Led crescent indicator and driver

[Mgt280y]

Good morning been messing around with my control label designs, I think this may have been looked at before but couldn't find any examples.
I am looking to drill led holes in a crescent same as the sweep of a potentiometer and then to have them turn on as the knob is turned in line with the marker on the knob. Hope I'm making sense so far
I'm guessing if I was to use a duel taper pot one would be for say volume control and other led control
Bit it not sure on is the driver am I right in saying it works by each of the led starting at 1 will require a specific voltatage to turn on the next either in dot or aray form
Any info or experience as always appreciated

[Rixen]

..you would be best to use a bar graph IC, such as LM3914

http://www.ti.com/lit/ds/symlink/lm3914.pdf

[Mgt280y]

Just looked at the data sheet looks Like it might work I'll research a little more 

[Mgt280y]

Can someone help me to understand this one
Looking at the first schematic on the link above I "think" this would do what I need

0v -5v signal source would be one taper of pot?
Where/what is the Vled connected too
The v+ 6.8 - 18v i take is just the circuit supply

How I understand is the led choice is not important

So if I used a 100k pot how would I work out the values to have led 1 always on, with led 2 also on when the pot is in its full anti-clockwise position,
And as the full sweep of the pot is 100k does that mean the increments to light 3 - 10 is every 11.1k
If any understands my rambling could they explain how I work it all out painting by numbers is my way 

Edit just realised led 1 wont be in the crescent as I want an odd number so fully anti is led 2 lit fully clockwise is led 10 lit

[amptramp]

The LM3914 linear LED driver suggested by Rixen is not the only game in town - the LM3915 is a 3 db per step log scale driver and the LM3916 is a VU scale driver.  If you have a level control, get a stereo version of the control and wire the extra pot as the input to the LM3915.  You can set it up so all the lights below the selected one also light up or just the selected one and brightness is controlled by one resistor.

[Mgt280y]

Does anyone have the answers

[ElectricDruid]

Does anyone have the answers

You do! You've got a datasheet which gets you almost all of the way there. You've got some pointers from people above about how to go about it. And you've got the name of a very useful chip that if you google you'll find a million circuits for. The rest you can find out with some experiments on the breadboard. You'll be there in no time.

Tom

[Rixen]

take a look at page 6 of the datasheet, you will see there is a R_hi and REF_out. These are often used connected together, then all the LED's are off when SIG_in is at ground, and all are on when SIG_in is at the same, or higher, than REFout. Connect your pot between REFout and GND, wiper to SIGin, and it will go from zero to ten as the pot is rotated. If you want 1 LED always on, you can either just have a fixed LED, or you can raise the voltage of R_lo just enough to get LED1 to stay on- I would suggest a divider using an 8.2k and 1.5k sourced from REF_out

Do as ElectricDruid suggests, because it will be fun. And post a video :-)

[Mgt280y]

Thank you for your help Im just waiting on a couple of chips and going to have a play, will prob have a question at some point but I'll get as far as I can on the breadboard first