PCB Coil?

[bugwhiskers]

http://members.optusnet.com.au/~hrockey/

Photos of the PCB coils can be viewed here.

[Esteban]

Please, somebody can repair the "noises" of the images (one is a film) with adequate program and post?

[Carl-NC]

The resolution on these images are way too low to be usable.

[Carl-NC]

It has an Inductance of 126uH and a DC Resistance of 25.77 Ohms.

Even if it was done with 2 Ounce copper and Tin Plated, it would Still be about 12 Ohms.

Sandshark PI coils are 358uH and 11 ohms.

[Seeker]

If you solder 1mm diam. wire over the PCB coil ,you will have resistance low then 3 Om.

[chemelec]

If you solder 1mm diam. wire over the PCB coil ,you will have resistance low then 3 Om.

If your going to go to That Extreme, Why not just wind a Radial coil, like I show for My PI Detector.

A Coil of 500 uH and 20 AWG = less than 1 Ohm DC Resistance.

[Esteban]

The real size of the coil is only 6 cm diam. but I increase X 1.5 = 9 cm. Look:

[Qiaozhi]

Try this ->

Download Easy-PC demo from http://www.numberone.com/index.asp
This has a feature that allows the creation of spiral shapes and tracks.
The demo is not time limited, but you cannot save anything. However, there is a way to save the image you have created:

Start Easy-PC.
Select: Add > Add Spiral
Fill in the dialog box to create the spiral.
Tick the "Circular" box.
Select "A" to fit the image to the screen.
Turn off the grid using View > Screen Grid
Select ALT + PrtScr to capture the image.
Paste into a graphics package. I used PaintShop Pro.
Cut and paste the spiral image.
Negate the image. (i.e. black on white)
Save to file.
Here's one I prepared earlier ->

Note - you can easily create an image with higher resolution than the one below, but it's not possible to upload it here due to size restrictions.

[Carl-NC]

Awesome... I own Easy-PC and didn't realize it now does spirals. Was added in V.10. In 15 seconds I created a 30-turn 10-inch coil. Does ovals too.

[Unregistered]

What benefits are there in fabricating such an accurate coil? I'm new to coil making and have been reading this forum a while while self teaching the ins and outs of it. At the same time I also know how to make any size or gauge coil wanted. How would my Minelabs benefit by making a super accurate coil with low impedance? Would there be any noticeable difference in depth?

Thanks...

[Tinkerer]

Spiral coil

Downloaded Easy-PC, made coil design and printed using Output - plotting and Printing. Came out nice but still have to find a way to print a 12 " coil on 2 sheets.

I wonder how much capacitance a PCB coil will have?

Tinkerer

[chemelec]

Came out nice but still have to find a way to print a 12 " coil on 2 sheets.

I wonder how much capacitance a PCB coil will have?

Tinkerer

Make a Smaller Coil, but With Closer Spacing and wider traces, of a size that will Print on a Standard Sheet.
Than Scan it and save it so you can than Increase (Double) its size.
You can than also Split it in Half and prit each half Seperately.

Capacitance is VERY LOW.

[Tinkerer]

PCB coil

Hi Chemelec,

will try that. How does the capacitance of the PCB coil compare with the capacitance of your planar coils? I think the high resistance of the PCB coil could be an advantage for designs that use a resistor in series on the coil to bring the TC down.


Tinkerer

[chemelec]

Hi Chemelec,

will try that. How does the capacitance of the PCB coil compare with the capacitance of your planar coils? I think the high resistance of the PCB coil could be an advantage for designs that use a resistor in series on the coil to bring the TC down. Tinkerer

Because of the Greater Air Space between Wire (Traces) a Equivalant PCB Coil has Lower capacitance and also Lower Inductance for the same number of turns and the same outer diameter. Also a Higher DC Resistance.

If all you want is Higher resistance, you can also make my coils with Smaller wire, But I don't see any advantage. Just more difficult to do.

[bugwhiskers]

Double sided PCB coil

Today I made a double sided 2oz copper PCB coil.

Capsule shaped (straight sides semicircle ends)
50mm (one third) gap between the windings
Length 285mm
Width 150mm
Turns 33
Track width 1.0mm
Track interspacing 0.5mm
DC impedance 6 ohms
Inductance 250uH
Webers (flux) .00081250 (19.5 volts coil energization)

By comparison:
A 400uH wire coil of 1 ohm resistance with 12volts applied would produce 0.0048 webers.

I connected the output of one side to the input of the other side (so the turns go in the same direction) and lo and behold the inductance went up to 900 uH. However, the capacitance went through the roof also making a double sided PCB coil totally useless.

The only way I am going to get anything like .0048 webers is to go larger in coil size with tighter spacing between the tracks (500 uH) and crank the voltage up to 50 volts.