TOTeM confusion

[Mike(Mont)]

Or is it "Total confusion"?

First off, I have not built the TOTeM project so I don't know for sure.

Okay, I think something is not right and I just wanted to put this out so you can decide if I am right or I am wrong. Sorry didn't post the diagram that shows the null lines for the ferrite rod. It is figure 7 in the "Pistol Detector TOTeM Project". In the diagram the null lines come off the edge of the coil (right at the windings) at 45 degrees. i do not think this is right but I could be wrong. I think the null lines should come off 45 degrees from the CENTER of the TX coil. For a four inch (10cm) diameter coil, that's going to move the ferrite rod back about one inch (about 2.5 cm). Tell me if I am right or wrong.

If I'm right, this is my New Year's present to the forum. Can you hear me now?

[Mike(Mont)]

"Ah, but then one night in some empty room
Where no curtains ever hung
Like a miracle some golden words
Rolled off of someone's tongue

And after years of being nothing
They're all looking right at you
And then for a while they'll go in style
On 16th Avenue."

[Mike(Mont)]

I don't know about other Pistol type locators, but if they use a ferrite rod in the null line, then you might want to see what happens.

Just so you know, my contraption works a little like the Pistol type locators. I've been working with it for over a year and that was part of my fine tuning to get the exact line--otherwise my line to the target was not correct. Now I admit I do things differently so I'm not saying I know for sure how it will work on your locator, but I'm sure enough to post this. Like 99% sure. Put it this way, when I used the null line in the diagram, it would not point at the target.

So what i don't know is how it will affect your locator. I realize most Pistol types have the ferrite on the centerline above the coil so it's not going to change the direction angle to the target, but maybe you can tune it sharper and get much better range. I don't know but if it was mine, I would certainly try this. What I have read, these Pistol types get pitiful range, just pitiful. So whatever.

[Qiaozhi]

Or is it "Total confusion"?

First off, I have not built the TOTeM project so I don't know for sure.

Okay, I think something is not right and I just wanted to put this out so you can decide if I am right or I am wrong. Sorry didn't post the diagram that shows the null lines for the ferrite rod. It is figure 7 in the "Pistol Detector TOTeM Project". In the diagram the null lines come off the edge of the coil (right at the windings) at 45 degrees. i do not think this is right but I could be wrong. I think the null lines should come off 45 degrees from the CENTER of the TX coil. For a four inch (10cm) diameter coil, that's going to move the ferrite rod back about one inch (about 2.5 cm). Tell me if I am right or wrong.

If I'm right, this is my New Year's present to the forum. Can you hear me now?

The diagram in the TOTeM project is correct. The magnetic field is strongest close to the windings, and weaker at the center of the coil, as shown by the Biot-Savart Law.

[Mike(Mont)]

No problem here, i ain't building one. i admit I am not up on the electronics formulas but the center of the coil definitely has a concentrated field.

[Mike(Mont)]

One thing for certain is I don't know much about it. My 99% certainty level has dropped significantly. Like i said, my contraption is different.

[Mike(Mont)]

I guess I shouldn't have said anything

[Mike(Mont)]

I admit there is no question it is not the same for the Pistol type locators. So I'll try not to confuse things any more than they already are. Best to stick with the plans.

[Mike(Mont)]

This post has been deleted. I tried to help. These Pistol type locators are not right anyway so no sense to try to fix.

I throw my hands up into the air. At what point does this become a hoax? Qiaozhi says he encourages experimentation, but as soon as someone offers a suggestion, they are shot down. What I am saying is not in any electronics textbook. I understand most people think that is all there is to reality. I say B.S. So I give up. Bye bye.

[Qiaozhi]

This post has been deleted. I tried to help. These Pistol type locators are not right anyway so no sense to try to fix.

I throw my hands up into the air. At what point does this become a hoax? Qiaozhi says he encourages experimentation, but as soon as someone offers a suggestion, they are shot down. What I am saying is not in any electronics textbook. I understand most people think that is all there is to reality. I say B.S. So I give up. Bye bye.

All you need to do is connect a coil to an oscillator circuit, as shown in the TOTeM article, and place a ferrite coil along one of the null lines shown in Fig.7. With a scope attached to the ferrite coil, or (if the TX oscillator is in the audio range) an amplifier driving a speaker, and you can easily locate the null. This null line radiates out away from the coil as shown. In fact, there are really two null cones surrounding the coil. Try it ... you'll find that it's not just a theory. The null lines are really there.

Also, the magnetic field is not concentrated at the center of the coil. The field strength falls off with distance, and is weaker the further you get away from the coil winding.

By the way, I'm not "shooting you down", but simply correctly your misconception.

[Mike(Mont)]

Yeah, that's what I call "misapplied theory". Coil geometry dictates the null line. So a null is where it is, not where somebody says it is. I measured mine with a protractor. I really doubt is was by chance that it ended up 45 degrees from the center of the coil. So I will concede that your coil is "different". But looking at the diagram of the enclosure (sorry, don't have the figure number handy) it sure looks like it is 45 degrees off the center. So, whatever. I'm over it.

[Mike(Mont)]

I swear i saw another figure but I can't find it. Figure 2 is pretty easy to see the angle. I realize that is not the TOTeM. Anyway, guess I should apologize for the "hoax" comment. I can see you spent a lot of time developing this.

[Mike(Mont)]

Oops, my confusion runs deep. I now recall the original shown in Figure 2 has the two ferrite rods (coplanar) so I guess I got that one wrong. Well, i hope this is the last post from me on this topic.

[Mike(Mont)]

i don't wish to dwell on this topic, but it has occurred to me I am using a different "everything" on my contraption. Different frequency, coil, transmitter, receiver, receiver coil, everything. Like the Dylan song "Everything is Broken". So maybe that could explain some of the discrepancy.

https://www.youtube.com/watch?v=ZXgtKUpu4Sw

[Mike(Mont)]

My curiosity has impelled me to look into this null line a bit more. So I built a different (round) TX coil for my locator to see what i could see. I'm getting the same results as previously reported--45 degrees off the center of the coil. I guess that rules out coil shape as being a factor. Probably should say none of this is "scientific", just my own addled observations. Not trying to nit-pick here, just want to find out why things are not the same, with the hope that maybe i can find some "issue" causing the stifled performance of these pistol type locators.

I know people say to keep conductive objects away from the TX coil as this creates eddy currents that distort the TX coil field. I would suggest this is the area to examine more closely. The original pistol locators had the coil mounted up away from the electronics. I don't know but that's where I would experiment. Well, anyway, just a thought. I don't have one to experiment with. Shouldn't be that difficult to find out, just mount the coil up above the ferrite the same distance as it is below. Much like the original only a bit higher. Yes, it will be more bulky but if i had one I would try it. Like Donald Trump asks "What do you have to lose?" I'd say this much, it can't hurt the performance.