Probes and scope windows
Shift+PUpdated v2.4.4At a glance
- Click a wire to graph its net's voltage, click a part to graph the current through it — one tool, both
- Each probe gets its own movable, resizable, collapsible graph window that remembers where you put it
- Y auto-ranges to the trace's own peak, so a 3 mV ripple isn't a flat line beside a 12 V rail — or lock a scale to compare two windows
- Every window shares one X axis, so probes are always aligned, and the scrub cursor visibly un-draws the future as you drag back
- Probes are anchored by net NAME and by position, so they survive both renaming and rewiring — and report themselves lost rather than reading the wrong net
- Probes save with the document, so a board keeps the measurement setup you built on it
- Currents are sampled inside the solver, not once a frame, so nothing fast gets aliased into nonsense
Press Shift+P or the ⌖ button. Click a wire for its net's voltage. Click a part for the current through it. Clicking something already probed removes that probe — one tool, both directions.
Hovering highlights the whole net, not the segment under the cursor. A net is what gets measured, so a net is what lights up.
A probe isn't a schematic entity. It is never drawn on the sheet, never printed and never selectable — it exists visually as a graph window while the simulation is up. It does persist in the document, so a board keeps the probes you set up on it.
The windows
One window per probe: movable, resizable, collapsible, and it remembers its position and size between sessions. Colour rides on the probe itself, so it travels with the document.
- Y auto-ranges to that trace's own peak. A 3 mV ripple is a ripple, not a flat line beside a 12 V rail. Click the scale button to lock a fixed full-scale instead when you want two windows directly comparable; ± steps it through a 1/2/5 ladder.
- X is the whole capture window and is identical in every open window, so probes are always aligned with each other.
- The transport's scrub cursor is a vertical marker across all of them, and samples after the cursor are drawn dimmed — dragging the ruler backwards visibly un-draws the future while the readout reports the value at that instant.
- Collapsing keeps capturing. Only the drawing stops.
- Closing a window deletes the probe, this session and every future one. It's the only way to delete one, which is why leaving the workspace just hides them.
Probes that survive editing
A probe is anchored two ways at once, because neither survives real editing on its own:
- By net name. Stable when you move wires around. Not stable when nets get renumbered — unlabelled nets are numbered in pin order, so adding one part upstream can renumber them, and a probe that silently started reading a different net would look perfectly healthy.
- By position. Stable under renaming. Not stable under editing — move the wire and the anchor is over empty sheet even though the net obviously still exists.
So the name leads and the position repairs. A named net that still exists wins. When the name is gone, the position re-resolves and the probe silently re-binds to the same net under its new number. When both fail, the probe reports itself lost and reads nothing. It never guesses at a net that might be the one you meant.
Current probes have no positional fallback by design: a part either resolves or it's gone, and no coordinate could mean "this device".
On the sheet itself
Two overlays run while the simulation does, both toggleable from the transport:
Net voltage tint colours wires by the voltage on them, so you can see a rail sag or a node swing without probing it.
Current dots move along the wires at a speed derived from the current flowing. Speed scales against an auto-adjusting reference that rises instantly and decays slowly, so a microamp circuit still animates, an amp circuit doesn't strobe, and a momentary lull doesn't make the whole board flicker.
Direction is worked out across the net's whole wire graph rather than per segment, which is what keeps two wires meeting at a corner pointing the same way — a corner that contradicted itself would be a Kirchhoff violation drawn on your screen. Where a run is genuinely fed at its midpoint and drains from both ends, no direction is drawn at all, because one arrow per wire can't express that and inventing one would be a lie.
The dots are honest about being an approximation: a net doesn't have a current — devices do — so the animation uses the largest branch on the net. That's why the dots are the feel and the probe graphs are the measurement.