A fan-type variable capacitor rotation angle sensor for university physics experiments

Abstract

In this article, we examine the rotation angle dependence of a hand-made fan-type variable capacitor for use in physics experiments in university classes. We made two circular bakelite plates, and the two terminal plates of the capacitor were 90° fan-type copper disks. The capacitance varied linearly with the rotation angle. The standard deviation from the linear fit was 1.4%, which was probably generated by the fact that the capacitor plates were not perfectly circular. Furthermore, we made a rotation angle sensing system using an AC high-pass filter. We selected the AC frequencies of 1 kHz and 100 Hz, which are easy to use in physics experiments. These experimental results also showed a linear relationship.

Constructing a capacitive rotating angle sensing system using a hand-made oscillator and testers

“…Figure 1 shows a photograph of the measurement system. A fan-type variable capacitor was made using two circular Bakelite plates of 100 mm diameter and 1.2 mm thickness [5]. A Cu adhesion seat (CU-35C, 3M Co., Ltd) was used for the terminal plates of this capacitor.…”

“…The variable capacitor and fixed 100 kΩ resistor R 8 were installed, as shown in figure 4. In our former study, the output voltage was proportional to the capacitance, and to the rotation angle at the frequency of 1.0 kHz and R 8 = 100 kΩ [5]. Therefore, we used R 8 as a 100 kΩ resistor.…”

“…It is important that they devise the structure of the sensor itself. To contribute to the purpose of this article, we present a sensor system using a fan-type capacitor [5] that can clarify some of the limitations shown below. We used the capacity change of a fan-type capacitor, as reported in a previous article, to an angle sensor [5].…”

“…To contribute to the purpose of this article, we present a sensor system using a fan-type capacitor [5] that can clarify some of the limitations shown below. We used the capacity change of a fan-type capacitor, as reported in a previous article, to an angle sensor [5]. Because an education effect is expected in each element (oscillator, amplifier, fan-type oscillator, and high-pass filter) of electronics that constitute a system, a student creates all of it by himself/herself after dividing it into separate projects.…”

“…In our previous study, we examined the rotation angle dependence of a hand-made, fan-type variable capacitor by means of a commercial oscillator and digital voltmeter [5]. In this study, a rotary angle sensor system was constructed by means of a hand-made oscillator, amplifier, and variable capacitor before the investigation.…”