AC measuring circuit diagram

The figures (a) and (b) illustrate AC measuring circuits. Figure 21(a) presents a current measuring schematic diagram utilizing a magnetic balanced mode Hall device. When the magnetic field generated by the measured current, denoted as IN, is B1, this field induces a Hall voltage. If this voltage traverses through A1, the resultant current I2 is directed to the feedback coil N2. When the Hall voltage UH equals zero, I2 achieves a state of balance. Consequently, IN is proportional to N2, expressed as I2 = (N1/N2)IN. By employing a resistance R to measure I2, a value proportional to IN can be obtained. Figure 21(b) depicts a practical current measurement circuit. The Hall device utilized is the KH-400 made of InSb material. The constant current source circuit consists of an AD580, which supplies a control current of 5mA to H. A1 serves as an amplifier, where the amplified voltage is converted to current by A2. The output current of A2 is limited to below 20mA, necessitating the connection of a current buffer amplifier made up of VT1 and VT2 to the output terminal of A2. The voltage drop across R1 is displayed on the meter, representing the measured value.

The AC measuring circuits depicted in the figures utilize advanced sensing technology for precise current measurement. The magnetic balanced mode Hall device in Figure 21(a) operates by detecting the Hall voltage generated in response to the magnetic field produced by the current IN. This voltage is critical for achieving a balance in the circuit, which is essential for accurate measurements. The relationship between IN and I2 is directly proportional, allowing for the effective scaling of the measured current based on the turns ratio of the coils N1 and N2.

In Figure 21(b), the practical implementation of the Hall device is demonstrated using the KH-400, a high-sensitivity sensor made from InSb material, known for its excellent response in low magnetic fields. The constant current source, implemented with the AD580, ensures a stable 5mA control current, which is vital for the consistent operation of the Hall device. The operational amplifier A1 amplifies the Hall voltage, and the subsequent conversion to current by A2 allows for the measurement of very small currents, which are typical in sensitive applications.

To enhance the output from A2, a current buffer amplifier configuration using transistors VT1 and VT2 is employed. This configuration helps to isolate the output stage from the load, preventing any loading effects that could distort the measurement. The voltage drop across resistor R1 is directly related to the current flowing through it, and this voltage is what is ultimately measured and displayed on the meter, providing a clear and accurate representation of the current being monitored. This design highlights the importance of maintaining high sensitivity and accuracy in AC current measurements, making it suitable for various applications in electronic engineering and instrumentation.The figures(a), (b) are as shown, they are AC measuring circuits. The 21(a) is a current measuring schematic diagram of magnetic balanced mode Hall device. If the magnetic field produced by the measured current IN is B1, then B1 will produce Hall voltage. If this voltage passes though A1, the produced current I2 is fed to feedback coil N2. When th e Hall voltage UH=O, I2 reaches balance. Thus, INN1=fzN2, that is I2=(N1/N2)IN. If using resistance R to measure I2, then it can obtain a measured value which is in proportion to IN. The figure21(b) is as shown, it is a current measurement practical circuit. Hall device adopts KH-400 of lnSb material. The constant current source circuit is composed of AD580, it provides H with 5mA control current. A1 is amplifier, A1`s amplified voltage is changed to current by A2, it is lower than A2 output current, it is below 20mA, it is very tiny, so it should connect a current buffer amplifier which is composed of VT1 and VT2 to A2 output terminal.

R1`s voltage drop is shown on the meter, the shown value is the measured value. 🔗 External reference