LED声压电平指示器的制作(3)
时间:2014-06-17 20:45 来源:未知 作者:admin 点击:次
5) The LM3915 regulates the current for the LEDs so they don’t need current-limiting resistors. In the bar mode with all LEDs lit then the LM3915 gets hot so the 10 ohm/1W resistor R16 shares the heat. Options 1) You could use a switch to change the brightness instead of a pot, or leave it bright. 2) You could use an LM358 dual opamp (I tried it) but its output drops above 4Khz. The MC33172 is flat to 20kHz with this high gain. 3) You could add a 1uF to 2.2uF capacitor across R5 so the indicator responds only to bass or “the beat” of music. Then an LM358 dual opamp is fine.
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