An eight-project Arduino simulator! Every project includes real Arduino code, a live circuit diagram, and a Serial Monitor at the bottom. 💡 LED Blink — The "Hello World" of hardware. A 220Ω resistor and LED circuit, digitalWrite(13, HIGH/LOW) code, and a PWM timing diagram all run simultaneously. 🔘 Button & LED — A live visualisation of INPUT_PULLUP. Click the button to light the LED, and see the inverted logic (LOW = pressed) explained in context. 🌓 PWM Fade — Controls LED brightness with analogWrite(9, 0–255). The PWM waveform and duty cycle update in real time as the LED breathes. 🌡️ Analog Sensor — Turn the potentiometer dial to read ADC values from 0 to 1023, then watch map() rescale them to the PWM range (0–255). Includes a voltage divider explanation. ⚙️ Servo Motor — Control the servo with an angle slider. The relationship between PWM pulse width (0.5ms – 2.5ms) and output angle is visualised live. 🎨 RGB LED — Mix any colour with the R, G, and B sliders. Press AUTO for an automatic rainbow cycle. A colour wheel is shown alongside. 📡 Ultrasonic Sensor — Shows how the HC-SR04 works with a TRIG/ECHO timing diagram. Verify the formula cm = round-trip time (µs) / 58 directly. 🚦 Traffic Light — Demonstrates a Finite State Machine (FSM). The RED → RED+YELLOW → GREEN → YELLOW cycle runs alongside a live state-transition diagram.