Detection problem

[Hach]

I agree.
65mm Radius of 100 turns is about 2.8 mH. This detector needs about 300uH coil (Note: m = milli or 10e-3 & u = micro or 10e-6)

There is a good coil calculator at the top of the COIL sub-forum.

What about this calculator for basket coil
Any ideas
http://www.472khz.org/pages/tools/co...erweb-coil.php

[waltr]

What about this calculator for basket coil
Any ideas
http://www.472khz.org/pages/tools/co...erweb-coil.php

This calculator does calculate inductance so usable.

I haven't built coils of that configuration so unknown how well it works but probably good enough.

The GeoTech calculator is good as I have used it and then measured coil build with very good match of calculated verse measured inductance.

[green]

Reply #7(thread below) has some coils I've made. Don't know how close the calculators(link below) match the coils.

https://www.geotech1.com/forums/show...462#post257462

[godigit1]

I have a older version of this board but all I have left of the supplied Cd is the schematic. So I have lost the set up procedures. But I remember you have to zero r11 via r10. If you haven't done that allredy.


I actually recently powered it back up to set up for a nephew. Just threw a coil on havent even adjusted damping yet. Still works after sitting three years.

[green]

Reply #7(thread below) has some coils I've made. Don't know how close the calculators(link below) match the coils.

https://www.geotech1.com/forums/show...462#post257462

Tried calculators above and reply #31 for coil A. All three calculate 246uH, I measured 273uH. Maybe a measurement error?

[Davor]

Most probably you simply packed the coil very tightly, and it resulted in higher inductance.

[waltr]

Or missed the correct wire diameter in the calculations.

The GeoTech calculator requires the Outer diameter is the insulation. This allows calculation of the spacing of each wire within the bundle. Once I got this correct calculated and measured inductance became very close, <2%.
You have an error of 10% which is still pretty close.

[kt315]

transistor tester is good measuring L. low price kit. just wind MORE windings and measure.
we told about in especially made chinese toys thread.
also we had run to resolution there is not good calculate soft for the basket coil.
https://www.aliexpress.com/item/3281...8-c9f37a067afa