BARACUDA-Legend-1

[Deghbar613]

Are you sure it's EFE? EFE will happen even when you swing the coil through the air, away from the ground. Lift the coil 2m off the ground and spin around in a circle, if there is no noise it is not EFE. You can also use a ceramic magnet to test for EFE.

it's EFE !!!
i tested it using ceramic magnet and outdoor and on the beach
i tested values of Earth field sample pulse delay between 100us to 520us ,
olso delay between 19us to 40us ,what else hmmm
the only thing i didnt did is to try feed integrator 5hz sine wave

[GeoMax]

Hello,

The PI Polones and the TL12000 both have an additional capacitor in the input stage. This might contribute to reducing EFE noise, but I'm not sure. I haven't tested it.
See schematics.


If it helps to reduce EFE noise let us know.

[kt315]

Hello,

The PI Polones and the TL12000 both have an additional capacitor in the input stage. This might contribute to reducing EFE noise, but I'm not sure. I haven't tested it.
See schematics.


If it helps to reduce EFE noise let us know.

Bara does not have the capacitor on preamp input.

[Deghbar613]

Hello,

The PI Polones and the TL12000 both have an additional capacitor in the input stage. This might contribute to reducing EFE noise, but I'm not sure. I haven't tested it.
See schematics.


If it helps to reduce EFE noise let us know.

hi GeoMax
no It doesn't work

[GeoMax]

Is your coil and electronics (enclosure) shielded?

[Carl-NC]

Show us what the waveforms on TP7 and TP8 look like.

[Deghbar613]

Is your coil and electronics (enclosure) shielded?

i have two coils one shielded the other one no , but the same result in both

[Deghbar613]

Show us what the waveforms on TP7 and TP8 look like.

hi carl
this is my TP7,TP8

but i notice something i thing it is the cause of my problems take a look to this pic
coil is 1.5m off the ground and nothing around it

[GeoMax]

Hello,

Could it be that the offset balance is incorrect, or that you're using a counterfeit Chinese NE5534? The NE5534 offset circuit in the posted KT315 schematic definitely doesn't match the NE5534 datasheet. What schematic is your Baracuda PCB based on, and what does your layout look like? I'm asking because someone in another thread also had problems with their design. It wasn't working as expected. The problem was this own custom PCB layout. The PCB tracks, how he routed his design caused disturbances in the electrical circuit.

[Carl-NC]

The preamp output looks good, the sampling pulses look good assuming the pulse widths are matched. That's what R21 is for, to trim the EFE pulse width to match the main sample width. You should adjust this while waving the ceramic magnet until EFE is canceled.

If you cannot get an EFE null by adjusting R21, then here is something else to try: remove C13 and short U4-pin13 to U4-pin11. This will cause both sampling switches to sample at exactly the same time with exactly the same width, and should cause any target -- even a large piece of metal -- to have a very minimal response, or none at all. If you are getting a good response then either U8 is faulty of there is a problem with the components around U6. If you do get a minimal response then R21 is not correctly adjusted or it is not EFE.

[kt315]

Hello,

Could it be that the offset balance is incorrect, or that you're using a counterfeit Chinese NE5534? The NE5534 offset circuit in the posted KT315 schematic definitely doesn't match the NE5534 datasheet. What schematic is your Baracuda PCB based on, and what does your layout look like? I'm asking because someone in another thread also had problems with their design. It wasn't working as expected. The problem was this own custom PCB layout. The PCB tracks, how he routed his design caused disturbances in the electrical circuit.

my board is a copy of original. George's board (GEOTECH) has another reference designators, 'own'.

[GeoMax]

Hi KT315,

do we know what PCB is used by Deghbar613? Yours, the Geotech one or his own?

[Deghbar613]

Hi KT315,

do we know what PCB is used by Deghbar613? Yours, the Geotech one or his own?

this is the PCB i am using

[kt315]

take Quaoshi-George's layout, it's free. this your board is a trash... desolder it.
right trassing is HUGE SCIENCE chapter in electronics, no so you draw like you want doing just trash on finish.
i give you example of WHITE'S COMPANY pcb layout.

[Deghbar613]

The preamp output looks good, the sampling pulses look good assuming the pulse widths are matched. That's what R21 is for, to trim the EFE pulse width to match the main sample width. You should adjust this while waving the ceramic magnet until EFE is canceled.

If you cannot get an EFE null by adjusting R21, then here is something else to try: remove C13 and short U4-pin13 to U4-pin11. This will cause both sampling switches to sample at exactly the same time with exactly the same width, and should cause any target -- even a large piece of metal -- to have a very minimal response, or none at all. If you are getting a good response then either U8 is faulty of there is a problem with the components around U6. If you do get a minimal response then R21 is not correctly adjusted or it is not EFE.

you said : If you are getting a good response then either U8 is faulty
U8? there is no U8