Twin Loop Tr Seeker Highly modified

[der_fisherman]

Here is the Twin Loop treasure Seeker modified with optocouplers to separate the power supplies and a second opto to separate the speaker circuitry, and one Bipolar transistor which drives the coil is removed, and other transistor is replaced by FET IRF840...

Original pcb tracks are intact for adding the dual coils both in recieving mode, a third Tx coil is large (1.5 foot dia) which contains these 2 Rx coils (7inch in dia) dia, turns etc depends on the damping resistors used and experimentation.

Hi,

That is only a PCB, simply not enough to go with the changes you mention. Is there somewhere on Geotech where the full information is easier to come by?

Thanks anyway......

[6666]

Fisherman here is the original twin loop article
the pcb had a few errors.

http://www.geotech1.com/cgi-bin/page...loop/index.dat

[der_fisherman]

TwinLopp changes

Dear 6666,

you may have forgotten, I mentioned before that I actually built the original and had a lot of fun with it and still have it.....it was mostly mentioned with regard to the use of a router to make the search coil.....

Also I still have the ORIGINAL ETI MAGAZINE (somewhere!) with the article in it....I also have it on .pdf for "insurance".....

But thanks anyway.

The reasons behind my request was that Sharky was talking about deep and fundamental "improvements". It is these improvements that I was asking for the full details....so he has kindly sent me (us all!) the changed PCB and the modified schematic.

Looks good and now makes far more sense.....

But thanks anyway and have a great day.....

regards

Andy

[Qiaozhi]

The reasons behind my request was that Sharky was talking about deep and fundamental "improvements". It is these improvements that I was asking for the full details....so he has kindly sent me (us all!) the changed PCB and the modified schematic.

Looks good and now makes far more sense.....

Are you going to post the details here?

[der_fisherman]

They are already here, you haven't been paying full attention.

Look for Sharky's recent posts in this blog......

Regards

Andy

[Qiaozhi]

They are already here, you haven't been paying full attention.

Look for Sharky's recent posts in this blog......

Regards

Andy

By "recent", I presume you mean Sharky's posts dated 2007 ... as there is nothing more recent than that.

I asked the question because you clearly stated in your post: "so he has kindly sent me", which I took to mean that Sharky had supplied you with more up-to-date information.
Apparently this is not the case.

By the way, this is not a "blog". It is a "forum".

[der_fisherman]

Twinloop

By "recent", I presume you mean Sharky's posts dated 2007 ... as there is nothing more recent than that.

I asked the question because you clearly stated in your post: "so he has kindly sent me", which I took to mean that Sharky had supplied you with more up-to-date information.
Apparently this is not the case.

By the way, this is not a "blog". It is a "forum".

I did not look at dates. That was my failure. I have not received any direct posts from Sharky, apologies if I gave the wrong impression.

My English, after 30 years in Germany, gets a bit convoluted.....

I actually see the Forum as being the WHOLE website, a blog being a single theme on that Forum. That is as far as I am aware, the current definition for such things. This allows us to define easily one from the other.

Regards

Andy

[Qiaozhi]

I actually see the Forum as being the WHOLE website, a blog being a single theme on that Forum. That is as far as I am aware, the current definition for such things. This allows us to define easily one from the other.

Regards

Andy

A blog is a usually created by an individual who makes regular entries about particular events (usually relevant to themselves) and often contain photos and videos. It is analogous to an on-line diary.

A forum is for on-line discussion between many different people. The Geotech forums are such an example. The forums are a part of the overall Geotech website.

[der_fisherman]

A blog is a usually created by an individual who makes regular entries about particular events (usually relevant to themselves) and often contain photos and videos. It is analogous to an on-line diary.

A forum is for on-line discussion between many different people. The Geotech forums are such an example. The forums are a part of the overall Geotech website.

Each to his own idea!!

[ZOUjiarui]

TwinLoop detects can 180cm

TwinLoop detects coke can at 180cm in air, and a 1 cent at 55 cms, there are some modifications the opto will be 4N25 with a 270ohm(should be less than 400ohms at the transistor side to make the IC to be more than 50mA for fast turn on.), audio stage opto can be 4n35.

Modifications at preamp is Ne5534, and care has to be taken as both opamps are inverting along with TL081, and the next stage is an pnp transistor so re design has to be made to get a noninverting signal, if one of the opamp is configured as noninverting change the transistor to NPN as its base should be getting a positive voltage.

My Coil dia is 14inch and greater, Tx dia 0.5mm guage 30 turns, 0.1 to 0.2mm guage Rx 100 turns or greater, try different winding mechanisms for different results like spiral, buck coil etc etc....

Sharky are you still following the forum? Any progress on the project?

[ZOUjiarui]

Didn't notice, it's been 13 years since Shark was last active, and he's unlikely to have any new replies. Anyone verified his modification?

[ZOUjiarui]

Can any available information be provided? Thank you so much

[GeoMax]

Hi,

I had a quick look at the circuit modifications. The added potentiometers are good for fine tuning the unit, no doubt. The two added opto coupler I think have no benefit. The NE5534 in the front-end receiver is a better option than the 709. These modifictaions are in total okay. But the secreate is in the search coil. With a good search coil any detector goes deeper.