Electronics help --> LEDS, Variable Resistors, Caps...

[multiplexor]

Hey all

I have a quick question... I have a scanner light (looks like knight rider)... it simply scans from left to right, at any speed i want.

Now I wanted to attach a variable resistor to it so that i could dim the lights... but for some reason it only dims the first LED (in the 8 led scanner... the first first led dims..) (from off to full on), the rest just get a bit dimmer... but that's it...

why is this? should't it dim them fully? is it possible that I have it wired wrong? ie, I have the variable resistor on the wrong wire... the + instead of the -?

The scanner module has one + coming out of it and the other 8 wires are negatives that goto the each individual led's (-) lead.

I attached the variable resistor to the one + wire (since it's easiest to do...)

and i also have a 470ohm resistor before that dimmer resistor...
basically I'm bringing the 12 volts down to around 3 volts for the leds...

after which i want to use the variable resistor to dim the 3 volts from 3 to 0 or 0 to 3... etc...

the + is wired to each leds + lead, in series... next to next to next to next.... etc...

then the other 8 wires, each goto there respective leds lead.

what am i doing wrong????

Also... since leds don't fade... how could I easily get them to fade?
I was thinking attaching a capacitor to each leds lead... this way it would fade out a bit...

help guys!!

Thanks a bunch.

Frank

 

[multiplexor]

as a side note, it's basically exactly like my avatar... lol