Tektronix TCP300A, User Manual

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Application Notes
Measuring Inductor Turns Count
To obtain an approximate turns count of an inductor, do the following. (See
Figure 24.)
1. Connect the inductor to a current limited source, as shown.
2. Measure the input current on one of the inductor leads.
3. Clamp the current probe around the inductor and note the current value.
Figure 24: Measuring the number of turns in a coil
The number of turns is equal to the ratio of coil current to input current. The
accuracy of this method is limited by the current measurement accuracy. The
following method allows more precise turns measurement.
For a more precise turns count, you need a coil with a known number of turns
to use as a reference.
1. Repeat steps 1 and 2 above and make the following changes:
2. Insert the reference coil into the current probe.
3. Insert the test coil into the current probe so that the currents oppose each other
as shown. (See Figure 25.)
Figure 25: Turns measurement using reference coil
40 TCPA300/400 Ampli fi ers and TCP300A/400 Series Current Probes User Manual