Delta Pulse

[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

[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 =)

[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 ?

[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....

[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.
-------------
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?
-------------
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.

[6666]

Thanks KT315 you have a good archive.

[jladre]

Test result of 1mh and 435uh coil no big difference what you got in 1mh coil are more wire, more weight and more effort in making...hahahaja.. you are right kt315...

[jladre]

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

Hi mohandes! For your 1.2x1.2 meter coil how many turn of cat 5 you use and what guage?

[6666]

Here is a table for 1mx1m coil, as the coil gets bigger the size of the wire gets bigger, but the number of turns reduces.

[jladre]

Here is a table for 1mx1m coil, as the coil gets bigger the size of the wire gets bigger, but the number of turns reduces.

Thanks 6666... it is very useful for me.

[mohandes]

i make all coil with cate5 or cate6.
for 1.2m coil i add 2wire like that and get 540mkh and 3.2ohm.good result .
but i make 1.45m coil with same cate6 and get 458mkh and 2.8ohm.but the same plate ,1.2 meter coil get better.
i use 560ohm for damping R for all coil.
regards

[jladre]

i make all coil with cate5 or cate6.
for 1.2m coil i add 2wire like that and get 540mkh and 3.2ohm.good result .
but i make 1.45m coil with same cate6 and get 458mkh and 2.8ohm.but the same plate ,1.2 meter coil get better.
i use 560ohm for damping R for all coil.
regards

Hi mohandes! Have change c4, c5 and r7 of your board? Im a little upset of the result of my varios coil which have all bad depth.

[kt315]

DP with short FIRST STROBE DELAY.

Hi all.
I made 2 delta pulse with delay 5-80us, with unshielded coils 50,65 (1mm/18t),1x1m,2x2m,2x3m (R7=3.3K, C4=1.5nf, pot=50k, vcc=12v, I=120mA, 10000uF to irf, 1om/5w from irf to -vcc ).
I agree that delta pulse is a very good pulse detector for deep and big objects, BUT it is also a very-very good machine for small objects.
I also agree with Ivconic and Geo that if you have any other detector you have to seel them and with the money you take you build 10-20 delta pulse .
With 65cm coil i have sound from 55cm and with 50cm coil i have sound from 50cm for a coin of 0.5 euro (delay 5-30us) !!!
And with the same coil i have sound from 2.3m for 18liter olive oil box.
I have the same problem with wet soil when i use delays below 30us especialy last week who rains continiously.
I change my old battery 12v/1.2A with 3x6v/1,2A for 18v and inside i stabilize with 7812. Now i have a more stable machine but i take out the batteries to my back bag because the dp sounds when the batteries (metal) are near to 65cm coil. For stick i use wood 1.2m from broom.
My big problem over a year ! is that d.p. is not stable and it lose the sound 1-5hz requiret for sensitivity (threshold, capacitors problem ???). I change R42, remove R37... but the problem insist.
Anybody knows what can i do to have condinuously sound ???
I also want to know where you set the second delay in D3A and if this is correct R9+Rpot * C6 =ms (102-852ms).

Best regards to all and continue the good job.

[jladre]

Thanks kt315 for this statement, it give me motivation to continueworking my dp so that it may work better

[kt315]

to work better DP will be not. every nails, every pins, every ferro and un-ferro garbage will be yours. only clear gold fields, without hot rocks and ferro, like you see them in Australia, without battles' and wars' metal, with gold nuggets everywhere will give you real mega extra advantages. anotherway you get only constant head pains (be cause your unwillingness to learn PI principles, be cause your nature laziness to learn something new).