In this study, we develop a capacitive rotating angle sensing system using a hand-made 1 kHz oscillator, field-effect transistor (FET) amplifier, and tester through a physics experiment conducted in Ryukoku University. Physics majors of the university can study the fundamentals of electronics through this system because it uses electronic elements, such as transistors and FETs. We fabricated the circuit of a rotation angle sensor system using a fan-type and coaxial variable capacitor. The capacitance of the variable capacitors varied linearly with the rotation angle. Owing to the CR high-pass filter, constructed by capacitors and a 100 k[omega] resistor, the output voltage of the system was linear with capacitors and the rotation angle. Not only can this system be used to teach university-level physics, but its applications could extend to various industries.