DBP2010

Hi darkkitten,

after the first testing in field i decided to make a new front layout.
To play with the filter options it`s better to acknowledge the value of the filter settings.
Now i must say that the discrimination of the dbp in field is more easy to handle, better than i thought.

Here the new front:

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,13452.msg90000.html#msg90000

Excellent!! Well done.

d.


Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,13452.msg90172.html#msg90172

Hi Dennis,

thank you for the compliment. The depth is like Cornelius DBP2010.
For instance: 1 and 2 ? about 20-30 cm,bigger things up to a size of 10x10cm about 80-100cm depth.Very good values i never found in other pulsedetectors so long.

I made two coils.
The first one as in the original description: about 28cm diameter and 46 turns.
Second one has two separate diameters with inner and outer circle as you can find on pulsis webside: 

You are not allowed to view links.
Please Register or Login

I did this to find out which coil would work better in soil.
My DBP2010 works better with the simple variation and one diameter.

Perhaps Cornelius or Darkkitten do have more experience about coils and could tell us something about it?

Greetings,
sabloni

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,13452.msg93349.html#msg93349

Hi, ppl,

O.K. here is the ?coil story?:  the combined coil, made of two concentric coils, the inner one having from around ? to 1/3 of total wire length, connected in series and in phase, the whole system being in the same inductance window as one simple large coil (of the outer coil diameter),  is sometimes used with PIs in attempt to improve the machine?s sensitivity for small objects and pinpointing capability, usually, but not always at the expense of total depth.   To preserve the penetrating depth, magnetic field density gradient (away from coil) generated by larger outer coil should be relatively comparable with the gradient generated by a simple coil of the outer coil?s diameter (i.e. in the same magnitude). Since the no. of windings is fixed (by the inductance requirements of the system), the current flow threw both coils should be large enough.  In praxis and in my experience, this boils down to a simple rule; for coil systems of outer coil diameter between 30 and 45 cm the margin coil driving voltage is about 20V. Above that voltage no depth decrease will be noticed, below that, total depth decrease should be expected. A DBP2010 is no exception, running at 12V, simple coil will do better than combined one. Any average PI machine will be notoriously sensitive for small and larger items with coils up to 35cm maybe 40cm (depending on detector) diameter, above that  the sensitivity for small targets will start dropping noticeably. If one intends to build a coil up to, let me say 40 cm diameter, building an inner coil is waste of time on that agenda. Improvement of pinpointing ability may be a plus, however. In PIs with larger coils, small items might generate two signal maximums when passed over with simple coil, if not oriented correctly, each being closer to the winding rather than the centre of coil. The combined coil will produce one signal max. at the centre of coil at 90% of targets and three (two near the outer coil windings and one in the coil?s center), the one in the centre being the strongest in the rest 10% cases. After some period of experiences with PIs this too, becomes rather a matter of taste. 
Let me stress again, the PI machines are optimal for deep targets of say 8cm in diameter or larger, and DBP2010 can go as deep as 4m for large ones. Large simple coils (i.e. 1m x 1m ) works best. Using a PI as a coin shooter and small items seeker, is like using a sledge hammer to hammer small pins. Since the depth difference between a good VLF and fine PI  in average soil will be, in my experience, minute, the VLF should be a tool of choice for that. I have tested one of Minelab?s finest and my Miner4 on my backyard; there was no noticeable difference up to the coin size of 1 EUR coin (about 2 cm diameter), a very small difference (i.e. 1cm) for coins up to 2 EUR (2.5 cm diameter), and about 1 ? 2cm for silver coins up to 3.5cm diameter. Large silver coins up to 5 cm of diameter makes Miner4 better for some 5 cm. For larger objects than this PI starts to win fast and at some 8 cm of diameter of target the victory is undisputable. So for small items peeking, one can expect an average 2 cm (a week inch) more from PI than VLF. The cost for this will not only be the lack of solid discrimination and absence of depth assessment but one should be aware of metal objects the PI is rather blind to, such as foils, small gauge wires, small link chains (gold chains and jewelry), and objects where less conductive metal core is incased with better conductive shall such as some bullets, gold plated jewelry as well as modern 24 karat plated gold rings and gold jewelry (more and more companies are gold platting their products made of gold alloy to avoid possible allergic reactions). If anyone is interested, I can latter describe a couple of experiments to demonstrate this. I shall live to those more profound in electronics and magnetic fields to explain this.

Regards,
d.


Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,13452.msg93660.html#msg93660

Cornelius,

Dennis here, I'm sorry I forgot to include my E-mail address in my original request for the DBP 2010 information, retired brain fade I guess. 

Take care,

Dennis  /  balsawood@embarqmail.com

Linkback:

You are not allowed to view links.
Please Register or Login

http://www.thunting.com/smf/index.php/topic,13452.msg93842.html#msg93842