Buzzer Driver

EE JULY/AUGUST 1987 Piezoelectric resonators, also referred to as buzzers, are fre- quently used for providing aud- ible signals in all sorts of electronic equipment. Buzzers are small, light, simple to use, and yet provide a loud output signal. They are either of the passive or of the active type. The former are driven by an AF signal source, while the latter feature a built-in oscillator, and require a direct voltage only. This circuit is a double AF oscillator for driving passive buzzers. It ensures a richer out- put sound than normally obtain- able from a piezo buzzer due to the use of two oscillators, Ni and N2, whose output signal lies between 1 and 10 kHz. Gates N3-N4 form an S-R bistable which is controlled by the out- puts of NI-N2, and drives the buzzer direct. The spectral composition of the output signal is fairly complex, due to ZZER the presence of both the fun- damental notes and the differ- ence and sum frequency. The timbre so obtained varies as a function of the ...