PCB mono coil

[Qiaozhi]

Thanks,
Spiral is nicer, if Easy PC does a spiral, then I might have to use that.

If I change to spiral, it shouldn't change the specs, maybe make it a bit better (symmetrical)

How is the performance of this ?
Do you sell your printed coils ?

I only did this as an example with Easy-PC in case you wanted to use a spiral instead. This does not exist as a real PCB coil. It's roughly the same specification as your own coil, with the same inner and outer diameters and number of turns. If you want something different, I can easily make a different spiral and post the Gerber and/or PDF file here.

[Aziz]

20 cm - 30 cm diameter, 1.4 mm wire thickness, 28 turns
PDF and PS file
Page size 35 cm x 35 cm, 2400 dpi

Aziz

[Aziz]

Hi guys,

if someone needs other PCB mono coils, just specify the following parameters and you will get the perfect spiral coil layout:
- inner diameter [cm] (<- that's the only unit I accept!!!)
- outer diameter [cm]
- number of turns
- track width (wire thickness) [mm]
- page size (PDF & postscript file) [cm]
- dpi resolution
- printing coil info (yes/no)

Other file format's besides the PDF & PS aren't supported.
Cheers,
Aziz

[ApBerg]

1. make spiral in Sprint Layout 5
2. save as bmp
3. import in Paint
4. canche format 100/50 ratio
result: see png

[Davor]

just specify the following parameters and you will get the perfect spiral coil layout

Is it possible to get a square spiral coil as well? I'd be mostly interested in oblong form at standard Eurocard format 100mm X 220mm with maximum copper to clear ratio. I think mitering will not make any difference. Knowing the expected inductance will be a bonus.

A day before yesterday i had a thorough tactile view of Tesla's sculpture made by Meštrović He might have been a virgin till death, but he knew his stuff.

[WM6]

1. make spiral in Sprint Layout 5
2. save as bmp
3. import in Paint
4. canche format 100/50 ratio
result: see png

Nice idea ApBerg, thanks.

Probably Aziz can do this (ellipse) without resizing line thickness?

[Davor]

Please note that copper lines are not the same width here. As the spiral is squashed into oval, so are the copper traces

[Aziz]

Hi guys,

yes, I can make elliptical & rectangular coils as well.
Just specify it exactly!!! Otherwise, I'll respond with "Syntax (T)Error!"

Aziz

[Tepco]

Inductance = 310 uH (using oscillations when in parallel with 1uF capacitor)
Resistance = 4.7 ohms
Capacitance to shield 2.5nF

This is the problem. Some time ago, i spent some time, and money too, messing with PCB made coils.

With this particular coil, excessive resistance is problematic, ramping up required peak current across 4.7R coil (+cable resistance) is not the best idea, less field, energy wasted on resistive losses. If you use double sided PCB, connect both sides (coil shaped) in parallel and add shield externally, even then resistance will be excessive, not even silver or gold plating can save it.

This “camouflage paint” shield is very original, but problematic, again, too much metal in search head. Probably responsible for 20uS decay, you probably wont be able to lower it much adjusting Rdump

BTW. 2,5nF capacitance is wrong value and way too high, check or measure using different method\instrument, 1\10 of that or less is more realistic value.

20\30cm is nice ratio for 30cm coil, optimum seems to be 1:2 but not feasible for large coils, inductance will be excessive.

Susceptibility to false responses due to mechanical deformation of PCB is normal, you still need casing and epoxy to make it mechanically sound.

Then compare cost of this to 3$ needed for wire, some epoxy and some (very small amount) of time needed to build it using different method, you will see why i’m not too enthusiastic about PCB flat spiral coils.

[Qiaozhi]

Is it possible to get a square spiral coil as well? I'd be mostly interested in oblong form at standard Eurocard format 100mm X 220mm with maximum copper to clear ratio. I think mitering will not make any difference. Knowing the expected inductance will be a bonus.

Try this ->
You can view the Gerber files using Gerbv in Ubuntu Linux.
If you're using Windoze, there are some free Gerber viewers available, such as "DFM Now!".

[Davor]

Nice

[Altra]

I was making some pcb's on my cnc router today. So I decided
to try a quick pcb coil.

It is 4" x 6" has 30 turns and the traces are about 7mils

Results in 122uH @ 7.6ohm

It appears this is more suited to larger coils which require less turns for usable inductances. Or stack boards to get more inductance. It would be neat to do OO coil with an overlapping windings one on top, one on bottom.

Does anyone know how to do spirals diptrace?

Here's some photos

[Davor]

I think Aziz can cross check both versions and compare results. Beside maybe a somewhat better WAF a spiral will most probably have no advantage at all. This seem to be a perfect example of well used tools and materials.

[Tec]

Yes,
The resistance is quite low because it is 2oz copper instead of the standard 1 Oz.
The manufacturer can do anything I specify, resistance can be lower still.

The shielding doesn't support eddy currents, only within the width of each finger.. can make the fingers smaller if necessary.
Yes, the capacitance measurement to shield is wrong (just done with a multi meter).

I think at this stage, Coils wound with wire are cheaper and better.
Because shielding can be above and below (Wrapped around)
The coil needs to be as rigid possible
and there needs to be a spacer between the coil and outside world to stop things getting too close.
I have made another coil with a rubber hose as a former, I will try it out and let you know.

This is the problem. Some time ago, i spent some time, and money too, messing with PCB made coils.

With this particular coil, excessive resistance is problematic, ramping up required peak current across 4.7R coil (+cable resistance) is not the best idea, less field, energy wasted on resistive losses. If you use double sided PCB, connect both sides (coil shaped) in parallel and add shield externally, even then resistance will be excessive, not even silver or gold plating can save it.

This “camouflage paint” shield is very original, but problematic, again, too much metal in search head. Probably responsible for 20uS decay, you probably wont be able to lower it much adjusting Rdump

BTW. 2,5nF capacitance is wrong value and way too high, check or measure using different method\instrument, 1\10 of that or less is more realistic value.

20\30cm is nice ratio for 30cm coil, optimum seems to be 1:2 but not feasible for large coils, inductance will be excessive.

Susceptibility to false responses due to mechanical deformation of PCB is normal, you still need casing and epoxy to make it mechanically sound.

Then compare cost of this to 3$ needed for wire, some epoxy and some (very small amount) of time needed to build it using different method, you will see why i’m not too enthusiastic about PCB flat spiral coils.

[Tec]

CNC

Altra,
That CNC router is awesome,
I wish I had one.

I use Diptrace by the way, I didn't know how to use spirals so I did the circles.

I do think my PCB the coil is very 'clean' sounding and sensitive on targets.
It is 2 Oz copper, so half the resistance of 1 Oz (or maybe not half, but less,.. whatever the formulas say).