Interactive simulation
Where the diode curve meets the resistor's load line — that's your operating point.
The dashed load line pivots as the source and series R change; the pulsing Q point is where the circuit constraint and the diode physics agree. Try the Zener in Reverse to watch it clamp near −5.1 V. The circuit sketch above the graph is live — polarity marks, LED glow and the travelling charge dots all follow Q.
What you can change
LED series resistorNobody wires just one LED. Each string is its own series chain of LEDs behind its own resistor — stringing more LEDs raises the headroom the resistor has…
H-bridge motor driverForward, reverse, brake, coast — watch the current thread the bridge.
I2C rise timeThe pull-up has to charge every picofarad on the bus — watch the edge lose the race to the clock.
Inductive kickbackSwitch a coil off without a diode and watch the spike that kills transistors.
LC tank energyEnergy sloshing between coil and capacitor while R taxes it away.
Logic gatesToggle the inputs and watch AND, OR, XOR and friends light up.
Op-amp gain & clippingRaise the gain until the sine flattens against the rails.
Op-amp integratorA square wave in, a triangle out — and the DC offset that quietly walks the output into the rail.
PID controllerTune Kp / Ki / Kd on a live thermal loop — overshoot, settling, disturbances.