Xtronic runs your real Arduino code and solves the circuit it is wired into — voltages, currents, and anything those currents move. Read a sensor, drive a display, spin a gear train. It behaves the way the built thing would, and nothing you do to it costs a part.
Whatever you can wire, you can run. Free to start, no downloads.
Copper carries current, not colour. Every trace you draw is in the same solve as the code that drives it.
Compiled by the genuine Arduino toolchain and executed instruction by instruction. Not a lookalike written to be “close enough.”
The canvas is the machine, not a picture of it. Gears mesh when their teeth touch. Parts you sketch have real mass.
Every simulator is a model. Ours tells you where the model ends, in plain language, before you rely on it.
A mistake on screen costs nothing. The same mistake on a bench costs a burnt driver chip and two weeks waiting for replacements. The people most eager to experiment are the ones who can least afford to be wrong.
And every tool only covers half the project. Circuit simulators have never heard of your code. Code simulators fake the sensors, so they always tell you what you expected to hear. 3D tools animate motion no real current is driving. The moment your project does something physical — which is usually the moment it gets interesting — you are back to buying parts and guessing.
But a machine is one connected chain. Split it across three apps and every part looks fine while the real problem stays invisible: why the motor hums instead of turning, why the board resets when the gearbox binds, why code that worked on the bench stalls under load.
So Xtronic simulates the whole thing — and tells you how far it goes.
Find out what a circuit really does without destroying a part to learn it. Wire it wrong, read the warning, wire it again.
Work out the electronics and the firmware together, before ordering anything. Find out the design is wrong while it still costs nothing.
Give a whole class working hardware with no kits, no breakage and no shipping. Everyone starts from the same wiring.
Validate a board and its firmware before the prototype run, with the failure modes visible up front.
Drag in a board, a sensor, an indicator, whatever the design needs. Wire pin to pin. If it has moving parts, drop a gear on a shaft and slide it until the teeth touch.
The same sketch you would upload to a real board. analogRead, Serial, the Servo library — all of it.
Watch real physics. Voltages, currents, rpm and the serial monitor update as the machine actually behaves.
Most of what people build here never moves: a sensor read, an indicator, a timing loop, a circuit you want to understand before you solder it. Things that move are simply where other simulators stop and this one keeps going.
Everything in this list is wired on the same canvas and solved together — there is no separate mechanical mode to switch into.
Sketches are compiled by the genuine Arduino toolchain and executed instruction by instruction, so timing is timing. delay(), millis(), Serial, PWM and the Servo library work because it is the same compiled code. Serial monitor included.
Read a potentiometer and the number comes from the wiring you drew — not from a stand-in that always tells you what you expected.
Drop a gear onto a motor and it shares the shaft. Slide two gears until their teeth touch and they mesh, with the ratio taken from the tooth counts — not from a settings field. Backlash, friction losses and tooth-skip under excess torque are all modeled.
The motor's own back-EMF feeds into the same solve that lights your LEDs, so loading the drivetrain changes what the circuit does.
Draw a 2D outline, extrude or revolve it into a solid with real mass. It collides with everything else in the scene, and the collision genuinely loads the motor turning it. A mesh editor — grab, rotate, scale, extrude, bevel — is built in.
A live 3D view shows the assembly moving, animated by the same physics running the simulation.
Circuits, code, 2D sketches and 3D bodies are stored to your account and reopen exactly as you left them — wires, gear positions, sketch text and all.
The interesting part of hardware is what happens when it goes wrong — and every kind of wrong is available here. On a bench that costs money and a week of waiting. Here it costs a click.
Current spikes just like on a bench — with an overload warning instead of smoke.
It fails to hold its position, the way a servo asked for too much torque actually does.
It skips steps and loses position — the failure that is hardest to spot on real hardware.
The whole drivetrain stalls, and you can watch the current climb as it happens.
Every simulator is a model. Ours tells you where the model ends — before you rely on it, not after.
You do not need any of this to use Xtronic. It is here because the difference between a simulator and an animation is exactly this list.
Your circuit is solved by Modified Nodal Analysis, with backward-Euler transient analysis running while your code does — the same class of maths professional circuit simulators use. Capacitors charge on real curves, and motor winding inductance turns a PWM signal into genuinely chopped current with freewheeling through the driver’s body diodes.
Every time a pin changes, the circuit is re-solved and the result is fed straight back into the chip. digitalRead and analog readings come from your wiring, not from stubs. Servo pulse widths and buzzer tones are measured from the real signal edges.
The driver is modeled as switches and body diodes, so forward, reverse, coast and brake all emerge from the circuit itself — including regenerative braking that circulates current with zero battery draw.
Gear meshing is solved as a physical constraint: backlash dead zones, per-stage efficiency loss, and tooth skip once the tooth-force limit is passed. Motor back-EMF is fed back into the electrical solve, so mechanical load changes what the circuit does.
The servo runs a real position-control loop inside its published torque-speed envelope: it slews at the real spec speed, holds position, and fails to hold if you overload it. The stepper runs against a detent torque and misses steps under load.
Parts you sketch get exact mass, centre of mass and inertia computed from their geometry. Concave shapes are decomposed into up to 24 collision hulls, so a curved cradle actually cradles.
The physics is checked against values worked out by hand — because a simulator that produces plausible-but-wrong numbers is worse than none at all.
Hand-checked against theory:
stall current · RC charge curves
gear ratios · servo slew rate
No. Xtronic runs in the browser. There is nothing to download, no toolchain to set up on your machine, and nothing to keep updated.