DP interesting beeps

[1843]

T2&T3

Hi all,
What do T2 & T3 do in DP??? Are those really need?
I omitted them; Only effect which I saw is they limit sample at 30us...(don't allow for less delay)
We can increase R7 instead them...What are your ideas?
Regards

[okantex]

Yes Affter learning how to play with pots ,problem is over.
I worked with 45cm coil.I draw it over plants .twere only onw signal . it can be metal. do not it is false signal.but ground was dry ,also plants were dry.
ı sstill have to try it after rain.
over a know target. 140cm dept.
now ground is full of long wheat plants .when I pass 15-20cm over target no signal.
but when I push coil to ground over target raslly gets good signal.
I tried it over other plants to chech if it is false or not.
yes it was real signal.

I think I will use big coil 5cm over ground next time.no more.

why? do not know.
getting close to ground increase detection.

[Geo]

Hi all,
What do T2 & T3 do in DP??? Are those really need?
I omitted them; Only effect which I saw is they limit sample at 30us...(don't allow for less delay)
We can increase R7 instead them...What are your ideas?
Regards

Hi 1843 .
I dont know exactly and i have not time to put it to the scope. But as i see the schematic T3 and R16 are parallel with the feedback resistor R17, so when the signal is strong T3 go on....... gain of D4 (LF357) go lower ....T2 go on and play with sample but i dont know what it do (increase...decrease or what...)
If you will connect it to a scope please tell me what you will see
Regards

[ivconic]

OFF subject....

I might be a bit off subject, but here some i started to write the other night...and didnt finished...I am in the middle of chaos here, lot of other things to do so excuse me cose cant continue with this subject .....at lest for couple days...Regards!

....Yes i agree. It will be good to reconsider again some very good solutions from other projects.
For example i can take, as example, delay stage from Hammerhead, where main delay can be adjustable
from 10uS to 75uS and additional delay from 75uS to 350uS. By this Hammerhead can be pushed to
work with rich variety of quite different coil designs under various working conditions, of course
paying attention on frequency (Geo, this is yet very important!)...In case of Hammerhead, frequency
can be set in range 900Hz-2.3kHz. I am wondering; what should be if Hammerhead frequency is set
much lower than it is; let's say 400-500Hz or even lower 200-300Hz ?
Main reason i choose DP to build and not Hammerhead is the working frequency, and fact that DP is
designed to go much deeper(on large items) than HH. On the other hand HH is suitable for nugget hunting,
just as GS serie...I presume also suitable for coins and small items..
We should make clear partitioning between two main PI categories. Further, man have to decide
what should be his interest to use. Either deep penetrating, "slow" PI for detecting large items using
mostly larger coils, either "fast" and "shallow" PI using small coil designs, very useable in coin and
nugget prospecting.
I think we cant have both in one PI design. Mostly due design limitations itself.
I think Carl's initial idea, designing HH, was to make sort of educational platform, by including
almost complete control on signal during processing. That's why HH is so good equiped with trimms,
test points and stuff.
So let's back to 2 main Pi categories. Rules which can be applied to one (considering coil specifications),
for sure can not be used on another. I think quite oposite....Why? How?
Let me give you an example;
In the past,experimenting with different PI coil designs, i made 2 identical coils. But, one i made
without shielding, and another with.
Both were connected on DP and testing showed greater depth and better perfomances with coil without
shielding???? How come? Why?
I am 100% sure that results would be oposite if i used HH instead DP testing those coils...
Coil with shielding would have better perfomances than other one.
Yes, sample delay, width, frequency, shielding or not...are determinant factors which lead us how to
make proper coil for our PI.
I am also very interested in using DD coil design with DP. So far i didnt test it. I think DD coil
will be more effective on highly mineralized soil...Maybe it is good idea for you Okantex?
Right now i am occupied much with something else, dont have enough time to deal with this.
If anybody already have experiences with DP and DD coil, it will be good to post those here.
regards!
...........

[okantex]

As I know,Lorenz deepmaxX3 uses this DD coils for ferrous nonferrous discrimintion.

[1843]

Hi Geo,
I connected it to scope and saw what I mentioned before. It refers to sample time...

I changed all my DP capacitors to polyester and tantalum, also used a 10000uF in parallel with batt,
Now it works very stable...!!! I am happy!

Best regards

[Guard]

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.

[okantex]

signal for gold.
Negative part is for TX part. Positive part is flyback and RX complextion.


Can you measure lf357 output.

İs it same as this Picture.
I mean is flyback at lf 357 output positive or negative.?
And if posible can you measure voltage with big metal infront of coil.

[okantex]

Hi 1843

[1843]

Hi Okan,

I hope this helps,
Regards

[okantex]

great thanks
what an increadible speed?wow only 2 minutes