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 一款函数发生器电路 | | | | 一个高精度自动换挡比例运放电路 | | | | 简单的低通滤波器电路 | | 简单的低通滤波器电路 | | Audio Notch Filter | | Audio Notch Filter
At first glance this circuit looks fairly complex, but when broken down,can be divided into high pass and low pass filter sections followed by a summing amplifier with a gain of around 20 times. Supply rail voltage is +/- 9V DC. The controls may also be adjusted for use as a band stop (notch) filter or band pass filter. | | 15W 放大器 | | 15W 放大器
This amplifier uses a dual 20 Volt power supply and delivers 15 watts RMS into an 8 ohm load. Q1 operates in common emitter, the input signal being passed to the bias chain consisting of Q8, Q9, D6, D13 and D14. Q8 and Q9 provide a constant current through the bias chain to minimize distortion, the output stage formed by a discrete darlington pair (Q2,Q4) and (Q7,Q11). The last two transistors are power Transitors, specifically the 2N3055 and MJ2955. The 7.02K resistor, R16 was made using a series combination of a 4.7K, 680 Ohms, and two 820 Ohms. The 1.1K resistor, R3 was made using a 100 Ohms and a 1K resistor. You can use this circuit with any walkman or CD player since it is designed to take a standard 500mv RMS signal. | | 8W 放大器 | | 8W 放大器
Although the TDA2030 can deliver 20 watts of output power, I deliberately reduced the output power to about 8 watts to supply 10 watt speakers. Input sensitivity is 200mV. Higher input levels naturally will give greater output, but no distortion should be heard. The gain is set by the 47k and 1.5k resistors. The TDA2030 IC is affordable and makes a good replacement amplifier for low to medium audio power systems. Incidentally, it is speaker efficiency that determines how "loud" your music is. Speaker efficiency or sound pressure level (SPL) is usually quoted in dB/meter. A speaker with an SPL of 97dB/m will sound louder than a speaker with an SPL of 95dB/m. | | 6通道输入混合器 | | 6通道输入混合器
The mixer circuit below has 3 line inputs and 3 mic inputs. The mic inputs are suitable for low impedance 200-1000R dynamic microphones. An ECM or condenser mic can also be used, but must have bias applied via a series resistor. As with any mixer circuit, a slight loss is always introduced. The final summing amplifier has a gain of 2 or 6dB to overcome this. The Input line level should be around 200mV RMS. The mic inputs are amplified about 100 times or by 40dB, the total gain with the mixer is 46dB. The mic input is designed for microphones with outputs of about 2mV RMS at 1 meter. Most microphones meet this standard. |
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