Substituting a DD with coplanar?

[Mullihaka]

I have built a VLF detector according to the article in Elektor nov 81 issue. It should have a factory made DD coil.

Would it be possible to substitute that with a coplanar coil, if I just get the inductance right for the resonance frequency in the detector?

Can any DD coil in any IB detector be subsituted with a coplanar one?

[Max]

I have built a VLF detector according to the article in Elektor nov 81 issue. It should have a factory made DD coil.

Would it be possible to substitute that with a coplanar coil, if I just get the inductance right for the resonance frequency in the detector?

Can any DD coil in any IB detector be subsituted with a coplanar one?

Hi,

1. it's a very complex project, I remember I read it all from start and it's not trivial: if you made PCB and works good I think you can make the coils you need too.

2. the factory made coil is the one in about square shaped container, but I don't know about e.g. inductances of it, I didn't build it. Just read.

3. you can make CC "equivalents" for any VLF coil, if suite transmitter and receiver requirements. On tx you need to match expecially operating frequency, so inductance required to get that frequency; sometimes Q issue is another requirement for good operations. On receiver you must suite required nulling and phase in absence of target.
If you suite that requirements your CC will work on MD whatever it was original coil for it.
Usually, making CC is very complex issue... cause you have dependencies between TX and RX coils , more than with other designs like DD. You could also experience lowered sens, as well as increased sens in CC depending of how good you design and made the coil. On DD it's easy make experiments cause you simply need sliding the coils to suit nulling and phase requirements most of the times: in CC is tricky and unreliable process... be prepared to waste lot work, wire and nervs cause of that.
Making good CC for PI is about trivial stuff ; if you read Dave Emery's article... that covers VLFs CC you'll see it easy, but, when on real coils/MD the principle explained is just a starting point... and more complex issues arising then to complicate your life.

I warned you... it's always "possible" make a good CC and use it instead of DD, but do at your own risk!

Kind regards,
Max