WALKMAN_AMPLIFIER

Published:2009/7/2 1:08:00 Author:May | From:SeekIC

Circuit Notes The gain of the low-cost IC is internally fixed so that it is not less than 34 dB（50 times）. A unique input stage allows input signals to be referenced to ground. The output is automatically self centering to one half the supply voltage. The output is also short-circuit proof with internal thermal limiting. With a maximum supply of 15 volts and an 8 ohm load, the output is around 1.5 watts per channel. The input stage is usable with signals from 50 mV to 500 mV rms. If the amplifier is to be used with a source other than a personal stereo, such as a phonograph or an electric guitar, some type of preamplifier is required. A suitable circuit is shown. In that circuit, two 741 op amps have been configured as input amplifiers. Their input stages referenced to a common point-half the supply voltage. That voltage is derived from a voltage divider made up of RI and R2, two 2.2 k resistors. The gain of each of the 741's has been fixed at 21 by the input resistors（R9, R10）. Input capacitors, C1 and C2, are used to filter out any dc component from the input signal.



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