User Manual

Probing Principles
Extending DC Range
If you want to measure a low-amplitude AC component that is superimposed on an extremely large steady-state DC component
(such as in a power supply), or if you want to extend the DC current range of your probe, you can add offset (bucking) current with
a second conductor.
To supply additional bucking current:
1. Place a secon d conductor that has a pure
DC component of known value in the probe
jaw with the cond uctor und er test.
2. Orient the second conductor so that the
bucking current flows in the opposite
direction of the DC flow in the conductor
under test.
3. To determine mea s uremen t values, add
the value of the bucking current to the
displayed measurement.
NOTE. Adding a second conductor to the probe increases the insertion impeda nce and reduces the upper bandwidth limit of the
probe. Winding multiple turns further increases the insertion impedance, further reducing the upper bandwidth limit.
34 TCP0150 Current Probe Instruction Manual