WAVESPEED AI CIRCUIT SIMULATOR Your circuits stay on your device

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Free Online Circuit SimulatorDraw a circuit, press Run, watch the current flow.

Build analog circuits from resistors, capacitors, inductors, sources, switches, diodes, LEDs, Zeners and op-amps on a grid.
See every node's voltage in colour and the current as moving dots, read meters, and plot voltages and currents on a scope as time goes by.

DC and time-based simulationScope with several traces12 ready-made circuits

No sign-up No upload No watermark

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THREE SIMPLE STEPS

How to simulate a circuit

Place the parts

Click or drag resistors, capacitors, sources, diodes and op-amps onto the grid, and add a ground. Or start from one of the examples.

Wire them up

Drag from a terminal to where the wire should go. Wires join where they end on a terminal or on another wire, shown by a dot.

Run and measure

Press Run to watch the voltages and the current, flip switches, read the meters and plot any part's voltage or current on the scope.

What it simulates

The simulator works out every node's voltage and every part's current with nodal analysis, the method circuit textbooks teach. The DC operating point gives the steady state; the time-based simulation then steps forward with a fixed time step you can see and change, so capacitors charge, inductors ring and AC sources swing just as in the formulas.

Diodes, LEDs and Zeners follow the exponential diode equation, and op-amps have very high gain with their output limited to the supply voltages, so rectifiers, regulators, amplifiers and oscillators behave realistically. If a circuit has a short, a loop of voltage sources or a part that isn't connected, the simulator tells you which parts to look at.

Parts you can use

Part	What it does	What you can set
Resistor	Ohm's law: current = voltage ÷ resistance	Resistance
Potentiometer	A resistor with a sliding wiper: a variable divider or variable resistor	Total resistance, wiper position
Capacitor	Stores charge; blocks steady DC, passes changes	Capacitance, starting voltage
Inductor	Stores energy in its current; passes DC, resists fast changes	Inductance, starting current
DC source	A steady voltage, like a battery	Voltage
AC source	Sine, square or triangle wave	Amplitude, frequency, DC offset, phase
Current source	Pushes a fixed current	Current
Switch	Open or closed, flip it while the circuit runs	State
Diode	Conducts one way, about 0.6–0.7 V forward drop	—
LED	A diode that lights up with the current through it	Colour (red, yellow, green, blue, white)
Zener diode	Holds a steady reverse voltage	Zener voltage
Op-amp	Ideal amplifier, output limited to its supplies	Positive and negative supply
Lamp	A bulb that glows with the power it takes	Rated voltage and power
Voltmeter and ammeter	Show the voltage across or the current through a point	—
Scope	Plots voltages and currents over time, several at once	Which parts, time across the screen
Ground and wires	The 0 V reference and the connections	—

Tips for accurate results

Pick the time step for your signal

Use at least 50 steps per cycle of the fastest signal: 20 µs for 1 kHz, 1 µs for 20 kHz. Then pick a speed that shows a few cycles per second.

Start from the steady state

Press DC point to jump straight to the state a circuit settles into, then watch how it reacts when you flip a switch or change a value.

Always add a ground

Ground sets 0 V. Voltage colours, meters and the scope all read against it, and parts that aren't connected to it are pointed out.

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Circuit simulator FAQ

Is this circuit simulator free?

Yes. Every part, the scope, the examples, files and share links are included, with no account, no time limit and no watermark on exported images.

How do I simulate a circuit online?

Place parts on the grid, add a ground, drag between terminals to wire them and press Run. Voltages show as colours, current as moving dots, and meters and the scope show the numbers. It all runs in your browser with nothing to install.

Which components are included?

Resistors, potentiometers, capacitors, inductors, DC and AC sources, current sources, switches, diodes, LEDs in five colours, Zener diodes, ideal op-amps, lamps, voltmeters, ammeters and a scope with several traces.

Can I see how a circuit changes over time?

Yes. The simulation steps through time with a fixed time step you can see and change, so you can watch an RC circuit charge, an RLC circuit ring or a rectifier smooth an AC wave, and plot it all on the scope.

How accurate is it?

It solves the same equations circuit textbooks use and matches the formulas: a voltage divider gives R2/(R1+R2)·V, an RC circuit charges with time constant RC, an RLC circuit rings at 1/(2π√LC) and an inverting amplifier has gain −Rf/Rin. Use a smaller time step for fast signals.

How do I enter values like 4.7 kΩ or 100 nF?

Type them with SI prefixes: 4.7k or 4k7 for 4.7 kΩ, 100n for 100 nF, 2.2M for 2.2 MΩ, 10u or 10µ for 10 µ. The unit itself is optional.

What does the message about a short or a loop mean?

A short means a wire or a closed switch joins the two terminals of a source. A loop means voltage sources (or an inductor at DC) are connected in parallel with nothing between them. The simulator names the parts so you can fix the wiring, then press Run again.

Can I simulate op-amp circuits?

Yes. The op-amp is ideal with its output limited to the supply voltages you set, so amplifiers, comparators and oscillators work as expected. Open the inverting amplifier or the square wave oscillator example to start.

Does it work on a phone or tablet?

Yes. Tap a part to add it, drag to move it, drag from a terminal to draw a wire (or tap a terminal and then the end point), and pinch to zoom. The details panel slides up when you need it.

How do I save or share a circuit?

Your circuit is kept in this browser automatically. Save a circuit file to keep a copy or move it to another computer, copy a share link, or download the drawing as a PNG image.

Are my circuits uploaded?

No. The simulation runs in your browser and the circuit is saved in this browser's storage on your device. A share link carries the circuit after the # sign, which browsers never send to a server.

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