Vlf metal detector problem

[ArchibaldSTM]

Can you give an example circuit to amplify the RX signal?

Is it difficult to find it yourself... religion does not allow it? Especially since you were told which models to look at.

[Carl-NC]

A simple non-inverting opamp with a gain of 100 would be a good start.

[sifirzeri]

Can you give an example circuit to amplify the RX signal?

[sifirzeri]

Thank you admin

[Carl-NC]

It is very difficult to see a target signal just looking at the raw RX coil voltage. You will need a amplifier. I suggest you look at a Tesoro schematic like the TGSL or Bandido. Do a forum search for those.

[sifirzeri]

Yes, I measure my TX signal. When I put the coils on top of each other, I see the TX signal in the RX coil. Then, when I put the coils in the middle, I reset the oscillation. I start testing, but when I approach a metal object, the RX does not oscillate. Is there a circuit to amplify the RX signal?

[Carl-NC]

No and no. Maybe show us your circuit diagram and coil design. Are you able to measure the TX signal, and is the RX signal (no target) near zero?

[sifirzeri]

I'm trying to increase the rx signal TL072 but it doesn't work. Is it necessary to rectify the rx signal? Do I need to wrap the coils in aluminum foil?

[Carl-NC]

A metal target will not normally change the TX signal in any noticeable way. With an IB coil the RX signal should be nearly zero and a large metal target will make a noticeable RX signal at the preamp. To see smaller targets, you need to look at the demod signals.

[sifirzeri]

Hi , I'm trying to make a vlf metal detector. I see the 8khz signal I produce in the tx and rx coils, the coils are in proper alignment. I reset the oscillation, but the oscillation does not move in metal detection. Where am I making a mistake? When I bring the RX coil closer to the TX, I turn on the LED. Frequency transmission also occurs. No detection on metal.