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New guy with a new idea Answered

First off, Hi to everyone!

I made a VU meter using the LM3914N and RGB LEDs.  My "new" idea is to create 2 modes "VU meter" and "lamp".  I can't figure out a way to do this with a single switch.  At first I though it was simple...Oh just put a switch on the 10 LEDs going into the LM3914 and send it to ground.  WRONG!  

Any help would be great!

Thanks!

P.S.  I'm new to all this.

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Natdog
Natdog

8 years ago

OK, now I feel dumb. All you need to do is hook up a SPDT switch to the signal pin (pin #5). Have it switch between your audio signal and the +rail. Works great, in my application. YMMV.

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mpilchfamily
mpilchfamily

8 years ago

So your wanting to have it toggle between using the RGB LEDs as either a UV detector or a light source right?

You will need a switch that will remove the LEDs from the LM3914 and tie them directly to the power source. A 3 position DPDT should do the trick for you. Put the LEDs on the center terminals. Then have the leads going to the IC on one end and the power on the other end. Then you can switch between using the IC and just lighting the LEDs up.

Here is a quick diagram i whipped up for you to make it clear.

swith configuration.jpg
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Natdog
Natdog

Reply 8 years ago

mpilchfamily - Thanks for the response and diagram! This is actually what I was thinking too after I posted this. I'll give it a go.

steveastrouk - Its definitely a 3914 although I had to play around a bit with it an add a LM386 to amplify the audio input from my PC. Works great though.

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steveastrouk
steveastrouk

8 years ago

Just switch an input signal greater than the maximum into the 3914 (do you mean 3915 ? The 3914 is linear, a VU meter is logarithmic )