VLF MD (by Sascho - Varna)

[Leto]

Hi,
Nice work Leto!
You got it!
Can you tell me what are other Transistors?
I will try to prepare a picture with labeled parts.So the things would be easyer.
If I wanna wind 20 cm OO coil for this detector with 0,3 wire how much turns should I try?
Thanks
I will try to make and try this one in next couple of days.

Hi tiktak
Device can be adjusted to extreme sensitivity (same for TGS as max reported ) too much to report here.
But this are just air tests and unshielded coils.
For 20cm coils you can try with same 100 turns and if inner diameter is bigger than 21cm probably 96 for Rx and 48/24/24 for Tx. Also other wire/turns will work for sure, but changing Tx section of L1 coil will give you different output frequency.

Lets wait what Sascho has to say in english...

[N@SKO]

Sasho ima6 li Skype?
Ima nujda ot malko pomo6t!
V proces na rabota ne trqbva li da se pravi
nulirane i nastroika na fazata pri promqna na temperaturata?

[ivconic]

Hi tiktak

Device can be adjusted to extreme sensitivity (same for TGS as max reported ) too much to report here.
But this are just air tests and unshielded coils.
For 20cm coils you can try with same 100 turns and if inner diameter is bigger than 21cm probably 96 for Rx and 48/24/24 for Tx. Also other wire/turns will work for sure, but changing Tx section of L1 coil will give you different output frequency.

Lets wait what Sascho has to say in english...

Nice work Leto.
I am affraid you will face huge instabillity on the ground. Air test proves nothing. Especially with unshielded coils!!!???
I would never suggest nobody to even switch ON any detector with unshielded coils. Might confuse you much and give you whole wrong ideas about metal detectors. Further you will have a lot of problems to understand why your detector is not showing neither 30% of perfomances, showed previously on the bench with unshielded coils...
Be sure that once you put shield on your coils and adjust GEB to work without falses, best you can get would be 30-50% of performances you have now.
Once i had dear friend Jackdetect;his main problem was cose he never left workshop and tried his detectors on real field,under real conditions. So his detectors worked fantastic in the air in his workshop, but very bad outdoor,under real conditions! Once i told him that, and he didnt beleived me,actually he was pissed off on me...
For everyone here, i can seriously suggest to go outdoor and fully test detectors on the real ground. Only detector with few or no falses at all IS REAL DETECTOR. Detector with excellent performances in THE AIR and a lot of falses on the ground IS NOT DETECTOR BUT PIECE OF JUNK, totally unuseable in real world.
Now, i am not saying that this Sasho's project is bad. Not at all! I am only saying that your experiencess with it's performances means NOTHING yet.
Until you put shield on coils and go outdoor and adjust GEB to produce NO FALSES at all. Than please come here and report. I am looking forward to see your experiences.
Best regards!

[ivconic]

In addition i would only say that TGS could detect 2cm coin at 70cm distance in the air with unshielded coils. Later when coils were shielded and GEB adjusted to produce no falses at all, same coin can be detected barely at 27cm in the ground and 36cm in the air...
Is this illustrative enough?

[Max]

In addition i would only say that TGS could detect 2cm coin at 70cm distance in the air with unshielded coils. Later when coils were shielded and GEB adjusted to produce no falses at all, same coin can be detected barely at 27cm in the ground and 36cm in the air...
Is this illustrative enough?

Hi,

Ivconic... my friend... if you tell they these things they will start think you are crazy !

They will be much disappointed of other BIG MONEY detectors !

I just stopped posting about TGS performances for similar reasons

BTW How are you ? I hope you are well.

Best regards,
Max

[tiktak]

Hi,

Hi,
Leto.
Thanks.So I will try 19,5cm former TX=100w 50/25/25 and RX=100w wire 0,30 mm.
But still cant trace scheme and see where to place what.
Have you changed the places of TX points or they are like on scheme?
Pleace give one closer picture on finished PCB.
I am almost ready to begin soldering elements.
Can I replace LM2930-8 with 7808 arent they the same?
For transistors near TX I should use 2N2907 right?What about other 3?
And we have 1N4001 and 1N4148 for VCO and whats the other one 1N4001?
I still cant understand what change have you make from the look on the PCB that we have to make it work?You have mooved one resistor but which?
I have to now so I can make changes now?
How did you null this coil?
Thanks
Onece again EXELENT work!!!!
I cant understand why Sasho don't post here?
Maybe he isn't avelable now?
Last year he have helped here dayly.
I am curies how much diferent is nexus actuly?Maybe in some values.

[ivconic]

Hi,

Ivconic... my friend... if you tell they these things they will start think you are crazy !

They will be much disappointed of other BIG MONEY detectors !

I just stopped posting about TGS performances for similar reasons

BTW How are you ? I hope you are well.

Best regards,
Max

I just wanted to point on mistake he made cose testing coils without shields....

I am so so... yesterday i was under doppler, examined my liver. Well liver is fine, but i do have 2cm "rolling" stone in my gall-bladder, causing me a lot of pains. Damn. Need to wait for some time and than operate it. I was thinking to totally remove whole gall-bladder, not only stone. Further it will solve all problems. I can drink and eat what ever i want without extra precautions.
I will see...
But i am not telling this without reason;
while lying under doppler i payed attention on it and examined it carefully.
A strange idea occured to my mind; can we make diy doppler and try to use it in prospecting??? Ha?
Skin,organs and bones tissues are closely than many soils i do know. How come that tiny ultrasound can penetrate tissues and can not soil?
Is there anybody,ever tried or experimented with doppler so far?
This question can look pretty naive...but hey, what do i know? I never had any experiences with it so far...
Any experiences?

[J_Player]

Hi Ivconic,

Using doppler sounds like a good idea to locate treasure under the ground. People have asked this question in the forum before. Here are links that show the answer Carl-NC gave:
http://thunting.com/geotech/forums/s...ad.php?p=57980
http://thunting.com/geotech/forums/s...ad.php?t=10870

From What Carl says, the problem is to couple the ultrasound to the ground. If we can find a way to get a good coupling to the ground, then I believe we must also change the sound frequency and increase the power in order to get a usable response to treasure targets. The sound may travel through dense soil and reflect back from many things like rocks, tree roots, and other things that may be mistaken for targets. Maybe we would dig many holes to find rocks and other trash, but maybe we also would find treasures. Certainly we will find nothing unless we can develop a good way to couple the transducer to the ground and generate a signal strong enough to reflect back the echo.

Also note that geologists use seismic refraction methods to send a sound to locate bedrock under the ground. This method is not as sophisticated as a doppler ultrasound medical imager. You can read about this at this link: http://thunting.com/geotech/forums/s...ad.php?t=13085

I hope your gall bladder pains are gone soon.
Best wishes,
J_P

[Leto]

mistake I made?

Nice work Leto.
I am affraid you will face huge instabillity on the ground. Air test proves nothing. Especially with unshielded coils!!!???
I would never suggest nobody to even switch ON any detector with unshielded coils. Might confuse you much and give you whole wrong ideas about metal detectors. Further you will have a lot of problems to understand why your detector is not showing neither 30% of perfomances, showed previously on the bench with unshielded coils...
Be sure that once you put shield on your coils and adjust GEB to work without falses, best you can get would be 30-50% of performances you have now.
Once i had dear friend Jackdetect;his main problem was cose he never left workshop and tried his detectors on real field,under real conditions. So his detectors worked fantastic in the air in his workshop, but very bad outdoor,under real conditions! Once i told him that, and he didnt beleived me,actually he was pissed off on me...
For everyone here, i can seriously suggest to go outdoor and fully test detectors on the real ground. Only detector with few or no falses at all IS REAL DETECTOR. Detector with excellent performances in THE AIR and a lot of falses on the ground IS NOT DETECTOR BUT PIECE OF JUNK, totally unuseable in real world.
Now, i am not saying that this Sasho's project is bad. Not at all! I am only saying that your experiencess with it's performances means NOTHING yet.
Until you put shield on coils and go outdoor and adjust GEB to produce NO FALSES at all. Than please come here and report. I am looking forward to see your experiences.
Best regards!

I just wanted to point on mistake he made cose testing coils without shields....

Hi Ivconic,
On contrary these air tests prooved just what I wanted - the shematic works. Do you remember state of mind when you finish PCB from a hand drawn shematic? Were you not eager to find out is it working or not?
No way I would enjoy making shielded coils and waiting for graphite coating to cure overnight just to find out next day that device is not working. As I wrote these coils were made ONLY for testing.

I agree about everything you wrote about unshielded coils and GEB adjustments... I thought these is pretty common knowledge here at Geotech and I'm sorry if I mislead some newcomers. If you read my previous posts you will notice my concern about how well Rebeck type detectors will adjust to ground. No answer from bulgarian guys so I guess we will have to find it out for ourself. But even with unshielded coils I can assert if detector is very sensitive or not, you know that.

FOR ALL This is just the beginning of this thread.. none true search-coils were made, none real depth/stability ground tests were yet performed, again I thought this is obvious.

I do frequently test detectors on ground.. actually I'm even payed doing this on my job. As you know at excavations topsoil is removed, what is left are usually damp clays with wathered minerals and "cultural" layers full of charcoal, brick fragments etc.. Now this soil is much harder to ballance out with GEB circuits than light organic topsoil. So my standards are pretty high in this respect. And yes it is true that TGS is very good MD for heavy mineralized ground.
At least but not last: Hope you will recover soon.

BTW Attached picture (in J_Player style) from last year excavations.. I noticed there is complete lack of women on this technical gizmo forums. Good for us - no distractions. Take a look at my boss in middle - nearly lost his nerves

[aft_72005]

ivconic In addition i would only say that TGS could detect 2cm coin at 70cm distance in the air with unshielded coils. Later when coils were shielded and GEB adjusted to produce no falses at all, same coin can be detected barely at 27cm in the ground and 36cm in the air...
Is this illustrative enough?

Hi ivconic
I t is good result with TGS. Are you built Anker ss60?

[aft_72005]

I am so so... yesterday i was under doppler, examined my liver. Well liver is fine, but i do have 2cm "rolling" stone in my gall-bladder, causing me a lot of pains. Damn. Need to wait for some time and than operate it. I was thinking to totally remove whole gall-bladder, not only stone. Further it will solve all problems. I can drink and eat what ever i want without extra precautions.

I will see...
But i am not telling this without reason;
while lying under doppler i payed attention on it and examined it carefully.
A strange idea occured to my mind; can we make diy doppler and try to use it in prospecting??? Ha?

Hi ivconic
At the first I hope you obtain your health completely .
Don’t worry, one of my friends, remove gall-bladder by surgeon.
He is good life now.
About Doppler: when I was student in university. One of my projects was
Ultrasonic distance measurement or digital ultrasonic meter which capable
Measured maximum 10 meter distance. However I did it with success, but
It was difficult, because when Ultrasonic wave emitted by transmitter sensor,
I had some various reflected pulses from snag in the receiver out put.
For reject fault signals, I forcedly used limited angle Ultrasonic sensors.
Your idea is well, but need working hard. It is new way in metal detecting technology.
Regards.

[ivconic]

"..the problem is to couple the ultrasound to the ground..."

Indeed! This will be the main problem! In hospital, they used sort of gell...
On soil..????
Good point!

[ivconic]

"..On contrary these air tests prooved just what I wanted - the shematic works. Do you remember state of mind when you finish PCB from a hand drawn shematic? Were you not eager to find out is it working or not?.."

Yes, you are right! Extra pleasure is when device works! I agree!

[ivconic]

"..I agree about everything you wrote about unshielded coils and GEB adjustments... I thought these is pretty common knowledge here at Geotech and I'm sorry if I mislead some newcomers. If you read my previous posts you will notice my concern about how well Rebeck type detectors will adjust to ground. No answer from bulgarian guys so I guess we will have to find it out for ourself. But even with unshielded coils I can assert if detector is very sensitive or not, you know that..."

Huh, whenever i see new project i always have fears; sort of prejudice i suppose. For me, main problem are false signals. I keep imagine detector as silent device. Must not produce neither one false. Hard to achieve. And to keep good depth. Also hard to achieve. Even best metal detectors on market,today are not 100% stabile. For example i experienced even DFX and Sovereign producing a lot of falses. If you want to push them to their limits, adjust for best sensitivity and greater depth, you will easy face huge instabillity. On the other hand, if they adjusted to work 100% calm on ground,than they become ordinary machines...not better than any descent handmade.I even experienced TGS works deeper than Sovereign if both adjusted to work stabille,silent, without falses! Maybe hard to beleive but true. From one to another detector i was more and more disapointed, respecting this fact. So finally it evolved in a sort of prejudice in my mind.
Your work is nice.I like pcb.For sure i will make this one according to your pcb, just need some spare time.
In previous post i just wanted to point you on fact that results will getting worse than they are now. Much worse. Like with any other detector.
Applying shields will stabilize device but also "choke" it too. Anyway, it is interesting enough to make it.
Thank you for your effort and pcb! Best regards!

[ivconic]

About Doppler: when I was student in university. One of my projects was
Ultrasonic distance measurement or digital ultrasonic meter which capable
Measured maximum 10 meter distance. However I did it with success, but
It was difficult, because when Ultrasonic wave emitted by transmitter sensor,
I had some various reflected pulses from snag in the receiver out put.
For reject fault signals, I forcedly used limited angle Ultrasonic sensors.
Your idea is well, but need working hard. It is new way in metal detecting technology.
Regards.

It is good idea to start new thread about this. I do not have experiences, i would like to learn more. Simple schematics will do just fine for a start. I surfes arround .net and foun a lot of about dopplers. Most of those were theory. I think TX part will be easy to achieve. More difficult will be "RX" part with signal analysis and visual/audiable indication.
I suggest you to start new thread on this subject.
Regards!