The oscilloscope photo below shows this changing voltage ... are reasonable values for a meter. DIY HV probe resistors waxed For R1 I purchased 25 200MΩ high voltage resistors (MX440-200M ...

Once the voltage hits 3V, an LED is lit, indicating the presence of high voltage near the detector’s probe. A wire-wrapped resistor does double-duty serving as the probe while providing a high ...

Utilize analog and digital signal processing techniques in building a low-cost high-precision digital oscilloscope for high school use.