POWER	APPLICATION FILE PAGE
POWER.DSN POWER.ASM	Proteus VSM design file created as ISIS interactive schematic Source code file created using text editor within ISIS interactive schematic
OPERATION Three types of output power interface are shown. The relay is a simple interface, operating as an electrically operated switch, and suitable for a wide range of loads. It is driven via a bipolar transistor current amplifier. The triac is used for switching ac loads, such as the mains supply. The opto-isolator safely separates the MCU from the high voltage circuit. The oscillator drives a loudspeaker to produce, for example, an alarm signal. A hardware (555 timer) is used to relieve the MCU of generating the signal, and a BJT drives the speaker. The push button and MCU program simply allow each interface to be selected in turn.