This paper presents a harmonic analysis of the output voltage from single-phase AC voltage controllers, comparing results from simulation and experimental methods. Key findings highlight the Total Harmonic Distortion (THD) variations with different firing angles, demonstrating that simulation results align closely with experimental data, especially between firing angles of 45° and 90°. The study concludes that significant harmonic presence necessitates filtering to protect devices, providing valuable insights for beginners in understanding AC voltage controller circuits.