Mechanical Buzzer - NINGBO SANCO ELECTRONICS CO., LTD.

Mechanical Buzzer

Mechanical Buzzer

SANCO`s Mechanical buzzer is a compact device capable o producing high sound pressure levels with minimum power consumption. This is achieved by the use of a self-contained, feedback controlled, transistorized oscillator circuit, housed completely within the device.

Sound Pressure and Distance
As there are differences in the measuring distances when manufacturers make the measurement of sound pressure, the following formula is recommended for calculation on occasions when a buzzer itself is tested or compared with a planned finished product.
However, as far as the calculated value is concerned, it is theretical one and therefore subject to change, depending upon circumstances and conditions.

OPERATION PRINCIPLE AND CONSTRUCTION
All models are low frequency devices (300 ~ 500HZ) which utilize an oscillating hammer to resonate a membrance. The Hammer is controlled by an electromagnetic assembly (Fig.1).
Fig.2 shows a typical circuit diagram utilized within each buzzer; the frequency of the oscillator circuit is approximately 1,000HZ, while the natural frequency of the hammer is 400HZ. When the current flows through the coil, L1 and the hammer begin to vibrate, another coil, L2 detects its vibration, providing feedback to a transistor so that the oscillator becomes synchronized with the vibrating hammer.SOLDERING
The miniature electro-magnetic transducer should not be exposed to extremely high temperature for prolonged period of time. As excessive heat will degrade the sealing performance of the unit, soldering should be conducted as quickly as possible.
Recommended Temperature and Time for Soldering Wave Soldering
(NORYL, PBT, PPS) 256℃--within 3 seconds
350℃-..within 1 secondsWASHING
Washable Type Transducers
Along with other electronic components, these transducers may be washed with cleaning solvents after the soldering process.
Non- Washable Type Transducers
Most cleaning solvents will be damaging to these transducers, wave soldering & washing should be prohibited.
Flux Removing Solvents
In the view of the recent requirement for total elemination of ozone-depleting chemicals, we have decided to recommend our customers to use deionized water for their cleaning process at the conditions given below, instead of [CFC" that was conventionally used.
Cleaning solvent.. Deionized Water
Solvent Temperature.. 55℃±5o

Sound Pressure and Distance
As there are differences in the measuring distances when manufacturers make the measurement of sound pressure, the following formula is recommended for calculation on occasions when a buzzer itself is tested or compared with a planned finished product. However, as far as the calculated value is concerned, it is theretical one and therefore subject to change, depending upon circumstances and conditions.

The formula is:

B=A+20 log (La/Lb)-A :Sound Pressure Value at distance La Ex.When the distance is doubled-B : Sound Pressure Value at distance Lb

B=A+20 log (la/Lb)=A+20 log (1/2) =A – 6.02 i.e. the sound pressure is apt to be reduced by 6.02 dB.

The table below is to shape up relations between the measuring distance variation and the sound pressure variation for reference.

TONE

The tone output, generated by buzzers, is essential in product design. A recommended way of selecting a desired tone is by listening to the different tones produced by the different buzzer. Additionaly, FFT analysis is usable for visual tone selection method. The sound is not an oscillation of a single frequency, but as a collected body of individual frequencies. The analysis is to diagnose the ratio of constituent frequencies. The following is a sample analysis of our typical buzzers.

SOUND ELEMENT

Element with Feedback Tab

This type of element has a tab form on the ceramic part. It used as the feedback function in a simple oscillation circuit , it will create a back voltage , or back EMF. to the internal circuit . Thus, the element operates automatically at the natural resonant frequency of the element and the loudness sound can be obtained.

Edge Mounting (External Drive Usage)

To fix the edge of the element to the supporting ring of the case. SPL depends on input frequency. However, considerable sound pressure can be obtained covering a wide frequency range around the resonant frequency.

Nodal Mounting (Self Drive Usage )

To fix the nodal diameter of the element to the supporting ring of the case. Loud sound pressure can be obtained at the resonant frequency. The SPL will drastically drop when the frequency is not at resonant point. This is the high efficient type of mounting for feedback type element.

Mounting Method for Sound Element

EDGE MOUNTING

NODAL MOUNTING