Delta Pulse

[kt315]

Posted by: Eric Foster

Beachscan
Posted by: Eric Foster (---.ipt.aol.com)
Date: April 6, 2000 04:35PM
This is an example of a PI detector that breaks with traditional principles to some degree. Instead of pulsing a high current through a low resistance and low inductance coil it pulses only 0.2A peak through a 10 ohm coil that has an additional 39 ohms in series. The coil also has an inductance of over three times the usual amount but we are still able to sample at the magic 15uS for use on a wet beach. The MosFet can be a small one with a relatively low voltage rating and the mean dc current taken from the batteries is only 65mA giving good life from 8AA cells.
Eric.
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Re: Beachscan
Posted by: Jeff Kinzli (---.cisco.com)
Date: April 6, 2000 05:42PM
So Eric, what does this non-traditional PI gain by going to a higher resistance coil and lower current into the coil? Is it better around RF interference or something?
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Re: Beachscan
Posted by: Eric Foster (---.proxy.aol.com)
Date: April 12, 2000 11:33AM
Hi Jeff,
Just an alternative way of doing things really. The low pulse current means that you can switch faster and sample earlier; except in this case the inductance of the coil is much higher so you end up at square one. Noise performance is no better and no worse. The higher pulse frequency results in more samples into the integrator in a given time but the greater number of turns on the coil means more noise to average. The reason for using this technique in the Beachscan is the small 4 pin DIP Mosfet and the small reservoir capacitor. This saves quite a bit of space on a high density board.
Eric.

[Silver Dollar]

1000uH inductance has coils FOR THE NEW GENERATION
of PI detectors...working at hight frequency (10kHz or 10 PPS).

Wow That's the first time I have heard that. I though higher inductance was used
for big objects or deep detection (like 1mx1m coils). You would miss small objects
as the higher inductance has greater resistance to change so needs to be pulsed
slower....

[bernte_one]

i had the cs4pi here for testing - terrible
heavy search hed , bad depth performance

nothing against eric
but something was wrong there i remind something like peak pulse of 90v ?

[kt315]

you try to overload your head by absolutely needless knowledge. you are misleading something. 1000uH inductance has coils FOR THE NEW GENERATION
of PI detectors done by Eric Foster - C-Scope CS4PI C-Scope CS6PI C-Scope CS7 etc, working at hight frequency (10kHz or 10 PPS).

NO relation to Delta Pulse that uses 'classic' 350-500uH coils. but if you so want to check 1mH coil, do it and tell us the result =)

[jladre]

Hi kt315... i have read so many post and 1 thing confused me..in the schematic it is mention that it need 1000 uh inductance and some other post in the forum suggest that it must be 400-450 uh.. i want to know which is true for a 1x1 meter coil.. thanks

[jladre]

cat 5 is not so good be cause a trasfer capacitance not low, but if you have not access to more good wire cat 5 may be decision.
for DP with big FIRST STROBE DELAY the cable's transfer cap maybe is not so important, but for gold nuggets for small coil and small FIRST STROBE DELAY
you have to use anything another wire (in fat isol with low cap and low inductivity).

Thanks kt315...

[kt315]

cat 5 is not so good be cause a trasfer capacitance not low, but if you have not access to more good wire cat 5 may be decision.
for DP with big FIRST STROBE DELAY the cable's transfer cap maybe is not so important, but for gold nuggets for small coil and small FIRST STROBE DELAY
you have to use anything another wire (in fat isol with low cap and low inductivity).

[mohandes]

Hi mohandes can give more details on how many turn of the cat wire and how deep is the maximum detection for that coil..tnx

hi
i use cate 5 and series he wires , i can detect 50*50 metal plate in 3.20 cm in air.
regards

[jladre]

Hi mohandes can give more details on how many turn of the cat wire and how deep is the maximum detection for that coil..tnx

[mohandes]

Hi! Has anyone her tried to use a enameled copper wire for 1x1 meter coil for delta pulse? How does it work?

use cate5 and with 1.2m*1.2m.it will work .

about irf740 , what current is produce ? or better say what current coil need in max power (then irf740 produce it)?

[jladre]

Hi! Has anyone her tried to use a enameled copper wire for 1x1 meter coil for delta pulse? How does it work?

[kt315]

2A - some kinda 'universal set place for many types of pots'. ignore them, it was need for P-CADing. those pins are mounting holes at pcb for the pots.
3C - points for to connect the wire to housing shielding layers.

[Davis9000]

Hello, I have few questions about Delta pulse schematic(they are in picture).

[jladre]

Tnx mohandes my friend

Tnx kt315.. im reading those article now

[kt315]

try to read more about Pulse Induction principles. learn them much. all you are able to find all is the info concerning relating to DP, because DP
is classic PI detector, with classic PI detector architecture. without those basic knowledges nobody is not able to give you due the recommendations
besause YOU ll not be able TO GET the info (the school child is not prepared and left the school to be idiot).
except frequently replies 'set the knob SENS on max position for the max depth', that is absoliutely contra productive and does not give you the right way.
at first step, learn the article of Carl Moreland on Hammerhead PI. for much things it will be sure enough for a people like you.