Browser Circuit Simulator and Schematic Editor

A browser-based electronic circuit simulator with drag-and-drop components, a wire tool, and real-time voltage, current and power readouts. Build circuits with batteries, resistors, potentiometers, LEDs, diodes, capacitors, inductors, transistors, switches, fuses, lamps, buzzers and motors, rotate and delete parts individually, connect them with wires and run a DC analysis — or drive it with AC and read the waveform on the built-in oscilloscope. Load example circuits or create your own — the simulation runs right in your browser.

How to Use the Circuit Simulator

1
Add components

Tap a component in the palette to drop it on the canvas. Select it to edit its properties and to rotate, copy or delete it right in place.

2
Connect with wires

Drag from one component terminal to another to draw a wire, or switch to the Wire tool and tap two terminals. A wrong wire can be removed on its own: tap it and press the trash button.

3
Simulate

Press Simulate to run the DC analysis. Voltage, current and power are shown on each component, current flow is animated through the wires, and overloads are flagged with clear warnings.

Design and simulate electronic circuits with an interactive drag-and-drop editor

Components
Power
Passive
Semiconductors
Loads & switching
Logic & ICs
Add components from the palette and drag a wire from one terminal to another. Tap a part or a wire to select it — rotate and delete buttons appear right next to it. Then press Simulate.
Properties
Tap a component to edit it, or add a component from the palette onto the canvas. Rotate, duplicate and delete buttons appear right on the selected part.
Example Circuits

Features

Twenty-plus components: transistors, MOSFET, logic gates, relays and a smart block
From batteries and resistors to NPN/PNP transistors, a MOSFET, an op-amp, logic gates, relays, sensors and a programmable smart block.
Rotate, duplicate and delete any single part or wire
Tap a part or a wire to select it and on-canvas buttons appear to rotate, copy or delete it — so removing one wire no longer wipes the whole circuit.
Full undo and redo history
Every action — adding, moving, wiring or deleting — can be undone and redone with the buttons or Ctrl+Z / Ctrl+Y.
Real DC analysis (modified nodal analysis) with per-component V, I and P
Solves the node-voltage equations of the whole circuit, accounts for battery internal resistance and labels each part with its actual voltage, current and power.
Clear overload warnings instead of cryptic errors
An LED with no resistor, a short circuit, a blown fuse or an over-power part are explained in plain language with a hint on how to fix it.
Live animation: glowing LEDs and lamps, a spinning motor, current along the wires
LEDs and lamps glow in proportion to the solved current, the motor spins, and dots along the wires show the current direction.

FAQ

What’s the difference between the real and ideal model?

Real includes the resistance of the battery, LEDs and diodes, and wires — the numbers come out like a real board (an LED draws about 18.7 mA instead of an even 20). Ideal zeroes those resistances and gives the clean textbook values. On simple circuits the difference is tiny; on LEDs and low-resistance circuits it is noticeable. Real is the default.

What components are available?

Battery and current source, resistor, potentiometer, photoresistor and thermistor, capacitor, inductor, diode, LED, NPN/PNP transistor, MOSFET, op-amp, AND/OR/NOT and other logic gates, switch, push button, relay, fuse, lamp, buzzer, motor, a programmable smart block and ground. The set keeps growing.

How do I delete a single wire or component without clearing everything?

Tap a wire or a part to select it and a small bar appears next to it. For a component it has rotate, duplicate and delete; for a wire it has delete. On a computer the Delete key works too, and any deletion can be undone with the Undo button or Ctrl+Z.

Can I rotate components?

Yes. Select a part and press the rotate button (or the R key) to turn it by 90°. Wires stay attached to the terminals and reroute automatically.

Why do I get a warning when I connect an LED without a resistor?

An LED has almost no resistance of its own, so wiring it straight to a battery pushes a very high current through it and in reality it would burn out. The simulator computes the real current, shows an overload warning and suggests adding a current-limiting resistor — just like on a real bench.

How is the transistor modelled?

The transistor works as a controlled switch: when the base-emitter voltage reaches about 0.7 V, the collector-emitter path turns on (saturation). This suits switching and logic circuits; linear β gain is not modelled in this version.

Does it support AC circuits?

Yes. There is an AC voltage source (~), a step-down/step-up transformer and a bridge rectifier — enough to build a full power supply — and the oscilloscope plots the waveform over time. The transformer is idealised: it scales voltage by its turns ratio and conserves power (a real transformer needs AC, but the ideal one also scales DC). At DC a capacitor is treated as open and an inductor as a short (steady state).

Can I save my circuit?

Your circuit is saved in your browser automatically, so it is still there when you come back. You can also export the schematic as a PNG image.

Does it work on mobile?

Yes, the editor is built for touch: tap to select, drag to move, drag from a terminal to wire, and pinch to zoom. The rotate and delete buttons are large and appear right next to the selected part.

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Who is this tool for?
🎓 Students 🔌 Electronics Enthusiasts
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