Possible coatings for Toroidal Forms and Coils????

[Randy Seden]

July 19th,1999


Rick,


I haven't been able to find the magazine that had the ad! I'm still going thru the stacks of ICMJ I was givin (1959-1999,alot of reading!!). If I come across it I'll let you know. Meanwhile I'm putting my efforts into designing and building an Induced Polarization set, as it's the latest and most accurate method used by the Geophysicists for detection of various kinds of ore using the fall time of the return pulse (Gold is around 15 miliseconds or so). Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain


will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


Randy Seden


Simi Valley, Ca.

[Randy Seden]

Re: VLF Detector Depth Enhancement

July 19th,1999


Rick,


I haven't been able to find the magazine that had the ad! I'm still going thru the stacks of ICMJ I was givin (1959-1999,alot of reading!!). If I come across it I'll let you know. Meanwhile I'm putting my efforts into designing and building an Induced Polarization set, as it's the latest and most accurate method used by the Geophysicists for detection of various kinds of ore using the fall time of the return pulse (Gold is around 15 miliseconds or so). Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain


will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


Randy Seden


Simi Valley, Ca.

[Randy Seden]

Re: VLF Detector Depth Enhancement

July 19th,1999


Rick,


I haven't been able to find the magazine that had the ad! I'm still going thru the stacks of ICMJ I was givin (1959-1999,alot of reading!!). If I come across it I'll let you know. Meanwhile I'm putting my efforts into designing and building an Induced Polarization set, as it's the latest and most accurate method used by the Geophysicists for detection of various kinds of ore using the fall time of the return pulse (Gold is around 15 miliseconds or so). Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain


will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


Randy Seden


Simi Valley, Ca.

[Randy Seden]

Re: VLF Detector Depth Enhancement

July 19th,1999


Rick,


I haven't been able to find the magazine that had the ad! I'm still going thru the stacks of ICMJ I was givin (1959-1999,alot of reading!!). If I come across it I'll let you know. Meanwhile I'm putting my efforts into designing and building an Induced Polarization set, as it's the latest and most accurate method used by the Geophysicists for detection of various kinds of ore using the fall time of the return pulse (Gold is around 15 miliseconds or so). Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain


will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


Randy Seden


Simi Valley, Ca.

[Carl]

Re: VLF Detector Depth Enhancement

Randy, I've did some experiments with VLF injection a while back. The detector makes really weird sounds, but the short of it is no depth enhancement. Probably hurt depth as it might have shifted the detection threshold slightly.


Would like to know more about IP if you have info.


- Carl

[Carl]

Re: VLF Detector Depth Enhancement

Randy, I've did some experiments with VLF injection a while back. The detector makes really weird sounds, but the short of it is no depth enhancement. Probably hurt depth as it might have shifted the detection threshold slightly.


Would like to know more about IP if you have info.


- Carl

[Carl]

Re: VLF Detector Depth Enhancement

Randy, I've did some experiments with VLF injection a while back. The detector makes really weird sounds, but the short of it is no depth enhancement. Probably hurt depth as it might have shifted the detection threshold slightly.


Would like to know more about IP if you have info.


- Carl

[rick]

Re: VLF Detector Depth Enhancement

Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain[/i]


>will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


???---have not read any on this---but do know that


if you dampen the soil to increase conductivity,


(dry soil not too conductive and 1000 v to get currant) and inject


60 hz at some 100-200 volts---rods some 10 feet


apart you can get earth worms to come up in a


very large number-----at least in ohio---


rick

[rick]

Re: VLF Detector Depth Enhancement

Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain[/i]


>will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


???---have not read any on this---but do know that


if you dampen the soil to increase conductivity,


(dry soil not too conductive and 1000 v to get currant) and inject


60 hz at some 100-200 volts---rods some 10 feet


apart you can get earth worms to come up in a


very large number-----at least in ohio---


rick

[rick]

Re: VLF Detector Depth Enhancement

Yep, with a 555 and a 100 watt 12volt car stereo amp., you could pump some serious current into the earth. For the receiver, a simple pickup loop into a opamp chain[/i]


>will do nicely. It's worth putting rods into the earth, knowing your efforts will be rewarded!


???---have not read any on this---but do know that


if you dampen the soil to increase conductivity,


(dry soil not too conductive and 1000 v to get currant) and inject


60 hz at some 100-200 volts---rods some 10 feet


apart you can get earth worms to come up in a


very large number-----at least in ohio---


rick

[Dale Seppa]

Possible coatings for Toroidal Forms and Coils????

[email protected]


103 North Sixth Avenue


Virginia, MN 55792 USACOIL INFORMATION - Generally speaking


refers to Tesla Coils


which is obviously a different application. Nevertheless, in my


opinion anything that is good


for a Tesla Coil should be MORE THAN good enough for our proposed


application. Obviously


much of the stuff included will be superfluous so I would appreciate


any comments from


those more knowledgeable than me. Most of this excerpted from


various Tesla Coil


sites. There is much duplication on these sites so it is very hard


to assign


credit or responsibility for many statements.


The coil form should be a low loss material (we are talking about


radio frequency


losses in the 50 - 1000 kHz range) like polyethylene, polystyrene,


or polypro-


pylene, polycarbonate (Lexan), acrylic (Plexiglass), or even ABS or


PVC.


The coil form must be free of major surface imperfections. I wet


sand my coil


forms with #150 wet/dry sandpaper (or emery cloth) and water to


remove markings,


oxidation, scratches and cuts. After wet sanding, the coil form must


be dried


thoroughly. If PVC plastic is used the coil form should be dried in


a drying box,


gently baked under a heat lamp, or even placed in a very low


temperature oven for


a few days. PVC coil forms must then be sealed to negate the high RF


loss factors


that are inherent to this plastic. Sealing also prevents PVC


plastic from reab-


sorbing moisture. Using a sealer such as petroleum based


polyurethane varnish,


two-part clear epoxy paint, or some acrylic spray sealers is


important. Avoid wa-


ter based and milky "emulsion" type sealers.


If drips and sags do occur, then can be "grated" off with a body


putty grater, or


carefully trimmed away with a knife while the sealant is still


pliable.


The coil should be close wound with a good quality magnet wire. I


use double Form-


var enamel coated magnet wire purchased surplus, but newer


insulations such as


Polyimide coatings are even better. Magnet wire gives the maximum


inductance per


unit volume of coil form.


Q. How would someone go about drying a PVC or similarly hygroscopic


material be-


fore it was to be sealed? In the oven? What temperature? Is the


interior of the


form sealed as well?


A. Before I get to the drying stage, I go ahead and wet sand the


coil form with


abrasive paper or emery cloth. I use a #150 grade of abrasive and


sand with water


until all printing, oxidation, and major dings (cuts and scratches)


are removed.


One of the best ways to dry this plastic is to get a large cardboard


box. Cut a


few small vent holes in the top and bottom of the box. Thread some


string or


light cord through the top of the box to form a sling to hold the


coil form. You


will need two or three loops of cord inside the box to securely


suspend the coil


form near the top vent holes. Place a light bulb on a heat resistant


insulator in-


side the box directly below the coil form. Depending on the ambient


temperature,


the size of the box, and the number of vent holes, the wattage (or


number) of


bulbs may be varied. The heat from the bulb(s) will produce a warm


air convection


inside of the box that will effectively dry the coil form over a


period of no


more than three days. The temperature does not need to be very high,


temperatures


between 120 - 150 degrees F are just fine.


Once removed from the drying box, the outside of the coil form


should be sealed


immediately, then wound with wire. Once the coil form is wound, the


ends of the


coil form are capped with plastic disks glued down with epoxy to


form a hermetic


seal. However, if the coil form is removed from the drying box and


winding is de-


layed for some reason, one coat of sealer should be applied to the


inside of the


coil form to prevent moisture from reabsorbing. If the winding


proceeds at an or-


derly pace without delays, then the end caps will prevent air


exchanges which re-


moves the need to seal the inside surface of the coil form.


Q. Besides polyurethane what is a good sealer for a secondary coil


form and where


do I get this sealer?


A. The coating that I used is called Super Gloss Build 50 by Behr.


I got it at the hardware store. (Hugh M. Woods, aka Payless


Cashways) It is in two


paint cans, shrink wrapped together. The can wrappers are orange.


The stuff is


stocked in the varnish section, right next to the polyurethane. The


potential


problems are bubbles, which didn't seem to make much of a


difference for me, and


annular bulges. The bulges appear if you don't get the coating on


evenly and the


form is turning. I would not recommend using Build 50 as a coating


unless you feel


confident in your abilities to apply it smoothly and evenly. I


ended up with some


bulging, but it doesn't detract from the over all appearance. It


would however


cause problems if one used it to seal a PVC pipe under the winding.


This would


make the windings irregular and probably cause the top coat to be


very uneven as


the stuff bulges and climb towards the high spots as the form turns.


Neverthe-


less, I still recommend Build 50 since it goes on in one coat and


is quite tough


and hard. Chip Atkinson


Q. And what about using a Silicon RTV type cement to attach the


ends. This stuff


is definitely non-flamable and is hard to screw-up with.


A. Good Question! Sounds great does it not..? But... These adhesives


leave a re-


sidual acetic acid vapor which is trapped in the coil form. The


acetic acid vapor


is highly conductive and ionizes readily. DO NOT USE THESE PRODUCTS


in this par-


ticular application.


Importing text written by Steve Crawshaw:


I've just intercepted RQ's request for info on secondary coatings,


and I thought


I'd throw my info in here. In UK there is a component distributor


called RS Com-


ponents who supply all sorts of electronics gear. They have a number


of products


for HV insulation. I have got hold of a tin of the following Anti


Corona Lacquer


569-290 $2.86 400ml Aerosol. This has a dielectric strength of


48Kv/mm with a


working temperature of up to 150 degrees C.


BTW, the reason I have recommended that solvent based adhesives NOT


be used when


capping the coil form is because the explosive vapors are trapped


inside of the


coil. If points #1-3 are followed then point #4 should not be too


critical, but if


an internal failure of the secondary coil does occur, you can count


on any


trapped vapors igniting and an explosion will result. This is not


just an idle


warning either. I have had it happen and it was nothing but dumb


luck that a seri-


ous accident did not result.


Q. Quoting Ed H: On the subject of coatings:> Richard Hull (or


TCBOR) mentions in


the guide to the Colorado Springs notes that he/they don't use


secondary coatings


anymore - or at least they were using only a single thin coat. He


says they avoid


breakdown from the coil by proper terminal placement. Any comments


on Hull's


method?


A. Yes, Hull's method works just fine. Many times I have test fired


a coil with no


coating whatsoever. While coating is not an absolute necessity, it


is worthwhile


for several reasons. Coatings prevent the winding from loosening and


slipping off


the coil form. Coatings decrease the chances of a coil suffering


permanent dam-


age as a result of over-coupling and "splitting". Coatings provide


physical pro-


tection to the winding and help prevent serious damage to a coil


that may result


from bumps, dings, cuts, falls, etc. During experimentation a


coiler may choose


to deliberately over-drive the coil, the coil may be overdriven


accidently, or


the coil may be fired in unusual configurations where the electrical


stress may be


high (Tesla Magnifier and bi-polar configurations for example). The


coating does


reduce corona losses and reduces the incidents of electrical


breakdowns. A well


applied coating looks good, and can be maintained. I guess the


argument here is


that if you are winding a coil to become part of a permanent system


where changes


are rarely or infrequently made (like a museum or display coil) one


or two light


coats of sealant, or just enough to stick the windings down, would


be fine. Once


tuned and adjusted with a proper toroid the coil will function well,


and without


excessive corona losses. But on the other hand if you are like me;


a person who


frequently removes/replaces/stores coils, changes primary


configurations, gaps,


caps, dischargers, fires an occasional Magnifier or bipolar system,


etc.. The ben-


efits of a good heavy coating are clear, if for no other reason


than protecting


the winding from accidental physical abuse.


I have found that the benefits of a heavy coating on the secondary


far outweigh


the advantages of a light or nonexistent coating. Also, there are a


lot of begin-


ners out there. Beginners especially need the physical and


electrical ruggedness


that a heavy coating provides.


Text file for COILBLD2.GIF, graphical instructions for construction


of high per-


formance 1/4 wave Tesla resonators.


Once the coil is wound, it is sealed to prevent corona leakage and


to help protect


against electrical breakdown between turns. Sealing also prevents


the windings


from loosening up on the coil form. I use the same sealers mentioned


earlier,


those being petroleum based polyurethane, two-part clear epoxy


paint, or water


free acrylic. Coats of sealer are applied with a brush or spray


until there are


no ridges and valleys in the wire. In other words the coats must


build up until


the wire is completely imbedded in sealer. A fan and radiant heat


source may be


used as required to speed the cure rate of the sealer. Rotating the


coil on the


winding spindle will aid in obtaining a smooth coating that is free


of runs and


drips.


Polymide - This insulation has the best high temperature


properties of


all wire enamels developed to date. Its burnout,


heat shock, and thermoplastic flow resistance far excels


that of all


other enamels.


From Chip - Build Super Gloss. Purpose: Interior decoupage & super


laminate.


Made by Behr Process Corp. Santa Ana 92704. The stuff's for


laminating things


such as bar tops, table tops, etc. It's basically two part epoxy.


It smells like


epoxy and cures like it. It smells like epoxy and cures like it


too. It's clear


as water. There is no solvent base, but you can clean it up with


acetone. There


is a hazard label which says causes severe eye and skin burns.


NEW. I have coated two secondary coils with Polyurethane coatings


in the last 20


months with good result. I should really qualify that remark "good


results". My


goal was to provide a means of locking the wire onto the form, make


the entire as-


sembly moisture proof and also create a high gloss finish simply to


improve the


appearance. I never spend any time check on any improvement in the


overall coil


dielectric properties.


I would strongly recommend NOT using WATER-BASED polyurethanes, this


stuff is crap


IMHO. Go with the clear gloss oil-based stuff. I prefer Behr for


its super fast


drying times, and I have the new low VOC Minwax stuff - it takes WAY


too long to


dry. Also I am curious if anyone has used Behr's Build 50; this is


the thick ep-


oxy coating that is used to make those tacky bar tops with the old


coins in


them... It is supposed to be as thick as 50 coats of urethane, but


it's also de-


signed to be applied to any flat horizontal surfaces, to prevent


running and pool-


ing, so I have my doubts about getting it to work on a cylindrical


coil. ADAM.


NEW. I'm puzzled about the cracking comment too. It probably


depends on the par-


ticular brand of polyurethane, but I've had excellent results from


the good old


"Behr Super Build 50" product. This last February I ran a test of


sorts on the


sample of the 22.75" diameter HDPE form I will be using as my #5


coil form. I


coated it with the Behr Super Build 50 and let it dry for 3 days.


They cylinder


had the top and bottom cut off so when I stepped on it to deform it,


it bent in a


very severe manner. The polyurethane product did not suffer at all


- absolutely


no cracks or separation was found from the form itself. This was


then repeated


about ten days later, again with good results. Id did wipe down the


form with


XYLENE to make sure it was clean prior to coating it, if that is of


any interest.


My coil form from 2 years ago still looks brand new with the same


product. (When


I sued my circular saw to section the form for recycling, the poly


coating did


fail.) Chuck Curran.


NEW. I have several coils that I wound over 20 years ago and coated


with polyure-


thane and they are as good and as nice looking as the day they were


dried. The


alternatives you mentioned; G.E. Glyptal and Dolph's AC-43 air dry


varnish, are


needlessly expensive when compared to either polyethylene, shellac


of varnish, all


of which work quite well. BTW there may be differences in


polyurethane finishes,


I used Zar brand, clear glossy, oil based. Alfred A. Skrocki.


My notes show - Use petroleum based polyurethane varnish. Prevents


PVC plastic


from reabsorbing moisture. Avoid water bases and milky substances.


- das.

[Sridhar.M.G]

MANAGER

Quote for AC43 Varnish Air dry