- 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, N1 and N2, whose output signal lies between 1 and 10 kHz. Gates Na-N4 form an S-R bistable which is controlled by the out- puts of N1-N2, and drives the buzzer direct.
- Optimum effects are achieved when a simple ratio is set between the oscillator frequencies, e.g. 3:4.
- Piezoelectric resonators, also referred to as buzzers, are frequently used for providing audible signals in all sorts of electronic equipment.
- The spectral l composition of the output X signal is fairly complex, due to 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 ratio between the oscillator frequencies, which are adjustable with the aid of presets P1-P2. Note that diodes D1-D2 reduce the duty factor of the oscillator signals to about 25%.
- The resulting waveform is always composed of rectangular signals, but these differ in respect of their period to ensure that the buzzer pro- duces a rather agreeable sound. The buzzer driver is controlled by a logic level applied to point X. The quiescent current consumption is virtually negligible, while about 10 mA is drawn in the actuated state.
Tuesday, April 3, 2012
Piezo Buzzer Driver Circuit Diagram
Posted by Sulu M at 11:17 PM