Examples and Visualizations¶

This page showcases the capabilities of KiCad-draw with interactive SVG visualizations. All examples generate both KiCad-compatible s-expressions and SVG visualizations for preview.

Circular Helix Coils¶

Circular helix coils are the classic spiral inductors commonly used in RF applications. They provide excellent Q-factor and are space-efficient for high-frequency designs.

Multi-Layer Circular Helix¶

This example shows a 4-layer circular helix coil with proper via connections between layers:

from kicad_draw.models import HelixParams
from kicad_draw.PCBmodule import PCBdraw

# Define parameters
params = HelixParams(
    x0=150.0,           # Center X coordinate (mm)
    y0=100.0,           # Center Y coordinate (mm)
    radius=11.0,        # Coil radius (mm)
    port_gap=0.65,      # Port opening size (mm)
    tab_gap=0.55,       # Tab extension distance (mm)
    angle_step=0.1,     # Angular step between layers (radians)
    layer_index_list=[0, 1, 2, 3],  # F.Cu, In1.Cu, In2.Cu, In3.Cu
    track_width=0.5,    # Main trace width (mm)
    connect_width=0.2,  # Connection trace width (mm)
    drill_size=0.2,     # Via drill diameter (mm)
    via_size=0.4,       # Via outer diameter (mm)
    net_number=1,       # KiCad net number
    segment_number=100, # Number of arc segments
)

# Generate the coil
pcb = PCBdraw(stackup="default_6layer", mode="file")
pcb.draw_helix(params)

# Visualize
svg_content = pcb.visualize(visible_layers=[0, 1, 2, 3], show_vias=True)

All Layers Visible¶

This visualization shows all 4 layers of the circular helix with different colors for each layer:

Outer Layers Only¶

This shows only the front copper (F.Cu) and inner layer 3 (In3.Cu) to highlight the overall coil structure:

Key Features:

Consistent via spacing: Vias are positioned with ~0.68mm spacing
Proper layer connections: Each layer connects to the next via tabs and vias
Angular offset: Each layer has a slight angular offset for optimal magnetic coupling

Rectangular Helix Coils¶

Rectangular helix coils offer better space utilization in constrained layouts and can provide different inductance characteristics compared to circular coils.

Multi-Layer Rectangular Helix¶

This example demonstrates a 4-layer rectangular helix with rounded corners and port connections:

from kicad_draw.models import HelixRectangleParams
from kicad_draw.PCBmodule import PCBdraw

# Define parameters
params = HelixRectangleParams(
    x0=150.0,           # Center X coordinate (mm)
    y0=100.0,           # Center Y coordinate (mm)
    width=30.0,         # Rectangle width (mm)
    height=20.0,        # Rectangle height (mm)
    corner_radius=3.0,  # Corner rounding radius (mm)
    layer_index_list=[0, 1, 2, 3],  # F.Cu, In1.Cu, In2.Cu, In3.Cu
    track_width=0.5,    # Main trace width (mm)
    connect_width=0.3,  # Connection trace width (mm)
    drill_size=0.2,     # Via drill diameter (mm)
    via_size=0.4,       # Via outer diameter (mm)
    net_number=1,       # KiCad net number
    port_gap=0.65,      # Port opening size (mm)
    tab_gap=0.55,       # Tab extension distance (mm)
)

# Generate the coil
pcb = PCBdraw(stackup="default_6layer", mode="file")
pcb.draw_helix_rectangle(params)

# Visualize
svg_content = pcb.visualize(visible_layers=[0, 1, 2, 3], show_vias=True)

All Layers Visible¶

This visualization shows all 4 layers of the rectangular helix:

Outer Layers Only¶

This shows the front copper and inner layer 3 to highlight the rectangular structure:

Key Features:

Consistent via spacing: Now matches circular helix with ~0.65mm spacing (after our fix!)
Proper tab alignment: Bottom tab of each layer connects to top tab of previous layer
Rounded corners: Smooth transitions reduce current concentration
Port connections: Tabs extend horizontally for easy external connections

Side-by-Side Comparison¶

This example shows both circular and rectangular coils in the same design for direct comparison:

Comparison Highlights:

Size efficiency: Rectangular coils can fit better in constrained spaces
Via spacing: Both now have consistent spacing (~0.65mm)
Connection style: Different tab orientations for different layout requirements
Magnetic coupling: Different field patterns for different applications

Layer Legend¶

The visualizations use the following color scheme:

Red: F.Cu (Front Copper, Layer 0)
Blue: In1.Cu (Inner Layer 1)
Green: In2.Cu (Inner Layer 2)
Orange: In3.Cu (Inner Layer 3)
Purple: B.Cu (Back Copper, Layer 5)
Black circles: Vias with drill holes

Export Options¶

All examples can be exported in multiple formats:

KiCad S-Expressions¶

# Export for direct paste into .kicad_pcb files
s_expressions = pcb.export()
print(s_expressions)

SVG Visualization¶

# Generate interactive SVG
svg_content = pcb.visualize(
    visible_layers=[0, 1, 2, 3],  # Choose which layers to show
    show_vias=True,               # Show/hide vias
    width=800,                    # SVG width in pixels
    height=600                    # SVG height in pixels
)

File Output¶

# Save to KiCad PCB file
pcb.save("my_coil_design.kicad_pcb")

# Save SVG to file
with open("my_coil_visualization.svg", "w") as f:
    f.write(svg_content)

Design Guidelines¶

Via Spacing Optimization¶

Both circular and rectangular helix functions now use consistent via spacing
Spacing is primarily controlled by the port_gap parameter
Smaller port_gap values create tighter coil windings

Layer Selection¶

Use consecutive layers for best magnetic coupling
Consider stackup impedance when choosing layers
More layers = higher inductance but also higher resistance

Geometric Parameters¶

Circular: Optimize radius and angle_step for desired inductance
Rectangular: Adjust width, height, and corner_radius for space constraints
Both: Match track_width to your PCB design rules

Troubleshooting¶

Common Issues¶

Vias not aligning: Fixed in recent updates - tabs now properly align between layers
Inconsistent spacing: Fixed - both coil types now use the same spacing algorithm
Overlapping traces: Increase port_gap or adjust layer count

Verification¶

Always verify your generated coils by:

Checking the SVG visualization
Running DRC in KiCad after importing
Confirming via connections in 3D view

These examples demonstrate the latest improvements to KiCad-draw, including the tab alignment fix and via spacing consistency improvements.