1. What is the difference of a transducer and buzzer?

ANS: Transducer is external-drive and need to input AC voltage and signal while buzzer is installed with circuit inside and only needs DC current and voltage to drive it.

2. How do I drive a magnetic transducer?

ANS: An operating voltage and frequency signal is required. Usually 3 times of the rated current will be needed to trigger up the vibration of the weight diaphragm. Square wave is suitable for magnetic type and sign wave is suitable for piezo type.

3. How do I drive a magnetic buzzer?

ANS: DC voltage and certain amount of current are required.

4. Can a transducer play melody?

ANS: Transducer outputs sound save complying with the input signal while the resonant signal input gives you the maximum sound pressure level (SPL) output.

5. Why does my buzzer have noise?

ANS: Improperinput can lead to noise. If the input voltage is too high, the weight diaphragm can probably get? excited? hitting by other structure inside the chamber, and hence causes noise. A wrong frequency can also lead to noise. For instance, if the rated frequency is 3100Hz, but the user inputs 2730Hz, the noise appears easily, especially within the range 10% ahead of the rated frequency because this range gives you the highest SPL.

6. What are the differences between magnetic type and piezo type?

  Piezo Buzzer Magnetic Buzzer
Working Theory Piezo Electirc Effect Electro-magnetic Effect
Size 10-50mm 4-25mm
Resonant Frequency 2-6kHz 1-3kHz
Operating Voltage 9-48V 1.5-12V
Sound Level 85-120dB 70-95dB
Current Consumption 5-20mA 35-60mA

7. Noise appears when recording using a condenser microphone?

  • Impure current source: When DC current mixes with AC current signal, a stable, low frequency and continual noise will appear. To solve just separate the AC and DC current input simply by setting a filter out the AC signal.

  • Design fault: A deep curved sound hole is better preventable to ESD but it may dispel some certain frequency of sound. Designer will need to trade off and take the balance.

  • Interference of disturbing signal: The frequency reception range of a microphone is greater than human's ear. Some ultra high and low frequency signal will transform into noise as a form of harmonic waves after being received. For instance, when designing a blue tooth earphone, we have to keep the antenna away from other signal radiating components.

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