DPScope - Build Your Own USB/PC-Based Oscilloscope

Step 36 Assembly Step 23: Probe Compensation

• In the “Vertical” menu change the scale for both channels to 1V/div.

• In the “Acquisition” menu leave the averaging at “Avg 10”.

• In the “Levels” menu move the sliders “CH1” and “CH2” a bit below the middle.

• Connect the probes to the calibration outputs on the back side of the oscilloscope:

– Red grabber connects to “CAL” post

– Black grabber connects to “GND” post

• In the DPScope window on your PC select Utilities à Probe Compensation. A small window with instructions will pop up.

• With a small non-metal screwdriver you can now adjust the probe compensation capacitors (C18 and C19, respectively).

• On the right side you see examples for overcompensated, undercompensated, and compensated probes.

• The adjustment is correct when the displayed signals are nice square waves with sharp corners, i.e. when there is neither overshoot (sharp peaks after each transitions) nor slow settling (rounded edges).

• At the same time, you have tested the scope’s acquisition circuitry.