Ohhh look at the pretty lights...... ( LED implementation info)

[JBVries]

Can you help me? I am trying to figure out how I might achieve this result....

using an LM3916. Heres the data sheet. ... (http://www.google.com/url?sa=t&source=web&cd=2&ved=0CCAQFjAB&url=http%3A%2F%2Fwww.national.com%2Fds%2FLM%2FLM3916.pdf&rct=j&q=lm3916&ei=Jxv_TMTcG5O4sQPapMivCw&usg=AFQjCNHaLUBMOjxlkihMdnWdWSM3ExPJIw&sig2=R1EXZEox1RMcRqcd5vQ_yQ&cad=rja).

I think this is possible. I'm tinkering but my electronics knowledge is still very limited as I started only about 8 months ago. Any advice greatly appreciated. Thanks!!

JB

 

[grantlack]

step 1: void warranty  ;D

 

[JBVries]

This is just a pic I found online.  ???

 

[grantlack]

This is just a pic I found online.  ???

hah fair enough.  well if you're looking at driving led's around a gain pot to mimic the whole 'volume level' deal, it seems to me you'd want to be using the LM3915 (assuming a log pot), no?

 

[abbey road d enfer]

Can you help me? I am trying to figure out how I might achieve this result....

using an LM3916.
I think this is possible. I'm tinkering but my electronics knowledge is still very limited as I started only about 8 months ago. Any advice greatly appreciated. Thanks!!

JB

This would be doable in several manners.
One is to have a special volume pot with an audio log track (two for stereo) AND a lin track driving the input of the LM3916 (with a suitable voltage divider in order to scale the voltage to the 1.2V reference).
Another is to have a single lin pot driving the LM3916 AND a VCA (two for stereo, 4 for quad, umpteen for multispeaker reproduction).
The most technically advanced relies on feeding an A/D converter from the pot (or alternatively using a position encoder) and using the resulting digital code to drive a DCA (two for stereo, ...).

 

[tv]

forum member "livingnote" was developing such mechanisms.

he built several fancy looking devices.

his "page" is here:
http://www.groupdiy.com/index.php?topic=37108.0

 

[JBVries]

Thank you for the responses!

 

[moamps]

...... AND a lin track driving the input of the LM3916 (with a suitable voltage divider in order to scale the voltage to the 1.2V reference)......

Hi,
LM3916 is a log VU driver. LM 3914 or UAA170/180 will be a better choice, IMO.
Regards,
Milan

 

[JBVries]

That's what I am realizing. Is it going to be possible to use the difference in resistance of any pot on any project to add some LEDs to track the movement of the pot? That's what I'm really after.

 

[audiox]

Years ago I designed an instrument which had a transparent dial plate illuminated by four two-colour leds hidden under the potentiometer knob. One section of the linear potentiometer (op-amp buffered) was controlling the current of the red and green led sections.

The result was that dial plate color changed steplessly from green (ccw) throught yellow/orange (mid) to red (cw).

The original purpose was to give a clear visual indication of the control position to the user but it looked nice too.

 

[JBVries]

Hi Audiox,

First off, thanks for the great projects on the boards. Much appreciated.

I was wondering if you would be willing to be kind enough to help me understand how to get the LED results I'm hoping to achieve in a few of my builds.

I am hoping that regardless of the potentiometer figure out hot I can take a couple jumpers off the pot and to a voltage divider (please keep in mind, I am an absolute neophyte) or some other circuit containing a lm3915 to drive the LEDs. Is this thinking at least in the right direction/possible?

I know it's a lot to ask, but would you mind explaining how you did it or showing me a schemo that I can go off of?

I would be very thankful.

JB  

 

[audiox]

Can you help me? I am trying to figure out how I might achieve this result....

Simply take the LM3914 (lin pot) or LM3915 (log pot) input signal from the potentiometer wiper. Schematic: LM3914 datasheet page 2.