When to use: Draw a full schematic — resistors, capacitors, inductors, diodes, LEDs, transistors, op-amps, logic gates, AC/DC sources and more — by dropping parts on a snap-to-grid canvas, wiring pins together, then running a real DC operating-point analysis (▶ Run DC) or an AC steady-state phasor analysis (∿ Run AC). The DC engine assembles a Modified Nodal Analysis system, references it to ground, and solves it with Gaussian elimination (Newton–Raphson iteration for non-linear diode junctions). The AC engine rebuilds the same system with complex admittances (1/R, jωC, 1/jωL) at your source's frequency and solves it with complex Gaussian elimination, reporting node voltages, branch currents and dissipated power for DC, or magnitude and phase at every node for AC — viewable live on the built-in dual-channel Oscilloscope.
Every pin sits on an integer grid coordinate. Pins and wire endpoints that share a coordinate are merged into electrical nodes with a union–find pass. The solver stamps each component's conductance (Ohm's law), adds a current unknown for every voltage source (Modified Nodal Analysis), references the ground node to 0 V, and solves A·x = b by Gaussian elimination with partial pivoting. Diodes and LEDs are non-linear, so their exponential I–V curve is linearised and re-solved with damped Newton–Raphson iteration until it converges. The circuit must contain a Ground to provide a voltage reference.
This free online electronic circuit simulator lets you build DC and AC circuits with resistors, capacitors, inductors, voltage/current sources, LEDs, diodes, and switches, then instantly solve node voltages, branch currents, power dissipation, and AC magnitude/phase using nodal analysis — with a live dual-channel oscilloscope for AC waveforms — all in your browser, no download required.
The simulator applies Modified Nodal Analysis (MNA) to solve your circuit. It assigns a voltage variable to every node, writes Kirchhoff's Current Law (KCL) equations at each node, and solves the resulting matrix system (Ax = b) for all unknown node voltages.
For DC analysis, once voltages are known, branch currents follow from Ohm's Law (I = V/R) and power from P = V²/R or P = I²R. For AC steady-state analysis, the same matrix is rebuilt with complex admittances at the source frequency (resistor 1/R, capacitor jωC, inductor 1/(jωL)) and solved with complex Gaussian elimination, yielding a magnitude and phase for every node instead of a single real number — the same phasor technique taught in every undergraduate circuits course and used by professional SPICE-based simulators.
Resistors, capacitors, and inductors (any value in Ω/F/H with engineering-notation prefixes), independent DC and AC voltage sources, independent DC and AC current sources (with editable amplitude, frequency, and phase), LEDs and diodes (Shockley-equation forward-biased model with Newton–Raphson iteration), and open/closed switches. Wire up to 50 components and 30 nodes in a single schematic.
Each component has an editable Properties panel — click any element to change its value, label, orientation, or (for AC sources) frequency and phase. The probe tool lets you click any wire or node to read voltage and current in real time after pressing Run DC; press Run AC to solve the phasor system and open the Oscilloscope.
After running an AC analysis, the built-in Oscilloscope reconstructs v(t) = |V|·cos(ωt + phase) for any two circuit nodes you select as CH1/CH2, live, using the solved magnitude and phase from the phasor solution.
It behaves like a real bench scope: Time/Div and Volts/Div controls set the timebase and vertical scale, and a Pause/Resume toggle freezes the sweep so you can compare CH1 and CH2 amplitude and phase difference at a glance. Change the source frequency, amplitude, or a component value and re-run — the waveform updates to match, exactly as it would on real test equipment.
Voltage divider: two resistors in series from Vcc to GND — the midpoint voltage equals Vcc × R2/(R1+R2). LED current-limiting: a 5 V source, 330 Ω resistor, and LED in series — the simulator shows the 9.1 mA forward current.
Parallel resistors: two or more resistors between the same two nodes — total resistance equals 1/(1/R1 + 1/R2). Wheatstone bridge: four resistors forming a diamond — balance condition is R1/R2 = R3/R4. AC RC low-pass: an AC source into an R/C filter — run AC analysis and watch the Oscilloscope show amplitude rolloff and phase lag as frequency rises past the cutoff. Load these from the 📚 Circuits library or build from scratch.
Professional SPICE simulators (LTspice, Multisim, Tina-TI) support transient analysis, AC sweep across many frequencies, noise analysis, and thousands of component models including BJTs, MOSFETs, and op-amps. This simulator targets DC operating-point and single-frequency AC steady-state analysis for students, educators, and engineers who need a quick sanity check without installing software.
For real IC design, frequency sweeps, or PCB validation, use LTspice (free from Analog Devices) or the cloud-based Falstad circuit simulator. For learning fundamental circuit theory — KCL, KVL, Thevenin/Norton equivalents, and phasor/impedance analysis — this tool is the fastest way to verify your hand calculations and see the waveform on an oscilloscope in the same browser tab.
Yes — completely free with a registered EngineersUniverse account. No download, no subscription, no credit card. The simulator runs entirely in your browser using JavaScript.
Both DC and AC circuits: resistors, capacitors, inductors, DC/AC voltage sources, DC/AC current sources, LEDs/diodes, and switches. You can build voltage dividers, current dividers, Wheatstone bridges, LED driver circuits, RC/RL filters, and any linear network up to 30 nodes — solved either as a DC operating point or as an AC steady-state phasor solution viewable on the built-in oscilloscope.
Press ∿ Run AC to solve the circuit at your AC source's frequency using complex (phasor-domain) Modified Nodal Analysis — resistors contribute 1/R, capacitors contribute jωC, and inductors contribute 1/(jωL) to a complex admittance matrix, solved with complex Gaussian elimination. The result is a magnitude and phase at every node. The Oscilloscope panel then reconstructs v(t) = |V|·cos(ωt + phase) for two selected nodes in real time, with Time/Div, Volts/Div, and Pause/Resume controls like a real bench instrument.
Use nodal analysis: (1) choose a reference node (ground = 0 V); (2) write a KCL equation at each non-reference node — sum of currents leaving = 0; (3) express each current as (V_node - V_neighbor)/R; (4) solve the system of equations. The simulator does this automatically using matrix methods, but running through it manually is the best way to build intuition.
Common causes: (1) a voltage source with no return path to ground — every circuit needs a closed loop; (2) two voltage sources connected in parallel with different values (creates a contradiction); (3) a node with no resistive path to ground (floating node). Make sure every node connects back to GND through at least one resistor or voltage source.
Yes — it's ideal for checking circuit analysis problems from FE/PE practice exams. Build the circuit from the problem, run the simulation, and compare with your hand-calculated answer. It's especially useful for Thevenin equivalent circuits, maximum power transfer problems, and ladder networks.
A schematic tool (like KiCad or Eagle) captures the netlist for PCB layout — it draws the circuit but doesn't calculate voltages or currents. A circuit simulator (like this one, or SPICE) actually solves the equations and gives you numerical results. This tool does both: you draw the schematic and immediately get solved voltages and currents.
Yes — this is a free online circuit simulator that runs entirely in your browser, with nothing to install. Unlike desktop circuit simulation software (such as LTspice or Multisim), you just open the page, drag components onto the canvas, wire them, and click Run to solve the circuit. It works on any modern browser, including on a Chromebook or tablet.
Both terms apply: it is an electronic circuit simulator for component-level analysis (resistors, diodes, LEDs, transistors, op-amps) and an electrical circuit solver for DC networks — it computes the node voltages, branch currents, and power dissipation of the circuit you draw. "Circuit solver" simply refers to the math engine (here, Modified Nodal Analysis with Newton–Raphson for non-linear parts) that solves the circuit equations and returns numerical results.
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