diff options
| -rw-r--r-- | twisted_coil_gen.py | 33 |
1 files changed, 24 insertions, 9 deletions
diff --git a/twisted_coil_gen.py b/twisted_coil_gen.py index 218c020..253f173 100644 --- a/twisted_coil_gen.py +++ b/twisted_coil_gen.py @@ -6,6 +6,7 @@ import os from math import * from pathlib import Path from itertools import cycle +from scipy.constants import mu_0 from gerbonara.cad.kicad import pcb as kicad_pcb from gerbonara.cad.kicad import footprints as kicad_fp @@ -89,8 +90,8 @@ def svg_file(fn, stuff, vbw, vbh, vbx=0, vby=0): @click.option('--footprint-name', help="Name for the generated footprint. Default: Output file name sans extension.") @click.option('--target-layer', default='F.Cu', help="Target KiCad layer for the generated footprint. Default: F.Cu.") @click.option('--jumper-layer', default='B.Cu', help="KiCad layer for jumper connections. Default: B.Cu.") -@click.option('--windings', type=int, default=5, help='Number of windings to generate') -@click.option('--diameter', type=float, default=50, help='Outer diameter') +@click.option('--turns', type=int, default=5, help='Number of turns') +@click.option('--diameter', type=float, default=50, help='Outer diameter [mm]') @click.option('--trace-width', type=float, default=0.15) @click.option('--via-diameter', type=float, default=0.6) @click.option('--via-drill', type=float, default=0.3) @@ -99,7 +100,7 @@ def svg_file(fn, stuff, vbw, vbh, vbx=0, vby=0): @click.option('--clearance', type=float, default=0.15) @click.option('--clipboard/--no-clipboard', help='Use clipboard integration (requires wl-clipboard)') @click.option('--counter-clockwise/--clockwise', help='Direction of generated spiral. Default: clockwise when wound from the inside.') -def generate(outfile, windings, diameter, via_diameter, via_drill, trace_width, clearance, footprint_name, target_layer, +def generate(outfile, turns, diameter, via_diameter, via_drill, trace_width, clearance, footprint_name, target_layer, jumper_layer, twist_width, num_twists, clipboard, counter_clockwise): if 'WAYLAND_DISPLAY' in os.environ: copy, paste, cliputil = ['wl-copy'], ['wl-paste'], 'xclip' @@ -112,11 +113,25 @@ def generate(outfile, windings, diameter, via_diameter, via_drill, trace_width, svg_stuff = [jumper_path, out_path] pitch = clearance + trace_width - twist_angle = 2*pi / (windings * num_twists - 1) + twist_angle = 2*pi / (turns * num_twists - 1) twist_width = twist_angle * twist_width/100 via_diameter = max(trace_width, via_diameter) + # See https://coil32.net/pcb-coil.html for details + + d_inside = diameter - 2*(pitch*turns - clearance) + d_avg = (diameter + d_inside)/2 + phi = (diameter - d_inside) / (diameter + d_inside) + c1, c2, c3, c4 = 1.00, 2.46, 0.00, 0.20 + L = mu_0 * turns**2 * d_avg*1e3 * c1 / 2 * (log(c2/phi) + c3*phi + c4*phi**2) + print(f'Outer diameter: {diameter:g} mm') + print(f'Average diameter: {d_avg:g} mm') + print(f'Inner diameter: {d_inside:g} mm') + print(f'Fill factor: {phi:g}') + print(f'Approximate inductance: {L:g} µH') + + make_pad = lambda num, x, y: kicad_fp.Pad( number=str(num), type=kicad_fp.Atom.smd, @@ -155,8 +170,8 @@ def generate(outfile, windings, diameter, via_diameter, via_drill, trace_width, lines = [] arcs = [] - for n in range(windings * num_twists - 1): - for k in range(windings): + for n in range(turns * num_twists - 1): + for k in range(turns): r = diameter/2 - trace_width/2 - k*pitch a1 = n*twist_angle + twist_width/2 a2 = a1 + twist_angle - twist_width @@ -168,7 +183,7 @@ def generate(outfile, windings, diameter, via_diameter, via_drill, trace_width, xm, ym = r*cos(a3), r*sin(a3) arcs.append(make_arc(x2, y2, x1, y1, xm, ym)) - for k in range(windings-1): + for k in range(turns-1): r1 = diameter/2 - trace_width/2 - (k+1)*pitch r2 = diameter/2 - trace_width/2 - k*pitch a1 = n*twist_angle - twist_width/2 @@ -196,7 +211,7 @@ def generate(outfile, windings, diameter, via_diameter, via_drill, trace_width, lines.append(make_line(x1, y1, xv1, yv1)) a += twist_width - rs = diameter/2 - trace_width/2 - (windings-1)*pitch + rs = diameter/2 - trace_width/2 - (turns-1)*pitch rv = rs + trace_width/2 - via_diameter/2 x1, y1 = rs*cos(a), rs*sin(a) @@ -239,7 +254,7 @@ def generate(outfile, windings, diameter, via_diameter, via_drill, trace_width, name=name, generator=kicad_fp.Atom('GerbonaraTwistedCoilGenV1'), layer='F.Cu', - descr=f"{windings} winding twisted coil footprint generated by gerbonara'c Twisted Coil generator, version {__version__}", + descr=f"{turns} turn {diameter:.2f} mm diameter twisted coil footprint, inductance approximately {L:.6f} µH. Generated by gerbonara'c Twisted Coil generator, version {__version__}.", clearance=clearance, zone_connect=0, lines=lines, |