|A typical oscilloscope probe
circuit is shown below. This classic model has a X1 and a X10 position.
In the X1 position, the signal collected at the tip goes straight into the 1M
input of the scope.
In the X10 position the signal between the probe tip
and the scope input is attenuated by factor of ten by including a 9M resistor
between the probe tip and the scope input.
A trim capacitor in parallel
with the 9M resistor is included and is adjusted to form a clean square wave on
the scope screen, when the probe tip is connected to the 1KHz calibration
signal, which many scopes provide.
To change the probe to a X100
device, the 9M resistor has to be changed to 100M. The trim capacitor may
also have to be changed but often the existing cap will work. Adjust the trim capacitor for a
clean square wave signal shown in (c) to the right.
Data sheet for a X100 scope