Need help with LM3914 VU Meter

Thread Starter


Joined Jan 25, 2014
Hello all,

I recently picked up a LM3914 to play around with before I started designing a VU meter. I want to simultaneously drive a speaker or headphones, so I need to mitigate the loading effect of putting a relatively small resistance in parallel with the input of the LM3914.

I figured a unity gain buffer would do it, but for some reason, it simply causes all the LEDs to light up. Anyone able to perhaps explain why that's happening, or suggest an alternative? My circuit was working fine until I tried this.

Also, this is hard to describe, but is there a way to "smooth out" the output? I tried a peak detector, which again didn't do anything.

Thank you,
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