07 · Consequences
Power, ratings & burnout
Parts have limits and the bench enforces them: design like it’s real, because here it is.
Ratings that bite
- LEDs tolerate ~30 mA continuously. Skip the series resistor at 5 V and one flare later it's an open circuit with a scorch mark.
- Resistors have a power rating (0.25 W default): P = I²R is checked continuously, and sustained abuse burns them open too.
- Fuses exist to die first: pick a current rating and put one in series with the supply. It blows on sustained over-current and saves everything downstream.
Burnout is thermal, not instant: brief spikes are survivable, sustained overload is not, just like the real part. A burned part stays burned until you press ⟲ Restart, which fits fresh parts and restarts from power-on.
Supplies
The battery (1.5–12 V, with internal resistance), the 12 V barrel jack, the 7805 linear regulator, and the buck converter cover most benches. The classic appliance pattern: 12 V jack → buck → 5 V rail → MCU vin, with the MCU's own 3.3 V output powering logic and sensors. That's exactly how the fume-extractor example is built.
A short circuit across a supply is detected and called out in the status bar; the sim keeps running so you can find it. Check wire colors and the hover tooltip: 0 V everywhere on a rail usually means the short is upstream of you.