## 2007年8月9日 星期四

### The interpretation of specification: Watt, Decibel, Hertz, and Resonance

W ( Watt ): A watt = a voltage x an ampere. For example, 330 Watt= 110V x 3 A.
V ( Volt ): V is the unit of voltage, when it needs one joule of work to sent one coulomb of electric from one point to another point, then the potential difference between these two points is one voltage. 
Ohm: Ohm is the unit of impedance in electronics, the higher the impedance is, the less electric current can pass through. 
Hz( Hertz): The frequency of the sound waves vibrate every second. For instance, 100Hz means 100 times vibration in one second. 
dB ( Decibel): dB is the unit of the sound pressure level, which is calculated with logarithm, because the susceptibility to the sound of human ears is not linear. 
Fo ( Resonance Frequency): Fo stands for the resonance point of the speaker. The lower the Fo is, the efficiency of the low frequency is better. 
S.P.L. ( Sound Pressure Level): The volume of the sound. 
Vo-p: The measurement from Vo to the peak, to drive the magnetic buzzer, the waveform is 1/2 square wave. 
Vp-p: The measurement from peak to peak, to drive the piezo buzzer. The waveform is square wave.
W (Watt) :瓦特, 一瓦特= 一伏特的電壓X一安培的電流, 330 Watt= 110V X 3 A.
V (Voltage): 伏特,表示電壓的單位,將一庫侖電荷由一點送到另一點，若須作一焦耳的功，則稱二點間之電位差為一伏特.
ohm : 歐姆,表示電子學上電阻阻抗的單位,阻抗愈高,能通過的電流愈少.
Hz (Hertz): 赫茲,波在每秒振動的次數, 100Hz = 一秒振動100次.
dB (deciBel) : 分貝, 表示音量大小的單位,是以對數算出來的,因為人耳對聲音的敏感度不是線性的.
Fo (Resonance Frequency) : 共振,用來表示喇叭的諧振點,頻率愈低,喇叭低頻的效果會愈好.
S.P.L. (Soudn Presure Level): 音壓位準,即音壓的大小值.
V0-p : 電壓從0V到峰值,用來驅動電磁式蜂鳴器, 波形為1/2方波.
Vp-p: 電壓的峰對峰值,,常用以驅動壓電式蜂鳴器,表示為方波的波形,