Help: Coil Housing Dimensions..

[simonbaker]

Next step: cabling and connectors...

I am going to use the following connectors (see below). There are high quality 5 pin audio connectors with gold plated pins. Also two 3.5 mm stereo connectors for the sound-card input and output. I will not use the shown left one (low quality). I haven't found the right cable so I will use three RG174 coax cables which are bound together with tape.

Aziz

I like those connectors a lot, I'm looking for same. Someone suggested S-Video cable, what do you think?

That's good fiberglass stiffens stem -- some day you can find right pipe.

Good work, keep going!

Regards,

-SB

[Aziz]

Damn! I have not much space for the capacitors and some resistors in the coil housing. Well, I will wire this passive electronics part including the balance network not on a PCB. They will be wired compact and in the air and finally glued to the coil housing where some space will be found.

Aziz

[Max]

Next step: cabling and connectors...

I am going to use the following connectors (see below). There are high quality 5 pin audio connectors with gold plated pins. Also two 3.5 mm stereo connectors for the sound-card input and output. I will not use the shown left one (low quality). I haven't found the right cable so I will use three RG174 coax cables which are bound together with tape.

Aziz

Hi,
these are good... I have them too somewhere... but also the low freq connectors used by e.g. ML are good for the purpose in VLF MDs... I usually use that stuff...on my homemades.

Kind regards,
Max

[simonbaker]

Next step: cabling and connectors...

I am going to use the following connectors (see below). There are high quality 5 pin audio connectors with gold plated pins. Also two 3.5 mm stereo connectors for the sound-card input and output. I will not use the shown left one (low quality). I haven't found the right cable so I will use three RG174 coax cables which are bound together with tape.

Aziz

Does anyone know how the shielding is wired for these connectors? Is there a continuous shield on the outside so no wires are ever exposed in the connector?

-SB

[Aziz]

Hi Simonbaker,

Does anyone know how the shielding is wired for these connectors? Is there a continuous shield on the outside so no wires are ever exposed in the connector?

-SB

look to the picture for more detail. There is a connection for shielding and this can be soldered to the shielding of the cable. The whole pins are faraday shielded in the connectors metal housing.

Regards,
Aziz

[Aziz]

Cabling is prepared. The cables are fixed with fibre glas and resin to the search coil housing. There is a flexible 1 cm hot glue added after the tight cable connection. Three 2 m RG174 coax cables are taped together.
This gives a totaly water resistant cabling for underwater or creek search.

Aziz

[simonbaker]

Cabling is prepared. The cables are fixed with fibre glas and resin to the search coil housing. There is a flexible 1 cm hot glue added after the tight cable connection. Three 2 m RG174 coax cables are taped together.
This gives a totaly water resistant cabling for underwater or creek search.

Aziz

Beautiful, in an Alien IV kind of way...

Connector shielding -- thanks, good.

Cheers!

-SB

[Aziz]

Cables and Connectors are done. Now the coils will be assembled in the search coil housing. I will fix first the transmitter coil and glue this. Adding the transmitter resonant tanks with balancing feature will also be done in this part. Last step will be the receiver coil. Quite critical part begins now.

[Aziz]

Transmitter part (TX) of the coil is finished. The balance pot can be accessed via 4 mm hole on the other side. After balancing is finished, the hole will be closed and made water resistant. All the transmitter passive electronics parts (capacitors and resistors) are placed outside the TX coil.
The TX coil is glued very tight to the coil housing.

Next step: fixing receive coil and manual balancing.

Aziz

[simonbaker]

acoustic vibration

Transmitter part (TX) of the coil is finished. The balance pot can be accessed via 4 mm hole on the other side. After balancing is finished, the hole will be closed and made water resistant. All the transmitter passive electronics parts (capacitors and resistors) are placed outside the TX coil.
The TX coil is glued very tight to the coil housing.

Next step: fixing receive coil and manual balancing.

Aziz

Great progress, looking forward to field tests.

Aziz, have you thought about this: accoustic vibrations in coil housing?

Probably not matter for most detectors, but you measure phase so tiny.

What I mean is: TX coil is like electro-magnet. It must vibrate some. Frequency in audio range. Accoustic standing waves in coil housing could amplify vibrations, maybe cause phase jitter. Accoustic properties maybe explain why seemingly identical coils not same.

Just a wild idea...

Cheers,

-SB

[Aziz]

Hi Simonbaker,

Great progress, looking forward to field tests.

Aziz, have you thought about this: accoustic vibrations in coil housing?

Probably not matter for most detectors, but you measure phase so tiny.

What I mean is: TX coil is like electro-magnet. It must vibrate some. Frequency in audio range. Accoustic standing waves in coil housing could amplify vibrations, maybe cause phase jitter. Accoustic properties maybe explain why seemingly identical coils not same.

Just a wild idea...

Cheers,

-SB

this is not a wild idea. This is a good case to study the source for this:
Lorentz Force
http://en.wikipedia.org/wiki/Lorentz_force

The coil windings wants to drift away from each other. This force is direct proportional to the coil current. My coil current is quite low and the coil windings itself are multi-layer stiffed with fibre glass and resin. They have no chance to drift away in my coils. The coils are then glued to the coil housing. Any air in the coil housing will be filled with PU foam. This is a good absorber for such forces. If any force will appear, it will be quite low to measure it.

On PI coils with high coil currents, you can (almost) hear this audio signal (mechanical force).

Well, my coils are quite heavy but they have to fulfill high demands. Therefore they will be quite stable.

Aziz

[Aziz]

I am just balancing my receive coil. It is really difficult to get the optimum position manually. I have glued only one intersection point of the coils. So the fine adjustment can be achieved easier when the glue is dried. Then the second point will be glued and better adjusted. After that, the third point is a good opportunity to correct any residual voltage on the rx coil. Finally, the balance signal from the pot will be soldered.

It's getting interesting. I will be able to go to the field soon.

Aziz

[Aziz]

See picture for clarification.

[Aziz]

%!§uck$%$§uck"§%"§!5

PU foam is not a convenient filler. I have lost my well balanced condition due to tensions of the §ucking PU foam. The coil without bottom plate is quite heavy too.

I have to make a totally different coil: Less size, less weight. Back to the blackboard.

Aziz

[Aziz]

I have found the reason for balance failure of the DD coil:
Air pressure of the PU foam deformed the above RX coil. I can repair the coil by glueing a tight fibre glass bridge on two points. Then the area will be filled again. Nevertheless, the coil is too heavy to work with. But for some tests, it makes sense to repair it.

Aziz