January
2006, Issue 186
Electronic
Scarecrow
AUDIO
OUTPUT
One
method of scaring animals away is to startle them with
loud sounds. The remote station can output a sound file
using one of the MC9S08GT16 microcontroller’s timers
in PWM mode and drive an external amplifier/speaker
module.
The
amplifier is based on an STMicroelectronics TDA2822M
dual low-voltage amplifier configured in Bridge Drive
mode. Because the peak supply current can approach 1
A, it has its own high-current power switch. A divider
at the system’s input keeps the speaker from being overdriven.
An RC filter filters out the 16-kHz PWM carrier frequency.
