Nautilus revisited

[Altra]

Could you explain how a narrow sample pulse creates a sharper target response? I can't see it. Thanks.

No, not really. It has to do with the integration time and the slope of the rx signal when the target causes phase shift. There are some early Whites patents that go into wide versus narrow sample times.

http://www.geotech1.com/cgi-bin/pages/common/index.pl?page=metdet&file=patents.dat

On this page under Induction balance check these patents

Wide Pulse Gated Metal Detector With Improved Noise Rejection

Metal Detector With Phase Related Selective Discrimination Circuit

[Gwil]

I'll study them. Thanks.

[Melbeta]

Thanks guys for some good information. I will be starting construction in couple days time beginning with the main pcb.
I have question about search loop balance(SLB). Actually I would like to exclude this feature completely. Does varying the supply voltage of tx oscillator affect the frequency of tx coil, it shouldn't, hence the reason for search loop balance pots. Just a cursory look at pcb seems to suggest the transmit power pot controls Vcc of tx oscillator.
I don't think Mr. Tyndall ever offered double D coil for the DMC. Only concentric.
As for preamp in coil, I'll bring it to the main box, but apart from main pcb just in case I can get an original coil. no worries.

I cannot seem to be able to download KT315 material on the Russians, AOL seems to block it for some reason, so cannot get it. On the LAYout I still do not have any software that will take it from layout into a schematic. You seem to have more material then I have, what I have is the same of what you have I believe.

I do have a drawing of the Search Loop material, and the PCB that went into the actual coil, so am posting those in the forum right now.
Melbeta


And the photo of the Pre-Amp PCB that went inside the coil of the detector...

[Melbeta]

And I do have a bit more info on what is inside the coil itself from postings that another person in the past made. That person took the coil apart and tried to duplicate it. I will have to search for it and see what I have on the inside of the coil.

If anyone can actually send me KT315 Russian material, I have an old dial up modem as I live in a tall Ponderosa forest, so do not see anything except tall pine trees, so my internet access is using AOL on an old telephone line that enters the forest area. If it is in Russian language, I guess forget it as I cannot read and decipher Russian.

And AOL is very controlling over going to Russian websites. I would like to see what KT315 has, and if anyone has an ACTUAL schematic of the DMC 2B model, other then the PCB and the LAY files, I would like a copy.
Melbeta
Found the photo of the inside of the Nautilus coil that used the Pre-Amp PCB. Attached below...

[6666]

I guess forget it as I cannot read and decipher Russian.

To get words off a graphic I use online russian keyboard then paste into google translate, works most of the time but google cannot handle some technical terms.

And AOL is very controlling over going to Russian websites.

Use a VPN

[dbanner]

Lots of info people, thanks.I am drawing a schematic of the 2b, reverse from layout that I traced out from original pcb. It's hard work, will take some time to gather all parts onto single page.
I have everything figured out except for the motion discrim/ ground balance discrim dpdt switch wiring. I can't make heads or tails of it. On photos I have, there is wire going from one of the audio output to this switch, then through the switch and onto a non inverting input of one lm358 via a resistor. To me this makes no sense whatsoever. I think whoever was tinkering with that device got it all wrong!

[dbanner]

As you can see from pics, the purple wire at top of switch goes to top right hand corner of pcb with is one of the headphone outputs. Then when switch is thrown, it connects to opamp input, crazy wiring. I think this is botch job.
The second speaker output goes to headphone jack, which is as it should be.
Maybe I missed something.

[dbanner]

Now I know what I missed, it's the switch marked SLB on/off. Somehow this switch is tied up with audio.
I think I may give up, simply don't have enough info to do complete job of it.

[dbanner]

Mission accomplished! All details of this device have been completed. All is well. Will be posting file with COMPLETE details soon, including component parts list, pcb layout, schematic, wiring diagrams for ALL controls etc.

[Melbeta]

Well, I am 84 years old, and I do not know what a VPN is. I am old school, do not use Facebook or YouTube. The older telephone line does not have sufficient bandwidth to bring in movies inside the telephone line. I have to wait until some day when they replace the old time telephone line with newer telephone line. That is why I am still using AOL. I have no other options as the pine forest scatters the signals in the air. So it is come in to me through the telephone line or forget the internet.

But I would like to know what VPN is. Just in case they replace the old telephone line access to where I live with new telephone line access.

My neighbors are bears, mountain lions, bobcats, deer and other animals.

So if anyone got anything good from those Russian files I would appreciate anyone posting some of those files here and I will download them to my computer that way.
Melbeta

[Melbeta]

Mission accomplished! All details of this device have been completed. All is well. Will be posting file with COMPLETE details soon, including component parts list, pcb layout, schematic, wiring diagrams for ALL controls etc.

There you go! You saw the difference between the two versions. That is what I am after too.
Melbeta

[Qiaozhi]

Well, I am 84 years old, and I do not know what a VPN is.

Here's a good explanation -> https://www.vpnmentor.com/blog/what-...SAAEgJHJfD_BwE

[dbanner]

There is not much difference between the 2 and the 2b. In fact the circuit is the same except for minor changes to accommodate search loop balance(null) feature and some other things.
I'll post everything once I make files look perfect and professional. You will be pleased.
Actually, this device is rather easy to construct once you have proper data and all the parts, especially those multi-turn pots. What I like is that there are no trimmers on pcb, only 1% precision resistors.

[dbanner]

Members, thanks for pic of coil, I did not have this one. Can you make out what is written on inside of coil? Also, thanks for posting null circuit, it matches the one I reversed draw from pics.

[6666]

Well, I am 84 years old, and I do not know what a VPN is. I am old school, do not use Facebook or YouTube. The older telephone line does not have sufficient bandwidth to bring in movies inside the telephone line. I have to wait until some day when they replace the old time telephone line with newer telephone line. That is why I am still using AOL. I have no other options as the pine forest scatters the signals in the air. So it is come in to me through the telephone line or forget the internet.

But I would like to know what VPN is. Just in case they replace the old telephone line access to where I live with new telephone line access.

My neighbors are bears, mountain lions, bobcats, deer and other animals.

So if anyone got anything good from those Russian files I would appreciate anyone posting some of those files here and I will download them to my computer that way.
Melbeta

Seeing that your friends are bears try TunnelBear, you can get free daily data its what I use .

TunnelBear is a public virtual private network service based in Toronto, Canada. The company was founded by Daniel Kaldor and Ryan Dochuk

https://www.tunnelbear.com/