Oscilloscope Captures 7/14/18: Picking up switching controller noise from laptop chargersodnupta (25)in #oscilloscope • 7 years ago (edited)Charger Plugged to Laptop Frequency reads about 98kHz We can tell that the charger uses 100kHz switching controller to regulate the voltage. Charger plugged off. Switching frequency increased to about 102kHz to match lower voltage required.