For a self- drive buzzer ( DC/ circuit- built), either pizeo or magnetic just apply the rated current and voltage.
For the external-drive buzzer, it depends on,
1. We should give magnetic buzzer 1/2 square wave, and provide it at least 3 times the amount of the rated consumptive current.
2. Otherwise, we give square wave to the peizo buzzer instead of 1/2 square wave, because the half wave might cause the buzzer does not work.
Therefore, voltage control is an important factor for a peizo buzzer which is driven by the voltage.
若是自激式Self-drive (DC/內含線路circuit-bulit in )的蜂鳴器,不管是電磁,還是壓電的,給予額定的電流及電壓即可,
而外激式External的蜂鳴器,因為工作原理的不同,)
電磁式蜂鳴器(Magnetic Buzzer)應給予1/2方波(square wave),及在啟動時,確保至少有三倍於額定消耗電流的電流,
壓電式蜂鳴器(Piezo Buzzer)的則給予方波, 若給1/2方波,極可能不會動作,因為只有半週的動作,
由於壓電式蜂鳴器,是靠電壓驅動,電壓的控制是重要的因素.
2007年6月23日 星期六
2007年6月13日 星期三
The sound which microphone received is too low 麥克風收到的聲音太小
There are three reason might cause the problems,
1. Lower sensitivity of microphone
The sensitivity of the condenser microphone is from -36 dB to -48 dB (0dB= 1V/Pa). If we use -44 dB microphones, the sound will be lower.
2. Defective design of amplifier
The impedance for the amplifier will affect the sensitivity and the frequency response.
Normally, the higher the impedance is, the better the sensitivity will be. However if the impedance is too high to get enough voltage/current, the high frequency response may get worse.
The lower the impedance is, the lower the SPL will be. The too much current will cause the insufficient voltage.
Input higher voltage will increase the sensitivity. Depend on the design of the amplifier and the frequency, the sensitivity might increases around 0.3 dB to 0.6 dB by 1 V.
3. Defective design of mechanism
The over-length or curved sound receiving holes leads to lower or unnatural sound.
麥克風所收到的音量太小,主要來自於三種原因,
1. 麥克風的靈敏度偏低
電容式麥克風的靈敏度大概介於-36 ~ -48dB之間(0dB=1V/Pa),若採用-44dB的麥克風,則可能收音的聲音會較小,
2. 放大線路設計不良
放大線路所匹配的阻抗,會影響麥克風的靈敏及高低頻的響應,
一般來說,匹配的阻抗愈高,麥麥克風的音量會愈大,但阻抗高到造成給麥克風的電壓/電流不足時,高頻的響應會變差.
阻抗愈低音量愈低,因為電流量太高使電壓不足.
給麥克風的電壓愈高,靈敏度也會增高,增加1V大約是0.3-0.6dB左右(視放大線路設計,頻率有所不同)
3. 機構設計不良
收音孔太長,或是彎曲,都會使收到的聲音變小或不自然,
1. Lower sensitivity of microphone
The sensitivity of the condenser microphone is from -36 dB to -48 dB (0dB= 1V/Pa). If we use -44 dB microphones, the sound will be lower.
2. Defective design of amplifier
The impedance for the amplifier will affect the sensitivity and the frequency response.
Normally, the higher the impedance is, the better the sensitivity will be. However if the impedance is too high to get enough voltage/current, the high frequency response may get worse.
The lower the impedance is, the lower the SPL will be. The too much current will cause the insufficient voltage.
Input higher voltage will increase the sensitivity. Depend on the design of the amplifier and the frequency, the sensitivity might increases around 0.3 dB to 0.6 dB by 1 V.
3. Defective design of mechanism
The over-length or curved sound receiving holes leads to lower or unnatural sound.
麥克風所收到的音量太小,主要來自於三種原因,
1. 麥克風的靈敏度偏低
電容式麥克風的靈敏度大概介於-36 ~ -48dB之間(0dB=1V/Pa),若採用-44dB的麥克風,則可能收音的聲音會較小,
2. 放大線路設計不良
放大線路所匹配的阻抗,會影響麥克風的靈敏及高低頻的響應,
一般來說,匹配的阻抗愈高,麥麥克風的音量會愈大,但阻抗高到造成給麥克風的電壓/電流不足時,高頻的響應會變差.
阻抗愈低音量愈低,因為電流量太高使電壓不足.
給麥克風的電壓愈高,靈敏度也會增高,增加1V大約是0.3-0.6dB左右(視放大線路設計,頻率有所不同)
3. 機構設計不良
收音孔太長,或是彎曲,都會使收到的聲音變小或不自然,
2007年6月12日 星期二
The relationship between Watt and SPL 瓦數愈大喇叭會愈大聲嗎?
Base on the premise that all the conditions are the same, if the drive circuit provides enough voltage, the speaker can generate higher sound pressure level. However, with the same voltage, but we use another speaker which applies higher rated power, it will be difficult to drive and output lower sound pressure level.
For example, a circuit can only provide the power of 8 ohm 1 W, in order to generate higher sound pressure level we collocate a 2W speaker, the SPL will be lower instead of higher. It is because with the increasing of the power, the diaphragm should be thickened. The coil also needs to be replaced by thicker wires. However, the thicker wires results in lower impedance so we have to wind a bit longer more, and that makes the coil heavier than before. Oppositely, if we use another speaker which loads lower power or with lower impedance, it is likely to make a little bit higher SPL, however the noise or burning down will possibly happen in this condition.
在所有條件一樣的前提,如果驅動線路提供足供電壓,喇叭的聲音是會比較大,
但如果驅動線路所能提供的電壓還是一樣,那換上額定功率愈大的喇叭,
就會發生所謂推不動的狀況,聲音反而會更小,
例如,線路只能發出8ohm 1W的功率,想要更大聲而換用2W的喇叭,反而會小聲,
因為隨著設計功率的加大,喇叭的振膜需要加厚,音圈也可能要換更粗的線,
更粗的線阻抗會降低,只好多繞長一點,音圈的質量就更重,
這些改變會使喇叭效率變差,也就是我們說的變小聲了,
反之如果我們換用承受功率小一點或是阻抗低一點的喇叭,
有可能會大聲一點,但要小心喇叭不會有破音,甚至燒毀的情形發生.
For example, a circuit can only provide the power of 8 ohm 1 W, in order to generate higher sound pressure level we collocate a 2W speaker, the SPL will be lower instead of higher. It is because with the increasing of the power, the diaphragm should be thickened. The coil also needs to be replaced by thicker wires. However, the thicker wires results in lower impedance so we have to wind a bit longer more, and that makes the coil heavier than before. Oppositely, if we use another speaker which loads lower power or with lower impedance, it is likely to make a little bit higher SPL, however the noise or burning down will possibly happen in this condition.
在所有條件一樣的前提,如果驅動線路提供足供電壓,喇叭的聲音是會比較大,
但如果驅動線路所能提供的電壓還是一樣,那換上額定功率愈大的喇叭,
就會發生所謂推不動的狀況,聲音反而會更小,
例如,線路只能發出8ohm 1W的功率,想要更大聲而換用2W的喇叭,反而會小聲,
因為隨著設計功率的加大,喇叭的振膜需要加厚,音圈也可能要換更粗的線,
更粗的線阻抗會降低,只好多繞長一點,音圈的質量就更重,
這些改變會使喇叭效率變差,也就是我們說的變小聲了,
反之如果我們換用承受功率小一點或是阻抗低一點的喇叭,
有可能會大聲一點,但要小心喇叭不會有破音,甚至燒毀的情形發生.
2007年6月7日 星期四
Piezo buzzer VS Magnetic buzzer
There are two types of buzzers, piezo and magnetic type.
A piezo buzzer generates sound because of the piezoelectric effect from the piezoelectric ceramic which drives the metallic diaphragm to vibrate. A magnetic buzzer is based on the electromagnetic principle, the metal diaphragm is pulled when input the power, and spring back without power.
The piezo buzzer is driven by square waves, and the magnetic buzzer needs 1/2 square waves to drive.
We suggest inputting higher voltage for a piezo buzzer, normally over 9V to have enough SPL. On the other hand, a magnetic buzzer can be driven to generate 85 dB by only 1.5V, but the consumption of the current will be much higher than Piezo one.
To compare the two types of buzzers, the magnetic type can have lower frequency response with the same dimension.
Though being limited by the dimension, the SPL of a magnetic buzzer can only reach to 90 dB. The piezo buzzer can achieve the SPL of 120 dB in some spec., some larger size can also easily reach to 100 dB.
蜂鳴器分為壓電式及電磁式的二大類,
壓電式蜂鳴器是以壓電陶瓷的壓電效應,來帶動金屬片的振動而發聲,
電磁式的蜂鳴器,則是用電磁的原理,通電時將金屬振動膜吸下,不通電時依振動膜的彈力彈回,
故壓電式蜂鳴器是以方波來驅動,電磁式是1/2方波驅動,
壓電式蜂鳴器需要比較高的電壓才能有足夠的音壓,一般建議為9V以上,
電磁式蜂鳴器,用1.5V就可以發出85dB以上的音壓了,唯消耗電流會大大的高於壓電式蜂鳴器,
而在相同的尺寸時,電磁式的蜂鳴器,響應頻率可以做的比較低.
電磁式蜂鳴器的音壓一般最多到90dB, 壓電的有些規格,可以達到120dB以上,較大尺寸的也很容易達到100dB.
A piezo buzzer generates sound because of the piezoelectric effect from the piezoelectric ceramic which drives the metallic diaphragm to vibrate. A magnetic buzzer is based on the electromagnetic principle, the metal diaphragm is pulled when input the power, and spring back without power.
The piezo buzzer is driven by square waves, and the magnetic buzzer needs 1/2 square waves to drive.
We suggest inputting higher voltage for a piezo buzzer, normally over 9V to have enough SPL. On the other hand, a magnetic buzzer can be driven to generate 85 dB by only 1.5V, but the consumption of the current will be much higher than Piezo one.
To compare the two types of buzzers, the magnetic type can have lower frequency response with the same dimension.
Though being limited by the dimension, the SPL of a magnetic buzzer can only reach to 90 dB. The piezo buzzer can achieve the SPL of 120 dB in some spec., some larger size can also easily reach to 100 dB.
蜂鳴器分為壓電式及電磁式的二大類,
壓電式蜂鳴器是以壓電陶瓷的壓電效應,來帶動金屬片的振動而發聲,
電磁式的蜂鳴器,則是用電磁的原理,通電時將金屬振動膜吸下,不通電時依振動膜的彈力彈回,
故壓電式蜂鳴器是以方波來驅動,電磁式是1/2方波驅動,
壓電式蜂鳴器需要比較高的電壓才能有足夠的音壓,一般建議為9V以上,
電磁式蜂鳴器,用1.5V就可以發出85dB以上的音壓了,唯消耗電流會大大的高於壓電式蜂鳴器,
而在相同的尺寸時,電磁式的蜂鳴器,響應頻率可以做的比較低.
電磁式蜂鳴器的音壓一般最多到90dB, 壓電的有些規格,可以達到120dB以上,較大尺寸的也很容易達到100dB.
2007年6月3日 星期日
What should I do to the noise? 有雜音怎麼辦?
The noise of an electret condenser microphone mostly comes from:電容式麥克風雜音大部份的原因來自於:
1. Impure current sourceIf the direct current mix with the alternating current signal, we will hear a stable level, low frequency and continual noise. We can lead the power to the microphone directly, or set a non-join circuit to filter the AC signal to improve the situation.
1. 電源不乾淨若是電源不乾淨(DC電中摻雜了AC信號),就會聽的到一個頻率穩定的雜音(通常是低頻),雜音音量的大小也差不多. 可改從電源處直接拉來給麥克風使用,或是加上退交聯線路,將AC信號濾掉.
2. Mechanism designThe faulty mechanism design might cause the wind sheer sound or resonant sound. Normally a deep curved sound hole is good to prevent the ESD, but it has some bad influence on the sound; for example, it is good for some frequency but some other frequencies might be declined. Therefore we may get unnatural sound with buzz or noise.
2. 機構設計不良機構設計不來可能會造成有風切聲,或是共鳴的聲音,太深又彎折的音孔,雖然有利於ESD的防範,但對聲音卻有很不好的影響,會對某些頻率增益,對另一些頻率則會衰減,使音色不自然,造成聽起來有嗡嗡聲或雜音的感覺.
3. The noise from signalMicrophone is a component to receive sound, which can receive wider frequency range than human ears. Both high and low frequency signal will transform into noise as a form of harmonic waves after being received. An obvious example is that the noise happens when the cell phone and the blue tooth are set too closely. Therefore when we design the microphone circuit, we should keep it away from the antenna or other components which might radiate signal.
3. 信號的干擾麥克風是收音的零件,能接受的信號範圍遠大於人耳,故一些高低頻信號在接受到後,可能會以諧波的方式,形成一些雜音,最明顯的例子就是與手機或是藍芽等裝置太過接近是就會有雜音出現,麥克風在設計電路時,要盡量與會發射信號的零件或天線保持遠的距離.
4. Outer noiseGenerally, the main noise is the sound of the wind. The users complain about the unclear sound because the higher join capacity receives the sound of the wind or breath. Modifying the join capacity (normally around 0.022~0.1 u) can solve this problem.On the other hand, if the outer sound (exclude the main sound) is too louder, it means the sensitivity of the microphone or the loading impedance is too high, what we can do is change to a low sensitive microphone or to decrease the loading impedance.
4. 外界雜音 一般此雜音都是風聲為主,使用者會抱怨聲音不清楚,很混濁,原因是麥克風交聯電容過大,把風聲或呼吸聲(氣音) 都收入而產生,只要把麥克風交聯電容改小(一般 0.022 ~ 0.1u )就可解決.如果是外界聲音(主要聲音以外的聲音)太大,表示麥克風感度過大,可改用低感度麥克風,或是因為麥克風的負載電阻太大 ,將負載電阻將低即可.
1. Impure current sourceIf the direct current mix with the alternating current signal, we will hear a stable level, low frequency and continual noise. We can lead the power to the microphone directly, or set a non-join circuit to filter the AC signal to improve the situation.
1. 電源不乾淨若是電源不乾淨(DC電中摻雜了AC信號),就會聽的到一個頻率穩定的雜音(通常是低頻),雜音音量的大小也差不多. 可改從電源處直接拉來給麥克風使用,或是加上退交聯線路,將AC信號濾掉.
2. Mechanism designThe faulty mechanism design might cause the wind sheer sound or resonant sound. Normally a deep curved sound hole is good to prevent the ESD, but it has some bad influence on the sound; for example, it is good for some frequency but some other frequencies might be declined. Therefore we may get unnatural sound with buzz or noise.
2. 機構設計不良機構設計不來可能會造成有風切聲,或是共鳴的聲音,太深又彎折的音孔,雖然有利於ESD的防範,但對聲音卻有很不好的影響,會對某些頻率增益,對另一些頻率則會衰減,使音色不自然,造成聽起來有嗡嗡聲或雜音的感覺.
3. The noise from signalMicrophone is a component to receive sound, which can receive wider frequency range than human ears. Both high and low frequency signal will transform into noise as a form of harmonic waves after being received. An obvious example is that the noise happens when the cell phone and the blue tooth are set too closely. Therefore when we design the microphone circuit, we should keep it away from the antenna or other components which might radiate signal.
3. 信號的干擾麥克風是收音的零件,能接受的信號範圍遠大於人耳,故一些高低頻信號在接受到後,可能會以諧波的方式,形成一些雜音,最明顯的例子就是與手機或是藍芽等裝置太過接近是就會有雜音出現,麥克風在設計電路時,要盡量與會發射信號的零件或天線保持遠的距離.
4. Outer noiseGenerally, the main noise is the sound of the wind. The users complain about the unclear sound because the higher join capacity receives the sound of the wind or breath. Modifying the join capacity (normally around 0.022~0.1 u) can solve this problem.On the other hand, if the outer sound (exclude the main sound) is too louder, it means the sensitivity of the microphone or the loading impedance is too high, what we can do is change to a low sensitive microphone or to decrease the loading impedance.
4. 外界雜音 一般此雜音都是風聲為主,使用者會抱怨聲音不清楚,很混濁,原因是麥克風交聯電容過大,把風聲或呼吸聲(氣音) 都收入而產生,只要把麥克風交聯電容改小(一般 0.022 ~ 0.1u )就可解決.如果是外界聲音(主要聲音以外的聲音)太大,表示麥克風感度過大,可改用低感度麥克風,或是因為麥克風的負載電阻太大 ,將負載電阻將低即可.
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