Capacitor in a simulator, free to use

Reference

Every one of its 2 pins

What it does

1

Either plate.

2

The other plate.

This part

What it does

A capacitor is the one part on the bench that genuinely integrates over time rather than answering instantly. It joins whatever else is on its nets into a shared analog solve, and the matrix works out the whole island together, which is what lets an RC network land on the true exponential curve rather than an approximation of one. Charging or discharging toward a fixed voltage through a fixed resistance, the result is exact for any time step, however large; what changes with the step size is only how finely a moving source is tracked in between. That is the part behind a 555’s timing, an RC debounce filter, and any circuit on this site where something changes gradually instead of switching instantly. It is still a simple model: there is no leakage, no equivalent series inductance, and no dielectric behavior beyond a small series resistance, only the charge and discharge curve itself, done properly.

Reference

The one property you can set

Property

Default

What it means

value

10

capacitance, in the unit the parts bin uses (microfarads). 10 is a typical decoupling or timing value; a 555 astable commonly uses 1 to 100.

How it is modeled

What is true about the Capacitor, here

What is modeled

The capacitor declares itself to the kernel as analog and then does nothing else at all. It reads its own voltage, V(1) - V(2), straight back off the solved nets for the probe. That is what lets an RC timing network land on the exponential to a tenth of a percent, and what puts a 555 timer's astable within 0.05% of the textbook formula, because the timing genuinely comes from the RC network and not from a rounded-off approximation of it.

Not modeled

It is not an ideal capacitor: there is 0.1 ohm of series resistance in it, which the analog island needs to stay well-posed. That is smaller than any real electrolytic's ESR and smaller than a wire, so it changes nothing a lesson measures, but it is there and it is not zero.

Every capacitor starts discharged. The operating point solved at power-on puts 0 V across every capacitor in the circuit, so a circuit is never resumed part-way charged.

No leakage, no dielectric absorption, no voltage or temperature coefficient, no self-resonance, and no polarity enforcement: an electrolytic-style value wired backwards behaves exactly as it does the right way around, where a real one would vent.

From Capacitor, in full.

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