Concentric Coil Design

[Gary]

Does this look about how it should.

This is my first attempt at a Concentric coil. Supplying a 10 Volt, 100 Khz sine wave in, it appears to cancel perfectly on the scope.

Take care.......Gary

[Dave Emery]

Re: Concentric Coil Design

Gary,

I tried to email you but your address bounced. Please send me your address to: [email protected] Dave. * * *

[sevzirfo]

Concentric Coil + ferrite transformer




Hi!
It is my variant Concentric Coil with the agreeing ferrite transformer for VLF detectors.
Feature - ferrite transformer adjustment Coil
I yet did not test Coil to the detector. With use of the external generator of signals 8 kHz Coil is adjusted well.
Adjustment of suppression of a signal - selection of coils of the transformer

sevzirfo

[Beachcomber]

Re: Concentric Coil + ferrite transformer

That's an interesting way of getting around having to make a bucking coil!! Very interesting!!! I wonder why the coil manufacturers haven't thought of that. It sure could make tuning a lot easier. Thanks for posting your idea!!!

HH

Beachcomber

[Chris]

Re: Concentric Coil + ferrite transformer




Hi Sevzirfo

very interesting....I add to your diagram some additional construction information like start and end of the coil winding direction. Does it match to your test arrangement? What kind of ferrite transformer you use (N=1:1)?

Regards
Chris

[proscan]

Re: Concentric Coil + ferrite transformer




This method of nullig used to be used in american PSS-11 mine detectors (70's).

It worked as an auxiliary nulling system as the search head had 4 receive coils that worked in nearly balanced configuration.

proscan

[Beachcomber]

Re: Concentric Coil + ferrite transformer

If this method works well and if they knew about it back in the '70's why do they still use the bucking coil arrangement in concentric coils instead of this method? It seems that it would be much easier to build physically and much easier to tune electrically than the bucking coil method. I would think that there must be some drawback to this method or the detector manufacturers would have adopted this method for making thier own coils. Does anyone know the answer?

Thanks

HH

Beachcomber

[Rudolf]

Re: Concentric Coil + ferrite transformer

The answer is quite obvious - you can't get your coil's best with such transformer unless you use very precise technology.
Loop tuning is MUCH simpler

[sevzirfo]

ferrite transformer - In detail




Hi!

The circuit- OK!

I tested 2 ferrite rings by a diameter 25 and 45 mm of the unknown mark.
Number of coils of the transformer
1 winding - 18 coils
2 windings - 9 coils
Wire by a diameter of 1 mm - some wires in plastic isolation.
I think, that the diameter and mark of a wire of the large meaning(importance) has no
From a beginning L1 and L2 are adjusted in a resonance on working frequency with the help Ñ1 and Ñ2, following
Adjustment of suppression of a signal make by change of number of coils of 1 winding

sevzirfo

[kt315]

Re: Concentric Coil + ferrite transformer

what would be if we will take the ferrite pot with brass tuning core. what may be simplest in the way?

KT315.