Nautilus revisited

[Melbeta]

you see just two tone. i see advantages: 1/ first try of use preamp in coil. whites, garrett, tesoro, first texas-fisher still do not want use this trick. but only minelab does. i well know this tipo of transistor preamp, plus the emitter follower. thats really superior was for that time 2/ 52V p-p on TX.
in general it is tesoro schematic but with some three 'mods'. want to say every guy with TGSL may moded the schematic to Nautilus but TGSL does not have all-metal part )))
also look DFB post http://www.geotech1.com/forums/showt...2244-Aquasound

Okay, since there is a linking of the Nautilus to the AquaSound detector, I have to tell you that I was told that Jerry Tyndall (Nautilus) was involved with AquaSound in the design of the AquaSound. Now I cannot prove it, but this post by a fellow named Mark, seems to back this fact up. Also keep in mind, that the AquaSound can only be used in white beach sand. It cannot work in Magnetic Black Sand. MELBETA:

Quote:
" The Aquasound is used by the Bulgarian, not built by him. The 20" they are talking about is the depth on a quarter. This is in non-mineralized sand, free of any blacksand. A person just learning the Aquasound would have a difficult time getting 20" deep, because the audio is very weak at those depths. It uses the TR side of the circuit board design that is in the Nautilus DMC 2B. Jerry Tyndall had a lot of input in working out the bugs so it would work to its best potential in saltwater areas of South FL. Its best attribute for hunters in S. FL. was its ability to ignore rusty bottlecaps or other iron type targets. On iron it gives you a drop in the threshold, but because of the automatic retune you get a sort of boing sound when the threshold returns. While any other non-ferrous metal will give you a sharp increase in the threshold, with the loudness of the signal dependant on how deep the target is. A good target sounds similar to a vlf detector being run with a threshold in all metal. I know the builder of the Aquasound, and have seen his log of gold finds found over the years since the development of the Aquasound. Most people would say I am lying if I tried to give a estimate of all the gold and other items he has found. So, I wont bother. If anyone has been hunting back when the TR detectors were the only game in town, they understand why a TR detector is not a very good choice if you are hunting mineralized ground. But in some cases such as S. FL. and other beaches that are non-mineralized a high powered TR detector like the Aquasound can produce some amazeing depths. Comparable to some PI detectors, but you have the ability to not dig iron with the Aquasound. Thought I would throw this out there for anyone who wants to learn a little bit about this detector, without all the conjecture of people that haven't used this detector. Mark"
UnQuote:

[dbanner]

Aquasound and nautilus 2b share exactly the same oscillator circuit.
Here is final version of 2b schematic, have a look at TX oscillator.
All components have now been properly labeled with correct values for 2b.

[Altra]

Aquasound

https://www.youtube.com/watch?v=ENqLPAdXSDw

[Skippy]

A few comments on that circuit:
You have a cap, C with no value on both the 4066 synch detector inputs.
U10 opamp has capacitor 103 for stability...is that correct? The usual value is more like 33pF - 100pF
The output of U9a has a pot of 100K. Is that a preset, and does it have a name, like 'sensitivity' etc?
Q6 has a feedback resistor of 2K7, I assume?
The oscillator has a cap across the TX coil with no value shown.
U8a has a 120K resistor near it, not connected.

[dbanner]

Skippy, thanks for putting your eyes on schematic. Mine are a bit weary at the moment.
Dont know values of caps to input gates of 4066. Could you suggest a value?
U10 cap shown as .01 on DMC2 schematic, so I used this value.
Pot at output of U9 is the second Sensitivity control. This device has two as you pointed out.
Q6 feedback resistor is 2.2M.
Tx oscillator cap is 15nF(14KHZ, 8.4mH coil) but I leave this blank for now.
Also there are no feedback resistors on U7.
I made the corrections.

[dbanner]

Here is the updated pcb trace.

[kt315]

bring this link from russian forum. guy (Alex Serbin) told about aquasound sch in details. http://kamrad-club.ru/-razdel-master...aquasound.html

[Skippy]

The Autotune switch has a resistor near it, with no value.
Is U8 still the LM358 part? You said you changed some of them. Gotta say I don't like the idea of a crappy low-power opamp as the main +10V regulator.
You still have the confusion of the two different +10V supplies. Could the one that powers the -ve voltage generator switches be renamed " +10V_AUX " or something, you choose.
Unused analogue switch U2c should have all 3 pins grounded, I think. The control pin MUST be grounded, I can't see why not all 3 connections.
The TX oscillator has a '100r' resistor, presumably it's 100R ?

I don't know about the synch detector 'C' caps - someone with more TGSL etc experience woild have a better idea.

[kt315]

a link with pics still accessable
http://photo.qip.ru/users/interwert9...346/172025972/

[dbanner]

The schematic reflects EXACTLY what is on PCB. All opamps are correct and are exactly what is on PCB.
100r should be 100R(100 ohms), unused analog switch pins are left floating on actual pcb, but should be grounded I think.
I will re- label the +V supply for negative voltage generator.
The auto tune switch works in conjunction with a pushbutton switch, the resistor value cannot be seen from pics I have but the wiring diagrams will show all switches etc.

[dbanner]

bring this link from russian forum. guy (Alex Serbin) told about aquasound sch in details. http://kamrad-club.ru/-razdel-master...aquasound.html

Very good analytical review. Good info on coils as well.
Can you put pictures of pcb of the device so I can draw trace of layout.

[6666]

Aquasound

https://www.youtube.com/watch?v=ENqLPAdXSDw

Thanks that is interesting

[dbanner]

There's something strange about coil for the 2b that bothers me. I have learnt that concentric coils have what is referred to as a bucking coil. So now anytime I see a concentric coil setup, I immediately think bucking coil.
Yet I cannot see this in pics of 2b coil. What I see are some wires for balancing, but there is only two wires and a center tap coming from tx coil connected to small pcb. The bucking coil is supposed to be part of the tx coil, but I see no other wires connected to tx coil on small pcb.
This puzzles me.

[dbanner]

Can there exist concentric coil without bucking coil.?

[dbanner]

I must read the patent for Nautilus. There has to be a bucking coil.