Inside The Metal Detector Book

[Mike(Mont)]

Figured this topic needs it's own thread.

I got a copy of ITMD (Second Edition) yesterday and read it until my eyes and brain got tired. Actually my brain was tired before I ever started reading. So maybe "overload" is a better word. Learned a lot especially about the Induction Balance. Trying to relate all this to the contraption I am working on, and was hoping to incorporate some ground balance into it. So trying to learn about the GEB ground balance. I'm not too savvy on this and it's "learn as I go". My main concern centers around the oscillator being sine wave instead of the square wave my device uses. Looks like the GEB converts it to square wave, so maybe I can cut one step out of the process. But I need to temper my enthusiasm because my motto "Nothing is ever as easy as it first appears." Well, I just read through it one time and really need to go back over it "with a fine-toothed comb". Yeah, there is some good material there and I give it two thumbs up. Haven't even got to the pulse induction section yet.

[Mike(Mont)]

For now I am trying to use the sine wave and see what happens. Looks like it will work. I have a long ways to go with all this. Still don't know if I can work with the 10kHz. Really need below 3kHz. So don't know if I will need to change the "GEB and DISC Sample Pulse Generator circuit (page 91 Figure 9-7). I suspect there is some filter/pass there that I don't know enough about. Anyway need to do a lot more reading before anything happens.

[Mike(Mont)]

I read through the main section on Pulse Induction (not the projects) and learned some more useful stuff about square waves. And enjoyed reading it. Also went back through the Induction Balance ground balance and discriminator section, and started to realize it is probably too complicated for me to modify. Maybe that's why no one has replied to this thread. I'm just thinking everything revolves around a specific 10kHZ system. At least if I am correct, it probably means everything would need to be changed and tested and then may only work for a different specific frequency. That's way beyond my knowledge (and skill) level. Well, some day I might dig in but I don't see that happening anytime soon. But never say "never". I mean I still think it is doable, just not by me right now. Probably would need some help from someone who knows WTH they are doing. Come Spring time I might be singing a different tune if I find out my contraption is not doing well.

[Mike(Mont)]

Certainly no expert here but I am learning and this book has sparked my interest in electronics. So have been doing some outside reading on voltage dividers, filters, etc. Not saying I can speak the language yet, but starting to see some things about how capacitors work in filters. So still pretty much in the infantile stages, but gotta start somewhere. It's amazing what a little reading and head scratching can do. Kinda surprised not many other comments on your book. I did read one a while back, somebody said it was good. I understand most of the concepts but need huge work on the microprocessor section for the pulse induction. But that's for another day. This book is a keeper for sure. Thanks George and Carl.

[Mike(Mont)]

Of course I found all the concepts valuable but for me I really like where you explain the circuits, etc. then explain what happens if you change it or use different coil, or whatever. That really gives a deeper understanding at least for me. That good is loaded with good stuff.

[Carl-NC]

You shoulda got the 1st edition, it has the chapter on LRLs and the pistol detector. Of course the PD is online and free now.

[Mike(Mont)]

Yeah, they are a real collectors item. Big money for a used one. I downloaded the TOTeM plans. I still might do something with it, you know hack it like i do everything I get. But I don't know how to do it yet. If I was to change the frequency on the receiver could I get by just changing the ferrite antenna?

[Mike(Mont)]

Carl, I'm probably better off if I didn't read the LRL section.

[Mike(Mont)]

It's called bias. You ain't the only one. Pretty much every LRL manufacturer says the others don't work or at least not as good. Dell Winders is one of the few who doesn't follow that line of thinking. He did testing on many devices, even said the Mineoro works if tuned properly and locating conditions are okay.

No need to spend any time on the TOTeM receiver question. I don't plan to do anything on it in the foreseeable future. Don't ever see getting past what I have on my plate right now.