Hybrid Bipolar Detector

[Detectorist#1]

Hi Op04,
You are free to make different experiments. C19 helps to make the coil's current sinusoidal. C19 and 300uH TX coil form LC circuit with resonance frequency as usual. This frequency have to be at least two times higher than working frequency of the detector. For appr. the same coil's current before TX-OFF, the TX pulse have to be two times longer. I'm not sure how effective will be Ground balance in this case (jumper on the place of the C19 capacitor).

[Op04]

Wow...fantastic!! I get your point,, many thanks for this project

[Atallah11]

Thank you

[Carl-NC]

C19 helps to make the coil's current sinusoidal. C19 and 300uH TX coil form LC circuit with resonance frequency as usual. This frequency have to be at least two times higher than working frequency of the detector.

I might help people understand if you post a plot of the TX current and various timing waveforms. Here's one I did for ITMD3:

[algan]

I might help people understand if you post a plot of the TX current and various timing waveforms. Here's one I did for ITMD3:

Hi Carl-, is there a circuit and working code for the timing of the VLF that you provided?

[Carl-NC]

Hi Carl-, is there a circuit and working code for the timing of the VLF that you provided?

No, but it's very similar to what Detectorist#1 is presenting in this thread.

[pechkata]

Hi Carl-, is there a circuit and working code for the timing of the VLF that you provided?

There is but no hex file.

[Detectorist#1]

Some timings of Hybrid Bipolar Detector:

[Carl-NC]

There is but no hex file.

That's a square wave PI, not half-sine. Completely different approach.

[Detectorist#1]

Hi Carl,
I agree with you, the pechkata continues to add spam in some treads.

[pito]

What is showing oscilloscope on D1,D2 ?
What is the advantage of bipolar compared to traditional ?

[Detectorist#1]

Hi pito,
The purpose of D1 and D2 is to prevent the positive input of U1A from appr. 500V peek voltage on TX coil in the moment of the pushing of the button "IRON CHECK".
The bipolar pulses in PI MD eliminates the need of special additional samples for eliminating of the influence of the magnetic field of the Earth. Also, this eliminate the influence of 1/f noise from the first amplifying stage - this gives a possibility to use more cheap OpAmp.

[pechkata]

Hi Carl,
I agree with you, the pechkata continues to add spam in some treads.

Why do you consider it spam?
The approach is the same - from the chip management.
I'm not referring to pumping - I'm giving an idea of management.
I don't believe anyone would do this scheme.

[pito]

I know the purpose of the diodes, I was thinking that decay curve is different than 1 transistor TX.

I have one more question.
I tested one transistor Tx and observed the voltage across the diodes.
The voltages changed for iron , but not for non-ferrous metals like aluminum or copper.
What could be wrong?
Changing the damping resistor doesn't change the circuit's behavior.

[pechkata]

What is showing oscilloscope on D1,D2 ?
What is the advantage of bipolar dosing compared to traditional ?

I don't see the point either.