Make a light turn on
A battery supplies energy. A switch opens or closes a path. An LED is a tiny light. In this lab, connect Battery → Switch → Resistor → LED, then turn the switch ON.
BUILD · CONNECT · DISCOVER
Circuit Lab
Little connections. Bright ideas.
Build a circuit, flip a switch, and see what lights up.
Tap the switch to turn it ON.
Ready to make something light up?
OUT dots send signals. IN dots receive them. Wires that cross do not join.
A SPARK OF SCIENCE
What can you discover?
Teach your circuit a rule
An AND gate needs both inputs ON. An OR gate needs at least one input ON. A NOT gate flips a connected input: OFF becomes ON, and ON becomes OFF. All gate inputs need wires.
Try a resistor
Real resistors limit current and help protect LEDs. Here, a resistor makes an LED dimmer. Try comparing two LEDs connected to the same battery: one with a resistor and one without.
Hold a pushbutton
A switch stays ON until you flip it again. A pushbutton sends a signal only while you hold it. Hold with your mouse or finger, or focus it and hold Space or Enter. Let go to turn the signal OFF.
Make a doorbell
A buzzer turns a signal into sound. Connect Battery → Pushbutton → Buzzer. Buzzers start muted: choose Sound: on to hear a quiet tone. The ON label and yellow wires still work with sound off.
Spin a motor
A motor turns electrical energy into movement. In this lab, an ON signal spins a little fan. With Sound on, it also makes a quiet hum. Try Battery → Switch → Motor, then connect an LED to the same switch. Can one switch control both?
For curious kids, parents and teachers: how this lab works
Circuit Lab is a simplified signal playground for exploring cause and effect. Yellow wires carry an ON signal; pale wires are OFF or incomplete. Wires travel from an OUT dot on the right to an IN dot on the left. One output can feed several inputs; each input accepts one wire. Crossing wires stay separate. Feedback loops are not supported.
The board hides the power and return connections for its parts, including gates, LEDs, buzzers and motors. Real circuits need a complete path back to the battery, correctly oriented LEDs, a suitable resistor, and separate power connections for logic chips. This lab does not calculate volts, amps, ohms, component damage, motor speed or real LED brightness. Each resistor reduces the displayed signal brightness; a gate makes a fresh ON or OFF signal. Buzzers and motors respond to any ON signal. Use this as an introduction, not as a wiring plan for real electronics.
Despite its route name, this is a component-based circuit builder, not the Wireworld cellular automaton. Your board is stored in this browser on this device. Use Save file to keep or share a copy. Held pushbuttons are always released when a board opens. Sound starts off on each visit and pauses when you leave the page.
Keyboard: Tab to any part or dot, then Enter or Space to use it. Hold Space or Enter on a pushbutton; release the key to turn it OFF. With a part tool or Move selected, focus the board and use arrow keys, then Enter to place. Escape cancels a wire or move. Delete removes a selected part. Ctrl/Command + Z undoes.