SPDT Center-Off: Three-Position Signal Routing

Select NC, center off, or NO to route one 5 V supply between two loaded outputs.

Try it

Click SW1 to cycle from center off to NO, then NC, then center off. To try spring return, change SW1’s Operating mode to Center-off momentary. Hold the upper throw for NC or the lower throw for NO; release to return to center. The two-position Latching and Momentary options remain available.

Expected behavior

All outputs start near 0 V in the center. Selecting a throw raises its loaded output to approximately 5 V. Inactive outputs remain near 0 V. Each 1 kΩ load draws about 5 mA on a 5 V rail.

How it works

The voltage probes measure the outputs relative to the common supply return. Probe colors match the chart traces. These idealized contacts change without bounce or transfer delay. Closed contacts use a small finite resistance; open contacts use a large finite resistance to keep the live simulation stable.