Delta Pulse

[1843]

Thank you Eugene, The secret of deep detecting of Deltapulse is that section... I think that the gain must be much much higher... +10000(?!)

It is confusing for me... The D7B has two R_feedbak with diode coupled... don't know anything!!!

Kind regards,
1843

[amtech2005]

Delta Pulse

Hello 1843 , Now is the right time for us to answer you , last time I checked there was a Record 650 users here on Geotech Today !!! Any way the CD4066 Quad bilateral switch ON the gain should be at zero on the TL062 Linear JFET. With the CD4066 Switch off gain of the TL062 will be at 10 or so.Whats between pins 1 and 2 and pins 6 and 7 determine your TL062 circuit gain. For me , having test equipment is much easier than writing formulas and equations........Anyone else is welcome to comment here !!!! Take care all ........Eugene

[1843]

Hi all,
How much is the total gain of the following circuit...?
(When the switch is open and when it is closed)



Thanks in advance,
1843

Hi,
directly ? you can...pinout is about the same (though balance stuff different...) but I think is not so good idea...

though 318 has high slew rate it's not so quiet as an 356 or 357 could be... so test before install... you could lose "some" stability.

Kind regards,
Max

thanks, I try LF356!!!
excuse me it's possible change TL062>TL082?

[Max]

good day to all. I am realizing the deltapulse. is possible to replace LF357 with LM318? Thanks for the answers
excuse my english

Hi,
directly ? you can...pinout is about the same (though balance stuff different...) but I think is not so good idea...

though 318 has high slew rate it's not so quiet as an 356 or 357 could be... so test before install... you could lose "some" stability.

Kind regards,
Max

[aft_72005]

Hi
You can use LF356 instead of LF357 ,also I compared these two on delta pulse .
LF 356 had good result with lower S.R. against LF 357.

good day to all. I am realizing the deltapulse. is possible to replace LF357 with LM318? Thanks for the answers
excuse my english

[porkluvr]

... IT SAYS YOUR LOCATION IS 130 MILES SOUTH OF CARL !!!! I HAVE BEEN LAUGHING FOR OVER 30 MINUTES. THAT STATEMENT HAS ALOT OF HIDDEN HUMOR , I AM LAUGHING WITH YOU, NOT AT YOU.

Well, you can laugh with me or laugh at me - whatever the case. If the shoe fits, I will wear it. I have made some dumb posts in the past and I will probably make more bonehead posts in the future. Sometimes I don't think- just open mouth, insert foot.

'Fer instance: just today realized that I have in the past erroneously extolled the virtue of using LT1012 in place of two LM308s, but, that's not a very good idea because the LT1012 is a single opamp. Yep, I did that.

But anyway, Noemio: look at BB Sailor's "Fast Coil" article, here:

http://geotech.thunting.com/pages/metdet/projects/fastcoils/FastCoil.pdf

Also, Dave Emery's article: http://geotech.thunting.com/pages/me...planar_150.pdf

I live near some played out gold mines in Charlotte, NC. So, even though the Delta Pulse may be a good machine, I need a PI machine with faster response and receiver blanking - to find SMALL gold, if I'm lucky.

(I think that Dave Emery lives about 25 miles away, maybe I'll ask him if I can use his lab for set-up when I get up the nerve.)

Carry on Deltapulse!

[amtech2005]

Delta Pulse

GOOD MORNING PORKLUVR !! I AGREE 100% THE MAGNETIC FIELDS DO CANCEL OUT , BUT MY QUESTION IS DOES A NEGATIVE SIDE OF THE FIELD CHARGE A TARGET MORE THAN THE POSITIVE SIDE OF THE FIELD OR DOES IT HAVE TO DO WITH THE METALS AMOUNT OF FREE ELECTRONS IT CAN HANDLE??? HAS ANYONE THOUGHT OF THAT ?? . BUT THE MAIN REASON I REPLIED IS AT THE TOP RIGHT CORNER OF YOUR POST IT SAYS YOUR LOCATION IS 130 MILES SOUTH OF CARL !!!! I HAVE BEEN LAUGHING FOR OVER 30 MINUTES. THAT STATEMENT HAS ALOT OF HIDDEN HUMOR , I AM LAUGHING WITH YOU, NOT AT YOU. IF I LIVED THAT CLOSE TO CARL I WOULD POST THAT INFORMATION ALSO !!!. ANYWAY YOU ARE VERY LUCKY FOR MANY REASONS , A TECHNICAL GURU , SCIENTIST, LIVING SO CLOSE TO YOU... AND ALSO IF HE EVER HAD A GARAGE SALE OF HIS METAL DETECTOR'S ,YOU ARE RIGHT THERE AND DO NOT GET A SPEEDING TICKET !! . YOU HAVE A GREAT SUNDAY .....EUGENE

[porkluvr]

... your zig-zag wires add comparatively little inductance compared to the added wire length.
.

What I was trying to say, is: your wires crossing at almost 90 degrees will have their individual magnetic fields partially cancel each other.

Apply the Left (-or right-) Hand Rule, to visualize. Where your fingers point at each other will be magnetic field cancellation.

[porkluvr]

Hi all,

I just finished to build this coil but it doesn't work good on my DP.
Very difficult to find an adequate value for dumping resistor, a lot of instability during work an a lot of ground effect.
It's 25 cm in diameter with 32 turns. It developes (only) 240 µH and 1,2 ohm.
Any comments or suggestions?

(Just curious) what gauge wire did you use?

I think your coil will have more capacitance towards the ground because your zig-zag wires add comparatively little inductance compared to the added wire length.

Additional parasitic parallel capacitance would cause the coil's decay curve to be relatively wide, compared to the decay curve of a coil with a more direct wire path.

[Geo]

Hi all,

I just finished to build this coil but it doesn't work good on my DP.
Very difficult to find an adequate value for dumping resistor, a lot of instability during work an a lot of ground effect.
It's 25 cm in diameter with 32 turns. It developes (only) 240 µH and 1,2 ohm.
Any comments or suggestions?

Very good work.
DP needs more inductance and biger DC resistance.
As an example 700... 1000 uH amd 3....4 Ohm resistance at the coil connector.

Hi all,

I just finished to build this coil but it doesn't work good on my DP....

Excelend work.
Did you try 2-3 om resistor in series with fet ?
Did you try up to ... 300 pulses ?

[Noemio]

pancake coil

Hi all,

I just finished to build this coil but it doesn't work good on my DP.
Very difficult to find an adequate value for dumping resistor, a lot of instability during work an a lot of ground effect.
It's 25 cm in diameter with 32 turns. It developes (only) 240 µH and 1,2 ohm.
Any comments or suggestions?

[1843]

Hi,
I just read the LF357 datasheet. It says that the maximum input voltage is 100mV higher than Vcc.
The max input voltage for LF357 is about 1V higher than Vcc in Deltapulse . How doesn't it get destroyed?

Regards,
1843