|
|
|
 数字功放电路 | | 数字功放电路 | | CAR AMPLIFIER 1X100W Schematic | | | | 测量放大器的输入级问题！ | | 精品电路图供大家参考。 | | 前向通路电路 | | | | 前向通路（多路） | | | | 放大整形分频电路 | | | | 放大电路参考 | | | | 音量控制电路 | | 音量控制电路
Based on the classic Baxendall tone control circuit, this provides a maximum cut and boost of around 10dB at 10K and 50Hz. As the controls are passive, the last transistor provides a slight boost. The output is designed to feed an amplifier with input impedance of 10k to 250k. | | 三带图形均衡器 | | 三带图形均衡器
Using a single op-amp this easy to make equalizer offers three ranges, low frequency,mid frequency,and high. With component values shown there is approximately +/-20dB of boost or cut at frequencies of 50Hz, 1kHz and 10kHz. Supply voltage may be anything from 6 to 30 Volts. Maximum boost 20dB is only realized with maximum supply voltage. | | 计算机麦克风电路图 | | 计算机麦克风电路图
The sound card for a PC generally has a microphone input, speaker output and sometimes line inputs and outputs. The mic input is designed for dynamic microphones only in impedance range of 200 to 600 ohms. Lazar has adapted the sound card to use a common electret microphone using this circuit. He has made a composite amplifier using two transistors. The BC413B operates in common emitter to give a slight boost to the mic signal. This is followed by an emitter follower stage using the BC547C. This is necessary as the mic and circuit and battery will be some distance from the sound card, the low output impedance of the circuit and screened cable ensuring a clean signal with minimum noise pickup. | | 动态音频前置放大器 | | 动态音频前置放大器
This is a 3 stage discrete amplifier with gain control. Alternative transistors such as BC109C, BC548, BC549, BC549C may be used with little change in performance. The first stage built around Q1 operates in common base configuration. This is unusuable in audio stages, but in this case, it allows Q1 to operate at low noise levels and improves overall signal to noise ratio. Q2 and Q3 form a direct coupled amplifier, similar to my earlier mic preamp.
Input and Output Impedance:
As the signal from a dynamic microphone is low typically much less than 10mV, then there is little to be gained by setting the collector voltage voltage of Q1 to half the supply voltage. In power amplifiers, biasing to half the supply voltage allows for maximum voltage swing, and highest overload margin, but where input levels are low, any value in the linear part of the operating characteristics will suffice. Here Q1 operates with a collector voltage of 2.4V and a low collector current of around 200uA. This low collector current ensures low noise performance and also raises the input impedance of the stage to around 400 ohms. This is a good match for any dynamic microphone having an impedances between 200 and 600 ohms. | | 超声波驱蚊虫器 | | 超声波驱蚊虫器
这是一款极简单的超声波驱蚊、虫、蟑螂电路。
电路由CMOS 4047单稳态触发器构成张弛振荡电路，通过调整4K7，使它的中心频率约在22KHz左右，再由4个晶体管组成的桥式功率输出，去推动3.25 inch Piezo发出超声波信号。
|
| 首页 | 前页 | 后页 | 尾页 | 分页 1/1 [1] |
|
|
|
新闻
