The inductance of a toroidal inductor can be determined through various methods, including the following commonly used ones:

1、 Using inductance measuring instruments

LCR meter: LCR meter (inductance, capacitance, resistance meter) is the most commonly used and convenient instrument for measuring inductance. Before measurement, it is necessary to calibrate the instrument, then connect the tested inductor to the test port according to the instrument's instructions, select the inductor measurement mode, and read the value. This method is direct, accurate, and suitable for inductance measurement in most situations.

Network analyzer: The network analyzer can measure the performance of inductance at different frequencies and obtain more detailed inductance characteristic curves. This method is suitable for in-depth research on high-frequency inductors and can provide more comprehensive inductance information.

2、 By observing the inductance identification

Some circular inductors may have markings, which may include information such as inductance and operating frequency. If the inductance value is marked on the inductor, it can be directly read. However, it should be noted that some inductors may use color rings or other encoding methods to identify their inductance, and in this case, it is necessary to refer to the corresponding encoding rules for interpretation.

3、 By calculation or estimation

For circular inductors that are not labeled or cannot be measured by instruments, one can try to determine their inductance through calculation or estimation. This usually requires calculation based on the structural parameters of the inductor (such as coil turns, coil diameter, magnetic core material, etc.) and operating frequency. However, this method is relatively complex and its accuracy depends on multiple factors, so it is generally not recommended as the preferred method.

4、 Practical precautions

Connection quality: When measuring a circular inductor, it is important to ensure a good connection between the testing fixture and the inductor to reduce the impact of contact resistance.

Environmental interference: Electromagnetic interference and temperature changes in the measurement environment can directly affect the measurement data, so measurements should be conducted in a stable environment as much as possible.

Multiple measurements: In order to reduce accidental errors and improve measurement reliability, it is recommended to conduct multiple measurements and take their average.

In summary, the inductance of a circular inductor can be determined by using inductance measuring instruments, observing inductance markings, calculating or estimating, and other methods. In practical applications, appropriate methods should be selected based on specific circumstances, and attention should be paid to details during the measurement process to ensure the accuracy of the measurement results.