LM3916N - two LED's stuck on!

Discussion in 'The Projects Forum' started by phinnay, Sep 29, 2010.

  1. phinnay

    Thread Starter New Member

    Sep 29, 2010
    2
    0
    Hey! new to this forum and getting started on electronics, I downloaded the datasheet for the LM3916N and it seemed really straightforward. I worked out a schematic and it passed the smoke test! Everything is working nice except the first two LED's in the display are on constantly.

    I tried bypassing the peak indicator stage and those lights go out and the graph functions (poorly) with all indicators so I know it's not the chip. One thing I was not clear on in the notes is it says to "dc couple" the input before going into the peak indicator - I looked around and it sounds like they want you to put a cap in series with the input but when I try that, the lights either slowly all turn on as the cap charges and stay lit or nothing happens at all.

    This is the circuit I came up with:

    http://i53.tinypic.com/fcup00.jpg

    Any Ideas?
     
  2. phinnay

    Thread Starter New Member

    Sep 29, 2010
    2
    0
    so ok, I Think it has something to do with the reference voltage in on pins 7 and 8. If I replace the jumper to ground as seen in the linked schematic with a 4.7k resistor, the bottom two LED's start functioning but I have to turn up the stereo attached to it LOUD for it to move into the rest of the LEDs....
     
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