Abstract: A method for controlling a driving circuit. A first switch unit comprises a first switch and a second switch and a second switch unit comprises a third switch and a fourth switch. The first and second switch units are alternately turned on, and each switch is coupled to a blocking element in parallel. The first and second switches of the first switch unit are turned on simultaneously, and the first switch is then turned off. The second switch is turned off when the third and fourth switches are simultaneously turned on.

Abstract: A method for monitoring slope lands and buildings on the slope lands includes installing a light transceiver on a slope land and a light emission device on a location or a building corresponding to the light transceiver. When light emitted from the light emission device is received by the light transceiver, the light transceiver does not output signals. The light transceiver does not receive the light emitted from the light emission device when the dislocation or inclination occurs to the slope land and the light transceiver outputs a signal to alert a monitor center.

Abstract: A fan motor speed control circuit is disclosed. The circuit includes a digital/analog converting unit and a driving unit. The digital/analog converting unit takes charge of receiving a pulse width modulation (PWM) signal and converting it into a voltage signal. The driving unit is connected with the digital/analog converting unit in series for receiving the voltage signal, while the driving unit provides a first predetermined voltage level and a second predetermined voltage level as references. The fan motor is kept to run with a low constant rotation speed when the voltage signal level is higher than the first predetermined voltage level, with a full constant rotation speed when the voltage signal level is lower than the second predetermined voltage level, and with a variable rotation speed when the voltage signal level is lower than the first predetermined voltage level and higher than the second predetermined voltage level.