BC109C

5_12/05120611521331t.jpg","n10633c184.aspx","ecm 麦克前置放大器",true,false); ecm 麦克前置放大器 both transistors are low noise types. in the original circuit, i used bc650c which is an ultra low noise device. these transistors are now hard to find but bc109c are a good replacement. the circuit is very device tolerant and will set its quiescent point at roughly half the supply voltage at the emitter of the last transistor. the electret condenser microphone (ecm) contains a very sensitive microphone eleme ...

in this doorphone circuit,an 8 ohm speaker is used both as a microphone and also an output device. the bc109c stage amplifies in common base mode, giving good voltage gain , whilst providing a low impedance input to match the speaker. self dc bias is used allowing for variations in transistor current gain. an lm386 is used in non-inverting mode as a power amplifier to boost voltage gain and drive the 8 ohm speaker. the 10k potentiometer acts as the volume control, and overall gai ...

较大，所以还具有一定的使ha延时发声作用。c6为电源滤波电容器，它能够降低电池g的交流内电阻，避免电路产生阻塞振荡，相对延长电池使用寿命。 图2 所用元器件实物外形图 元器件选择 该制作总共用了19个电子元器件和配件，可对照图2所示的实物集体照一一进行配购。 晶体管vt1～vt3均用9014（集电极最大允许电流icm=0.1a，集电极最大允许功耗pcm=310mw）型硅npn小功率三极管，要求电流放大系数β＞200。实际上任何同类型的小功率、高增益晶体三极管（如3dg8、bc109c等），都可以在这里使用。vd用1n4148型硅开关二极管。 ha选用cpb14a12-4.0型自带音源微型直流压电陶瓷蜂鸣器，其外形尺寸及引脚排列如图3所示，它实质上是一个内含振荡电路和压电陶瓷片的有源发声器；它不需要外加任何音频驱动电路，只要接通直流电源就能直接发声，使用非常方便。cpb14a12-4.0的主要参数：外形尺寸为φ14mm×7.5mm，重量0.9g；发声频率为4.0±0.5 khz（连续单音），声压电平≥80db；直流工作电压范围3v～15v，工作电流≤7ma，工作温度范围 ...

相关元件pdf下载：bc109c 雷电预警装置 雷电会引起家庭失火，损坏家用电器，甚至危及人身安全。这里提供的装置可对雷电进行早期预警。 此装置实际上就是一个极其灵敏的静电检测器，它可以在发生雷击前，根据云层内部的放电而发出早期声光报警。由一根短导线构成的天线可检测半径3.2km范围内的云中放电。 当每次检测到云层放电时，蜂鸣器就发出报警声，或者led闪烁，从而可以给出较为充裕的时间来采取预防雷击措施如拔下调制解调器上的电话线、关断计算机电源并拔下插头等。 工作原理 电路原理见图1（点击下载原理图），此装置的基本特点是调整电路使逼近自激振荡状态。由图中所示的偏置电阻值可获得最佳的张弛特性。此振荡器为直流耦合，而反馈支路为晶体管tr1的集电极至tr2基极。环路总增益由多圈（12、18可20圈）预置电位器vr1设定。 电容器c3设定了tr2发射极的固定电位，而接在vr1滑动触点上的电容器c2在振荡时增加了相移。这里用的晶体管为bc109c，实际上任何同类的小信号、高增益晶体管都可用。 一旦触发起振，tr2的集电极就输出42khz的振荡信号，并经c4 ...

相关元件pdf下载：2n3906 bd140 bc109c this was one of the earliest circuits that i ever designed and built, in spring 1982. at that time i had only an analogue meter and a calculator to work with. although far from perfect, this amplifier does have a wide frequency response, low distortion, and is capable of driving an 8 ohm speaker to output levels of around 5 watts with slightly higher distortion. any power supply in the range 12 to 18 volts dc may be used. circuit descriptionthe amplifier o ...

相关元件pdf下载：lm386 in this doorphone circuit,an 8 ohm speaker is used both as a microphone and also an output device. the bc109c stage amplifies in common base mode, giving good voltage gain , whilst providing a low impedance input to match the speaker. self dc bias is used allowing for variations in transistor current gain. an lm386 is used in non-inverting mode as a power amplifier to boost voltage gain and drive the 8 ohm speaker. the 10k potentiometer acts as the volume control, and overa ...

相关元件pdf下载：bc109c bd139 2n3906 这个放大器有一种宽频率特性, 低畸变, 和是能驾驶一位8 欧姆报告人到大约5 瓦特的产品水平以轻微地更高的畸变。任一电源在范围12 到18 伏特dc 也许被使用。 放大器经营在类ab 方式下; 唯一470r 预先设定了电阻器控制淡静潮流流经bd139/140 免费产品晶体管。调整这里, 是一种交易在低畸变和低淡静潮流之间。典型地, 在淡静情况下, 备用潮流也许是15 ma 上升到150 ma 以50 mv 输入信号。 ...

相关元件pdf下载：bc109c ...

请问bc109c可以由谁代替请问bc109c可以由谁代替 ...