In this article, an experiment of the forced oscillating pendulum system was set up. Here, a pendulum is driven sinusoidally by the loudspeaker. From this experiment, the spectrum of output signal of a Halleffect sensor (UGN3503) which is used to transform the oscillatory motion of the pendulum into an electrical signal, exhibits four sharp frequency peaks, and it is also found that two of these frequency peaks cannot be described by the solution of ordinary differential equation from conventional ordinary differential equation text books. However, it can be solved by multi-time variable technique, a mathematical tool. The latter solution consists of the sum of four terms: Natural response, forced response and the two new terms being the result of multiplying between natural and forced responses. This analytical solution reveals the frequency components and their behaviors more precisely and corresponds well to the spectrum of the experimental result.

No abstract

This research aimed to study the possibility of producing the electricity from mechanical energy in the condensing unit of air conditioner. The electrical generator with the capacity of around 28 W was operated with the rotor motor of the condensing unit of air conditioner. Then, the electricity generator was tested with the room dimension of 6.60 m x 5.15 m x 2.60 m. The quantity of electric voltage, current, power, ambient and room temperature, ambient and room humidity was recorded for 3 days during a working period from 8 am to 5 pm. The results show that the electrical generator with the capacity of 28 W is suitable because it was not a load of motor in the condensing unit which was checked by the rotation frequency. Approximately 0.065 A of current, 85 V of voltage and 5.5 W of electrical power were constantly produced from the generator during the period of 8 am to 5 pm. The potential of electricity generation was around 14.1 W/day.

No abstract