The Vibration Sensor That Invented a 300 Hz Tone
A 900 Hz vibration can look like a clean 300 Hz signal when the ADC samples too slowly.
Archives: Case Files
The Transfer Function That Settled at 5, Not 20
A transfer-function numerator is not automatically the steady-state gain. Diagnose why H(s) = 20/(s+4) gives a unit-step final value of 5.
The RLC Circuit That Peaked Instead of Filtering
An inductor and capacitor do not always add opposition. At series resonance, their reactances cancel and current can reach its maximum value.
The Capacitor That Drew Too Much Current
A capacitor is open-circuit at DC steady state, but that does not mean startup current is zero. Diagnose a 10 mA switch-on current in an RC circuit.
The Parallel Load That Tripped the Supply
Adding a parallel branch does not simply split a fixed source current. Investigate why a source protected at 3 A trips when a second load is connected.
The Voltage Divider That Collapsed Under Load
A divider can be mathematically correct when unloaded and still miss its target once a finite load is connected. Diagnose why 6 V falls to 4 V.
The Circuit That Shouldn’t Have Burned
A correct current calculation does not guarantee a safe resistor. Investigate why a 2 ฮฉ resistor fails in a 12 V circuit even though Ohm’s Law checks out.