Aquasound

[dbanner]

If an owner of a dmc2bA could be persuaded to take some pics of the daughter board contained in the chassis box, then the circuit schematic could be had.

Melbeta, nice to see you're still above ground. When people like yourself don't report in from time to time, well, you know what I mean.

[Melbeta]

Semtech used what I believe was a figure 8 coil, to decide if the target was positive or negative, all you had to do was see if the target was under the positive hole or the negative hole. Now I think dual TID meters for each hole would be superior for target guessing... Melbeta

[dbanner]

The Nautilus and Aquasound are essentially the same coil, TX and Rx front end.
I always thought that if Jerry's auto balance circuit from the dmc2bA is added to the aquasound, then you would have a great metal detector for the white sand beaches and seas. Problem here is that nobody has a schematic for the circuit.

Fiddling with those feedback pots in order to set up the detector is bound to turn off but the few hard core hunters.

[Altair]

Interesting story. I don't know how things are gone but for sure there is a sort of intriguing aura about this detector. I was working about state of the art protopype when Aquasound pass under my eye and catch me with him. Advance tecnique project I am working on can wait, now I want to do a try to this dinosaur schematic and see what happen with it!

[Melbeta]

Let me make a educated guess. There was an engineer, working at Whites Electronics, back when George Payne made the Whites Supreme V model, the one in 1975, which did not have the discrimination circuit in it, which came out in 1976. It also used the older Whites coil. Now this engineer looked it over, and as he had the ORIGINAL schematics at Whites, he decided to remove the VLF, and make it a TR machine, and took it to the white sands beach of Florida. Then he kicked into extra voltage obtained in some neat way. And viola it goes 18" to 20" deep, and since there is no black sands, it finds every doggone thing... Let me go further. Later on, Whites would come out with a new coil. Then they did some changes in the circuit, to bring in the new coil. Now when other people sent in their detectors, to update them, as Ken White liked to do, more changes were made. So the Supreme V was far from the 1975 model...Then Jerry looked at it, and decided to make his Nautilus similiar, but not exactly the same kind of detector as the Supreme V. You know, engineers have said and said other times, that a detector will go deeper without the VLF, IF there is NO BLACK SANDS to content with.
Melbeta

[dom44]

i have found that the feedback resistor R4 or capacitor C5 value needs to be changed the moment i dropped the value of the resistor i got stable oscillation, still playing with it at this point.

[Altair]

I just did an experiment with a transmitter coil I used 20 turns 5 turns center tap 5 turns 20 turns and got about 90 volts sign wave on the scope but unstable the moment you connect the earth stops oscillating still playing with it but interesting results definitely has a transformer action on the coil. i was using the 5 turn wingdings and center tap but have to play with the resonant capacitor was oscillating at about 49khz to high.

dom44,
oscillation must be stable. Check the direction of coil connections, you must have the situation described at my post #54.

[dom44]

I just did an experiment with a transmitter coil I used 20 turns 5 turns center tap 5 turns 20 turns and got about 90 volts sign wave on the scope but unstable the moment you connect the earth stops oscillating still playing with it but interesting results definitely has a transformer action on the coil. i was using the 5 turn wingdings and center tap but have to play with the resonant capacitor was oscillating at about 49khz to high.

[dom44]

thank you Altair

[Altair]

I was wondering Altair do you have your last Kicad schematic you posted in another format such as PDF i can't get Kicad to work on my computer at all thanks

Here the last revision I made:

[dom44]

I was wondering Altair do you have your last Kicad schematic you posted in another format such as PDF i can't get Kicad to work on my computer at all thanks

[Altair]

hows is this for size very compact 75mm x 57mm haven't checked it yet and not built yet


[ATTACH]50307[/ATTACH]

dom44,
it's look well, great work!
I am busy with some minor modification to the original design in order to suite my requirements. Keep in touch!

[dom44]

hows is this for size very compact 75mm x 57mm haven't checked it yet and not built yet

[jasonNZ]

Thanks Altair

[Altair]

was looking over the schematic and the picture of the board, i would imagine some of the components have been updated ?

This looks like a Polystyrene cap thats polarised , in the schematic has it been substituted with a film cap ?
[ATTACH]50270[/ATTACH]

then noticed the cap the seems to be between resistor 48 and 56 ?
[ATTACH]50271[/ATTACH]

and then cap 19 seems to be extra compared to what was on the board ?

jasonNZ,
the cap at your image: Screen Shot 2020-05-16 at 8.10.17 PM.png is not polarized; it's a Polystyrene one but, for the circuit that is, I believe it could be replaced with polyester one.
The cap at your image: Screen Shot 2020-05-16 at 8.09.45 PM.jpg should only modify the envelope of sound signal; it is not important for me and it not part of original schematic infact it was added later on PCB.
Important are the 30pf, 100pf and 470pf capacitors that should be silver mica or similar.