Simulation interactive

Surtension inductive

Coupez une bobine sans diode et regardez le pic qui tue les transistors.

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Watch the instant the transistor opens: the coil's current cannot stop, so the collector node flies to whatever voltage keeps it flowing — into avalanche with no diode (drawn at 300 V here; the real ceiling is your transistor's avalanche rating), or a harmless V + 0.7 through the flyback diode. Adding a series resistor kills the current faster but pushes the node back up by i × Rs — the trade every relay driver makes. The plot's window is always eight coil time constants (8 × L/R), so one release fills it whatever L and R you pick: raising L stretches the same shape instead of flattening it.