle these high amp draws, as the stock multimeter can only handle and read amp draws up to about 20 amps. Brushless motors for RC craft normaly range in amp draws from about 20 to 40 or so and produce anywhere from 200 to 400 watts of power typicly, being powered by a 3 cell 2250ma lipo cell producing at peak 12.6 volts. Commercial Wattmeters that can read amp draws in that range start at about $50 and go up from there. Obviously, if you can build one with about a half hour of time and at a cost of about $5 it's worth doing. Not only that, but this modified meter is more accurate than many of the commercial units out there. A device like this is useful for trying various prop sizes to insure that you are not drawing too many amps or watts than the motor, battery, and speed control (ESC) can handle. It's a good way to avoid smoking these parts. I'm fairly good at explaining things in basic detail with small steps so that a novice can follow the directions and be walked right through the process of building something. I hope I can contribute in this fashion to coil design and construction with the help of you guys to walk me through the areas I don't understand yet. Thanks again.


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