This article refers to the address: http:// An audio preamplifier is required for the preamplifier and balanced analog output of the VCR. The earlier Hi-Fi amplifier included 1 audio input. However, audio preamplifiers are now rare. The CD player has a linear output and does not require linearization. If you want to play a recording or implement LP with a computer audio card, you will find the audio preamplifier useful. The power used is provided by +5V provided by the computer's USB port. No external power supply, dual power or AC power connection is required. The circuit presented here shows a 3.3V powered audio preamplifier. The main advantages of this circuit compared to other op amp solutions are low power, low voltage design and single supply operation. The 100mF, 22mF, and 10mF used in the circuit are tantalum or standard electrolytic capacitors. The 82nF and 22nF capacitors are 2.5% tolerance capacitors. The resistor is a 1% metal film resistor. As can be seen from Table 1, the accuracy is approximately 1 dB. If the high frequency filtering uses a more precise capacitor, the accuracy can be increased. The gain is about 40dB (100) at 1KHz, so the rated 5mV pickup output gives a 500mV output. Increasing the value of the 2nd stage 100KΩ resistor increases the output. ZTTEK Batteries, For 5G backup base station .Customize the lithium ion battery packs according to the application and product requirements of the customers. 48V200Ah Lithium Ion Battery,Lifepo4 Battery 48V 200Ah,Rechargeable Battery 48V 200Ah,48V 200Ah Lifepo4 Battery Pack Jiangsu Zhitai New Energy Technology Co.,Ltd , https://www.ztbatteries.com
The MAX4478 low-noise rail-to-rail four-op amp is the heart of the design. The small MAX8877 linear regulator regulator comes from USB power +5V to +3.3V (Figure 1). In addition, the MAX4478 op amp offers a very high power supply rejection ratio (120dB). This circuit (Figure 2) is used for standard moving magnetic audio pickups. 
Table 1 shows the frequency response of the preamplifier. There is no filter below 20 Hz, so be careful of 50~60Hz noise. This application requires high magnification for low frequencies and is approximately 60 dB (1000) for 20 Hz.
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