SPDT Switch
A Single-Pole Double-Throw switch with three terminals: Common (C), Normally Open (NO), and Normally Closed (NC). The common terminal connects to NC at rest and flips to NO when activated.
Properties
| Property | Description | Default |
|---|---|---|
| Label | Display name shown on the canvas | SW1 |
| Initial position | Starting position when simulation begins (NC / NO) | NC |
| Contact resistance | Resistance of the active contact (Ω) | 0.05 Ω |
Simulation behavior
Click the switch during simulation to toggle between the NC and NO positions. The common terminal is always connected to exactly one of the two outputs — there is no open-circuit state (unlike a simple toggle switch).
Pin labels are displayed on the component body:
- C — common terminal
- NO — normally-open terminal (open at rest)
- NC — normally-closed terminal (closed at rest)
Tips
- Use an SPDT switch to select between two signal sources or two load paths without any break in continuity on the common terminal.
- Wire the NC terminal to a safe/default state (e.g., ground or a pull-down resistor) so the circuit behaves predictably at simulation start.
- Combine two SPDTs to build a DPDT (double-pole double-throw) that can reverse motor polarity.