PCB inductor design software?

[Bill Blair]

Anyone know of an on-line source for (preferably free) PCB inductor design software? Failing that, equations for manual calculation? I'd like to experiment with printed circuit board PI detector coils, but haven't been able to find many specifics about them on the web.

[nickf]

Re: PCB inductor design software?

Hi Bill,

I've written a postscript program for PCB coils which I posted last year on Eric Foster's PI forum. Basically you copy it into a text file and save it as something like "coil.ps" then spool it to a postscript printer. Alternatively I can create a PDF version for you and email it to you. I printed a blue toner transfer sheet last year but I didn't have the iron hot enough so the transfer didn't work. I've still got the blank PCB so I'll try it again someday !

Here's the code, you can set the track width, number of turns etc. in the first section. It's currently set for a 30 turn coil 200 mm in diameter.



%! PCB Coil program Nick Fisher 5/7/2002
% default unit for postscript is a point: 1/72 of an inch
% these functions let you use inch and mm for dimensions
% you must add "mm" or "inch" after the number though
% see for example radius definition

/inch { 72 mul } def
/mm { 2.8346 mul } def

% coil specs

/trackwidth 1 def
/turns 30 def
/spacing 2 def
/radius 100 mm def
/centrex radius 22 add def
/centrey radius 22 add def
/centrey1 centrey spacing 2 div add def

% fills to save etching too much copper

0 setgray

0 0 moveto
0 centrey 2 mul lineto
centrex 2 mul centrey 2 mul lineto
centrex 2 mul 0 lineto
closepath
fill

1 setgray
centrex centrey centrex 0 360 arc
fill

0 setgray
centrex centrey radius turns spacing mul 22 add sub 0 360 arc
fill

trackwidth setlinewidth

% pads

centrex centrey radius spacing 2 div add sub trackwidth 0 360 arc
stroke

centrex centrey radius spacing turns 1.5 add mul sub sub trackwidth 0 360 arc
stroke

%the coil

0 1 turns
{
/turn exch def
centrex centrey radius turn spacing mul sub 270 90 arc
centrex centrey1 radius turn 0.5 add spacing mul sub 90 270 arc
}
for
stroke
showpage
% the end

[Bill Blair]

Re: PCB inductor design software?

Thanks, Nick. My HP 5L isn't postscript capable, so I'd greatly appreciate receiving that .pdf file. Do you have any ideas about how to create an effective Faraday shield for a PCB coil?

[Carl]

Re: PCB inductor design software?

There is a freely available program I use for designing planar spiral inductors for chip, called Asitic. However, it assumes chip-sized inductors, on the order of hundreds of microns (micrometers), and cannot handle large inductors.

The program was developed by a grad student at UC-Berkeley, and his thesis probably has all the necessary theory and equations needed to expand it to large PCB inductors. Or, the source code is probably available and might be easily modified.

- Carl