With the continuous advancement of technology and the accumulation of experience, electronic measurement technology has developed rapidly, as well as in the measurement circuit of the balance machine. Transistors, integrated circuits, etc. are widely used, and the form of the printed circuit board for each part of the measurement is made into a separate unit. In order to facilitate maintenance, an inspection circuit is provided, and in the event of a failure, it can be directly determined which one of the printed circuit boards is damaged.

This section explains the basic issues of unbalanced measurements. When the unbalanced rotor rotates, the unbalanced centrifugal force acts on the two bearings supporting the rotor, and the bearing vibration caused by the force is converted into an electrical signal output by the sensor, and according to the correction plane separating circuit, the output signal amplitude corresponds to Unbalanced size. In addition, the phase of the output signal is compared to find an unbalanced angular position.

In the force measurement method, for example, when a load cell is used, the result is also that the small amplitude caused by the force is converted into an electrical signal output, so that the displacement of the bearing can be measured as well.

The horizontal component of the vibration displacement caused by the unbalanced centrifugal force is a sine wave having the same frequency as the rotational speed, but in the balance machine, the signal of the actual bearing displacement caused by the unbalanced rotor rotation, because the bearing of the balance machine and its structure As well as the influence of the rotor shaft, etc., there are generally many noises. Especially when the imbalance is small, the signal-to-noise ratio S/N is quite bad. Therefore, it is an important subject of the balancer measurement circuit to take out the unbalanced signal which is only the same frequency as the rotational speed from the vibration signal. Solving this problem and measuring the unbalanced phase are the two most important issues in balance measurement.