Famous Trails MD 7012 Larger Coil Project

OK
I'm now convinced, after spending over 50hrs with this thing, I think it has great features and depth potential for a $15 investment.(plus parts and labor)
After seeing dozens of machines work on YT, I'm convinced this thing can compete, aside from disc ability.
NOTE: The MD 7012 and 3006 are exactly the same. (except for the #)

My plan is to make a scale up copy of the original coils and to separate the box from the pole.
My big Q is, if I scale it up and keep the resistance matched, will the circuit see it as the same?

Is there anyone else who has had one of these units and did any mods?(comments?)
Is anyone familiar with the coil configuration?
See pics: famous trails model 3006 - cant zero out unit just tones.
I haven't seen another design like it in any other detector and I think it's a good one.
Thanks in advance for all the great tech advice I will soon be getting...right?  :



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Thanks much for the input GD!
So, would it be common practice to reduce the wire gauge or # of turns in a scale up project?
I'm a self taught audio electronics tech, but little understanding of different detector/inductance circuits.
Is there a simple formula if I knew the # of turns, wire dia., coil dia. to match things up on a larger scale?
I threw together a larger dual coil copy out of some wire that I had on hand for decades but it was fatter wire so I just used all 100' and still didn't come up with enough ohms so I added a resistor and matched it up that way.
The Xmitter coil is closer and is also off but I was able to tune it and got it to detect at about 1".
Maybe just a general rule of thumb would do for inductance coil scale up projects?
Also, how much does stacking/layering come into play when speaking of inductance in coils?
I would think that the more organized the coil is, the more precise the field will be?
Any general tips for making scale up coils in a unit of this type? (I assume you already know this is a dual coil transmitter type)
I do have an O-scope, audio freq gen and counter.

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		Quote:			Posted by HECTOR
	Thanks much for the input GD! So, would it be common practice to reduce the wire gauge or # of turns in a scale up project?

You're welcome. There is a practical limit regarding the scaling up of a coil on an existing machine. The ones you see on TV chasing meteorites are not just bigger coils attached to a detector even though they look like it. The power must be amplified and sometimes a separate tuning circuit is in play to step the frequency up or down.

If you really want a big coil detector, start with the coil and design a detector to use it. Seriously.

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		Quote:			Posted by HECTOR
	Your logic escapes me since many detectors offer several sizes of coils. Undecided There must be something that you left out. Huh? For this particular machine, are you saying that it's impractical to try and gain more depth by stepping up the coil size a bit?

A bit? No problem. Yes, there are a variety of coils for many machines which are all matched in impedance to the machine making them interchangeable. What I said is that there is a PRACTICAL LIMIT to how large you can go before you need to amplify and alter the signal to drive the larger coil.

It's not a simple project, my friend.

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