Nokta velox one coil reverse engineering

[Coilbrain]

Dear all,
I am new to the forums i joined in the hope of finding likeminded individuals that love to tinker and modify devices.
My aim here is to produce a bigger coil tuned for deeper larger objects relics cashes and such, attached in the thread are three X-rays of the standard coil that comes with the velox one, this coil operates on 17.kHz frequency.
A bigger aftermarket coil exists for this detector produced by the same manufacturer but is discontinued and very expensive if found i aim to produce an even bigger one for more depth and bypassing smaller objects.
I anyone has worked on self made coils, is an electronics engineer, understands how to gauge coil values and most of all identify the components on this pcb without breaking the resin on the coil i would love to get your take on this endeavour

[pito]

it is a standard DD coil, google DIY DD coil .
https://www.google.com/search?q=diy+...&client=safari

https://www.google.com/search?q=diy+dd+coil%C2%A0&source=lmns&bih=841&biw =1727&client=safari&hl=en&sa=X&ved=2ahUKEwi18cfuhp OEAxU_FFkFHfx7CCIQ0pQJKAB6BAgBEAI

[Carl-NC]

The PCB appears to have 3 components, one looks like a SOT23 package. No idea what they do. Can you measure the coil inductances from the cable connector? That's usually Step 1 in making a compatible coil.

[kt315]

one looks like a SOT23 package

maybe a trimmer.

[Coilbrain]

I have tried getting a reading with a multimeter however it fluctuates and settles at a set number (resistance) also there are 5 pins on the detector end could be one extra unused wire

[Qiaozhi]

I have tried getting a reading with a multimeter however it fluctuates and settles at a set number (resistance) also there are 5 pins on the detector end could be one extra unused wire

You need to use an LCR meter such as this one -> https://www.amazon.co.uk/Capacitance...ps%2C95&sr=8-5

[Smirnov-Arta]

I think it's a balancing board. And "SOT23" is a diode.

[kt315]

no sense to put a diode in a coil. it is a SMD trimmer. in this coil used the balance way from Garrett.

[pito]

there are 5 pins = 2 wire for Tx, 2 wire for Rx and shield wire.
two single wire loops on the center = null tuning loops = green loop on the drawing.

[pito]

fluctuates = capacitor is charging
and settles at a set number (resistance) = low resistance Tx, higher resistance Rx
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Shield wire, not captured on Xray, or could be the single vertical wire on the center.

[Coilbrain]

[Coilbrain]

I highly appreciate your input pito and all members as well I was wondering how can I get accurate readings of set capacitors and coils so I may replicate, also as part of the project I'm trying to make a bigger coil and possibly a better one in the hopes of going deeper even though at the cost of no longer picking up small objects (small objects not my target all areas I wanna work have very deep large objects). furthermore, if I were to produce a larger coil to accomplish set goal can it have same specs as the small one but upscaled or it has to be reworked from scratch ? sorry for all these questions I am not expert at this I am learning here

[Coilbrain]

the smaller coil is the one i have the bigger one is the one I'm trying to replicate or even go bigger for more depth.

[pito]

read this
https://www.geotech1.com/forums/foru...rivers-compare
make your bigger Tx coil and compare with original.

you need to adjust number of turns to have the same frequency or change a capacitor on main PCB. Make 100 turns 0.5 mm wire than unwind until you have original frequency.
to double the range you need increase field strength by 10 times. Double field strength will increase range by few cm.
______________________
small objects not my target all areas I wanna work have very deep large objects = you need a different type machine

[Coilbrain]

read this
https://www.geotech1.com/forums/foru...rivers-compare
make your bigger Tx coil and compare with original.

I am sorry I just now realised that I did not upload the high res pictures this should help