Question about DD coil

[gallico58]

hello everyone I would like to ask a question, in a VLF DD coil you need the shielding of the TX part, ok I understand you need the RX part but is it necessary in the transmitting part?

[gallico58]

hello everyone I would like to ask a question, in a VLF DD coil you need the shielding of the TX part, ok I understand you need the RX part but is it necessary in the transmitting part?

please who can answer me?

[waltr]

Not really sure but I will take a guess.

Since the TX and RX coils are coupled, think transformer, then noise or static onto the TX coil will couple into the RX coil.
Thus concluding that both coil need shielding.

[Carl-NC]

It depends. If the TX coil is part of a free-running oscillator then ground capacitance can cause frequency pulling which might affect the operation. It's not much, and if the demods clocks are derived from the TX signal then probably there's no real effect. If the TX coil is driven then ground capacitance can affect distortion which could alter demod timing. Again, the effect will be slight so you may be able to get away with it. But if you are going to shield the RX coil then I don't see any benefit from leaving the TX coil unshielded.

[ZOUjiarui]

Hi, everyone, I want to ask a question. Is there a VLF metal detector that uses a single coil? Does it have a corresponding patent? Part of the coil passes through the transformer, and the other parts are completely unchanged.

[Qiaozhi]

Hi, everyone, I want to ask a question. Is there a VLF metal detector that uses a single coil? Does it have a corresponding patent? Part of the coil passes through the transformer, and the other parts are completely unchanged.

Have a look at this thread -> Minelab Go-Find

[ZOUjiarui]

Hey, Qiao Zhi, I saw it.

[ZOUjiarui]

[ZOUjiarui]

Its owner modified a single-coil machine and sent a video of its work. I think it is very difficult, and it may be a false thing.