two box schematic

Eugene52

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Teknetics , Fisher , Discovery3300 and TIANXUN 19 kHz VLF Metal Detector

	Re: two box schematic « Reply #30 on: August 25, 2009, 03:53:33 pm »

	Quote:	Posted by ant
I just wondered who is Sasho .. that's Bulgarian , not Russian

Sascho is from Bulgaria . He has done great work over the years on many VLF designs . The writing in the previous post looked a little Russian to me , small mistake !! Shocked

Best Regards to all ..........Eugene

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	Re: two box schematic « Reply #31 on: August 26, 2009, 04:24:51 am »

Regarding to the above schematic .. the transmit coil schematics seems not very powerful , somebody tested this MD ?

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	Re: two box schematic « Reply #32 on: August 26, 2009, 06:29:12 am »

theman;
ant;
Eugene52;

Honest mistake, it IS Cyrillic. Spasibo

Just had to say that.

2 box.... am always interested. And it is 2 box for a reason, to keep good separation, between transmit and receive. Even a separate ground system, and batteries, can prevent unwanted signals from giving false indications. That is why I really do not like that '1box/2 box.'

2 box, way back when, was truly that, and the Tx signal was nulled by adjusting the Rx loop. Granted, pcb's have mitigated that, a bit. Maybe I am secretly a TRADITIONALIST, oh Dog!

I have a couple ideas I am working on, for 2 box, and have been sifting the simulator software, for something (friendly) that does not have a steep learning curve.... at 69 I do not have the time for that.

What we need, and maybe there is one already, is a 2 box forum/topic area.

goldigger

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	Re: two box schematic « Reply #33 on: September 15, 2009, 08:41:34 am »

Hello all...

Are there any two box tutorials? I am interested in the two box technique using physical orientation of the two loops for a null. I have seen a few schematics but was wondering if a document exists that outlines the frequency, power level, and other details that work best.

I am considering designing one but want to read as much as I can first... thanks

theman

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	Re: two box schematic « Reply #34 on: September 15, 2009, 06:21:01 pm »

	Quote:	Posted by theman
Hello all... Are there any two box tutorials? I am interested in the two box technique using physical orientation of the two loops for a null. I have seen a few schematics but was wondering if a document exists that outlines the frequency, power level, and other details that work best. I am considering designing one but want to read as much as I can first... thanks theman

As far as I have seen, 2 box follows the same general rules as other locators, in respect to the relationship between frequency and depth: lower frequency means greater penetration but poorer response to less bulky things, while higher frequency means less depth with somewhat increased sensitivity.

I do not recall any or if there were tutorials, with the 2 box that I first became acquainted with, the post WW2 White. I remember there was lots of info on how to null, but that depends on physical construction.

You can have a dozen ways to move the receive coil, but all you want to do is minimize the unwanted pick-up of the Tx signal, even if you can not zero it completely. They could be fixed, permanently, once a null is obtained and compensate with a threshold control, in the Rx for any variation.

If you have an 'alarm' system that has a threshold: you can null, for minimum pick-up and set the threshold, then you do not have to stumble along with your eyes glued to a meter.... supposing the alarm is an audible one.

First of all, the Tx loop is horizontal and second the Rx loop is at 90 degrees for a null, so it is vertical. A 2 box is really simple, being just a transmitter and a receiver. It is NOT good for small items but excels for larger, deep items, like something as big as a lunch box.... or a car? Or.... ore veins or deposits, depth depending on size.

goldigger

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	Re: two box schematic « Reply #35 on: September 16, 2009, 08:51:10 am »

Thanks Goldigger for the help. I wanted to make one since they are not as common to find and I already have others that are higher performance for regular searching. The deep/larger item target is what I am looking for so this design fits well. This winter I hope to build a unit with audio that is fairly straight forward and uses easy to find components. I have reviewed a number of the 'front end' of the 2 circuits -TX drive and receive- so new ideas would be in the back end.

I do work with PIC micros so I would like to incorporate one as the threshold detector and maybe make it auto setting - thats after the rest works.

It is appealing to me since it seems straight forward and more simplistic operation compared to IB or pulse.

later
theman

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	Re: two box schematic « Reply #36 on: September 16, 2009, 11:27:40 am »

	Quote:	Posted by ekitts
Unless Gary has put back up lately it was pulled last year. I have what he put up at the time, But he pulled it back off. Earl

Sorry, I have never been happy with the results of any 2-box detectors I have made.

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	Re: two box schematic « Reply #37 on: September 16, 2009, 03:25:38 pm »

	Quote:	Posted by theman
I do work with PIC micros so I would like to incorporate one as the threshold detector and maybe make it auto setting - thats after the rest works. It is appealing to me since it seems straight forward and more simplistic operation compared to IB or pulse. later theman

PIC? Why?

There is only a simple on/off and/or varying level signal, it would be a waste of a processor and an unnecessary complication for anything other than using the PIC to log data levels and GPS. Its not like there is 2 or more signals to watch. (There can be two, if designed for logging +/- levels, exclusive of GPS)

Its far easier to use alarms, that work at a field settable level. You can still log levels and GPS, additionally.

Why complicate a simple thing?

goldigger

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	Re: two box schematic « Reply #38 on: September 17, 2009, 07:58:10 am »

PICs simplify development for me - I work on coding PICs in unique sensor applications. A micro controller will allow the developer to do a simple function like compare signal levels and turn a light or buzzer on/off. Then with just a few lines more of code many more functions could be added like auto threshold settings and an algorithm that monitors the signal to show you statistical info. Plus on a development project, a micro allows many lines to be measured that would help to fine tune and understand the circuit function.

To be honest though, simple analog measuring and LED / proportional sound is what I am going for. I guess its easier for me to design/debug a project with a micro since I am used to it.

You are right that it adds complication over what is required though.

theman

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	Re: two box schematic « Reply #39 on: September 17, 2009, 09:05:58 pm »

	Quote:	Posted by theman
PICs simplify development for me - I work on coding PICs in unique sensor applications. A micro controller will allow the developer to do a simple function like compare signal levels and turn a light or buzzer on/off. Then with just a few lines more of code many more functions could be added like auto threshold settings and an algorithm that monitors the signal to show you statistical info. Plus on a development project, a micro allows many lines to be measured that would help to fine tune and understand the circuit function. To be honest though, simple analog measuring and LED / proportional sound is what I am going for. I guess its easier for me to design/debug a project with a micro since I am used to it. You are right that it adds complication over what is required though. theman

I DO like the idea of having a pic to monitor and log all readings... it might be a lot cheaper than a professionally made logger, which will not necessarily do what you want.... like add GPS, every second to 10 seconds. You can easily cover 2 to 2.5 feet per second and I understand a second is the fastest GPS update you can do.... for my purposes, every 2 meters (6.56ft) is the shortest and 10 meters (32.8ft) the longest.

If you can do that, there is a ready-made market, for you, right here on this forum. Lots of people have been looking for DIY loggers, simple, with lots of memory (SD cards are ideal.) I know, if you developed a board, with programmed PICs AND PARTS KIT, that also takes SD cards, I would buy a couple maybe up to 5 kits!

The reason for xtra kits is to retrofit things! Shocked

About the GPS, you do not need to re-invent the GPS wheel.... Tiny Trak IV, is the best there is, in my opinion. It can be made to report, by the logger holding the (intended) Push-to-Talk line low, while it logs, then do a 'save' of the GPS bytes, after the logger releases the PTT line.

The only problem there is, is the TTI,II,III,IV are all made to output at 300Baud/1200Baud, simplex of course, with semi-standard tones, and you need to get this converted to something the PIC can put in memory... so there are actually two processes, here: 1) the serial data, from the detection (by any equipment putting out 0 to 12v) which would be an ADC process, and stick it in memory; 2) a serial operation to take the translated GPS data, and stick it in memory, also.

It should be simple. However, I am not that good with PIC programming, or I would have made one.... long ago.

Tell me what you think. Google TT1,2,3 and 4.... download the manual and see what it does.

goldigger

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