实物图
 LED声压指示器电路原理图  LED声压指示器安装图  LED声压指示器  LED声压指示器面包板制作图
元件清单
R1--10k R2, R3, R5, R7, R8, R10--100k R4--47k R6--1k R9--56k R11--4.7k R12, R14--100 R13--330k R15--220k R16--10/1W R17, R19--390 R18--22k P1--10k audio-taper (log) pot C1, C4, C8--330nF C2--47uF/10V C3, C9--100uF/10V C5--100nF C6--470uF/16V C7--10uF/16V IC1--MC33172P IC2--LM3915P 5V reg--LM2931AZ5.0 LEDs--MV8191 super-red diffused Electret microphone--two-wire type Box--Hammond 1591B Battery--9V Ni-Cad or Ni-MH SW1--SPST switch Adapter jack--switched 原文： This project uses an LM3915 bar-graph IC driving two sets of ten LEDs for a 30dB range. The circuit is unique because it has an additional range of 20dB provided by an automatic gain control to allow it to be very sensitive to low sound levels but it increases its range 20dB for loud sounds. The LEDs are operating at 26mA each with the brightness control at maximum, which is very bright. The circuit has a switch to select the modes of operation: a moving dot of light, or a bar with a changing length. My prototype has a little 9V Ni-Cad rechargeable battery in it to be portable and the battery is trickle-charged when the project is powered by a 9V AC-DC adapter. (责任编辑：admin) |
