Garrett AT3

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After abandoning my attempt to do Nautilus clone, at least for now, I decided to take a look at the old Garrett AT3 beach hunter schematic by W.Lhar.

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So I excluded the battery test "beep beep beep" and made a layout according to Mr. L schematic, I used the AT4 Rx preamp instead of the old transformer preamp circuit as the only change.

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I will be posting the layout very soon, maybe someone will be interested as I think this is good device to replicate and improve.
Like the consolidation of all those 8DIL IC's into 16 pin quads for example

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Here is a first look at the unfinished layout which still needs some work obviously.
And also a look at the modified schematic(battery test and pinpoint circuitry excluded and AT4 preamp used instead)
The pin numbers for ic's have been used differently on my layout just for convenience, but they are op-amp for op-amp the same.
This is just a first draft, playing around,for testing a prototype. I would eventually use quad op-amps to do a final design if all goes well.

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The areas in blue are deemed not needed for fundamental part of circuit for testing. The 4016 replaced by fets for switches.
Please any comments or feedback or suggestions would be greatly appreciated.
This circuits interest me because of unique bell tone sound for non-ferrous targets(at least according to manual)

[Tim]

Great old detectors dbanner. Well worth the effort I would suggest. Not sure about replacing 8's with 16's, or 4016. My first choice for a mod would be manual GB, though auto GB may be already enacted by the pinpoint? (unsure).

[SVEN1]

If I recall, the AT series were using the older Groundhog circuit which eventually became the Scorpion.

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Thanks for replies guys.
I don't like all those 8's, surely part of the circuit could be incorporated using few 16's. The phase shifter and power supply(which could be re- designed) and tx an Rx portion could be done with the 8's.
This nice circuit could easily incorporate a digital VDI display add-on, all done with smd components for modern design pcb.
Anyway, the architecture of the circuit is what is most interesting, good for basis of new, more modern design done as self made.
I suspect that there are a few off the shelf coils that would be compatible.