I think I'm not using the right buzzer in the operating frequency. I have to change the buzzer and then I don't think as big as 20V amplification is required. 10V may be ok. what do you think?
I think I'm not using the right buzzer in the operating frequency. I have to change the buzzer and then I don't think as big as 20V amplification is required. 10V may be ok. what do you think?
A piezo transducer is a high frequency whistle. It won't produce much sound at only 400Hz to 1100Hz.
A single transistor can't drive a piezo transducer. The driver must be push-pull.
Sound pressure must be stated at a certain distance. The distance for 85db might be only 10cm. At 20cm the sound pressure is only 79dB. At 40cm it is only 73dB. At an arm-reach distance the sound pressure is only 67dB.
Because a piezo is capacitive it needs to be discharged. You could connect a resistor in parallel with it to discharge it but it would limit the efficiency to <50% and wouldn't be very loud.
A piezo transducer does not produce a good mid-frequency analog sound because it ihas sharp high frequency resonances. The main resonance is somewhere between 3kHz to 5kHz so nearly any lower frequency will produce harmonics in that range and they will be very loud.
I think the resonances make it sound very distorted.