Modifying a Nautilus (or any detector into a 2 box)

[NostalgicMeditations]

Would it be possible to modify a Nautilus IIB or any detector into a two box detector by mounting 2 identical 15in coils to it with the TX of only one coil connected to the detector and the RX to the other? Of course an adapter would have to be made using the handle of a Fisher Gemini to obtain the correct distance to null them. Would this be possible? Would the coils have to mounted perpendicular like the Gemini to work? Reason I am asking is the Nautilus detector has Ground balance and discrimination and adjustable transmit voltage. It would be like having a bigger coil no? It seems that Garrett CTI 2500 does something similar with the bloodhound attachment but the circuitry is probably more advanced than I realize. I do realize that sensitivity to small objects would be lost but 2 boxes are designed to locate caches any way so that isn't an issue. Thanks

[Skippy]

I personally think it's possible, and one of my long-term projects is to make a 2-box conversion for my Fisher F75. This has a non-motion mode with disc ID, which I think would be ideal.

[kt315]

I think chinese MD-5008 (5006, 5012) is good for your project. it works in real static mode.

[Gwil]

From the schematic of the Nautilus IIB it looks to me like it has a response that falls off below about 7Hz (like a lot of motion detectors). That suggests that the coils might have to be moving fairly rapidly to get a target blip sharp enough to be useful. Easy with a search head being swung on the end of a shaft but possibly harder with a 2 box layout. So a non-motion mode would be useful.

On the other hand I haven't tried this mod and I could be talking nonsense.

[NostalgicMeditations]

Thanks kt315 but I have enough detectors already- not interested in another chinese one (already own a Nautilus and a 2 box - needs a handle though and has no ground balance, etc (like a Fisher Gemini).

Thanks Gwil but the Nautilus does have a non-motion mode- just flick the switch and you don't need to swing it. Actually it sort of has 4 modes. Non Motion, Disc, plus Auto Tune on and off. Aside from being able to adjust the disc and ground balance you can also adjust the sensitivity on the disc and All Metal mode. You can also fine tune the coil balance as well. Supposedly the coil voltage goes up to 44 volts. Not sure about a regular 2 box voltage though.

Maybe it will work then in Non motion then? Thanks

[NostalgicMeditations]

I just went up and looked at it. On the box it says Non motion Disc while the other option is motion disc. I can't recall the frequency it operates of off but I thinks its either around 14khz or 18khz. I'd have to look it up. I hear the Discovery TF-900 is widely regarded as the ultimate 2 box. I think it operates at 18kz or somewhere there abouts and 83khz or so. Maybe a modified Nautlius would be even better?


My Gemini look alike (Metrotech 480) operates at 83khz I think and according to the manual only outputs 6.2v at the coil with 100ma? Don't know if its a typo but it puts out 65v and 125ma when it is hook up to a pipe to use the conductive tracing mode. If that is the case my Nautilus puts out way more to the TX coil than the Fisherr Gemini look alike. Problem is the Nautilus has a preamp in the coil and I don't know if it would damage anything with only the RX hooked up on one coil and the TX on the other. I was thinking of using the factory coils because well I have 2 15in (the largest Nautilus made) and I don't feel like winding and fabricating coils at this point yet.

[Davor]

I am about to make my IGSL operate in a 2-box mode, and I already made it respond in "slow motion". It required replacing the electrolytes in feedback to a larger value. I expect it to retain discrimination as well, but perhaps it will need some extra gain at the Rx input.

[Gwil]

Obviously I was looking at the wrong schematic. Can anyone tell me where I can find the right one? Thanks.

[NostalgicMeditations]

Not sure if this is the right schematic but here is another thread I posted earlier that has some schematics and other info on it. Mine is a IIB- IIBA is very close- just has a button to balance the coils. Not sure about the other Nautilus models.

http://www.geotech1.com/forums/showt...coil-for-a-IIB